AD830JR [ADI]

High Speed, Video Difference Amplifier; 高速视频差动放大器
AD830JR
型号: AD830JR
厂家: ADI    ADI
描述:

High Speed, Video Difference Amplifier
高速视频差动放大器

放大器
文件: 总16页 (文件大小:336K)
中文:  中文翻译
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High Speed, Video  
Difference Amplifier  
a
AD830  
CO NNECTIO N D IAGRAM  
FEATURES  
Differential Am plification  
8-P in P lastic Mini-D IP (N),  
Wide Com m on-Mode Voltage Range: +12.8 V, –12 V  
Differential Voltage Range: ؎2 V  
High CMRR: 60 dB @ 4 MHz  
Built-in Differential Clipping Level: ؎2.3 V  
Fast Dynam ic Perform ance  
85 MHz Unity Gain Bandw idth  
35 ns Settling Tim e to 0.1%  
360 V/ s Slew Rate  
Sym m etrical Dynam ic Response  
Excellent Video Specifications  
Differential Gain Error: 0.06%  
Differential Phase Error: 0.08؇  
15 MHz (0.1 dB) Bandw idth  
Cerdip (Q) and SO IC (R) P ackages  
AD830  
V
X1  
X2  
Y1  
Y2  
1
2
3
4
8
7
6
5
P
V1  
V1  
OUT  
NC  
A=1  
V
N
NC = NO CONNECT  
Flexible Operation  
High Output Drive of ؎50 m A m in  
Specified w ith Both ؎5 V and ؎15 V Supplies  
Low Distortion: THD = –72 dB @ 4 MHz  
Excellent DC Perform ance: 3 m V m ax Input Offset  
Voltage  
input and produces an output voltage referred to a user-chosen  
level. T he undesired common-mode signal is rejected, even at  
high frequencies. High impedance inputs ease interfacing to fi-  
nite source impedances and thus preserve the excellent  
common-mode rejection. In many respects, it offers significant  
improvements over discrete difference amplifier approaches, in  
particular in high frequency common-mode rejection.  
APPLICATIONS  
Differential Line Receiver  
High Speed Level Shifter  
High Speed In-Am p  
Differential to Single Ended Conversion  
Resistorless Sum m ation and Subtraction  
High Speed A/ D Driver  
T he wide common-mode and differential-voltage range of the  
AD830 make it particularly useful and flexible in level shifting  
applications, but at lower power dissipation than discrete solu-  
tions. Low distortion is preserved over the many possible differ-  
ential and common-mode voltages at the input and output.  
P RO D UCT D ESCRIP TIO N  
Good gain flatness and excellent differential gain of 0.06% and  
phase of 0.08° make the AD830 suitable for many video system  
applications. Furthermore, the AD830 is suited for general pur-  
pose signal processing from dc to 10 MHz.  
T he AD830 is a wideband, differencing amplifier designed for  
use at video frequencies but also useful in many other applica-  
tions. It accurately amplifies a fully differential signal at the  
110  
100  
90  
9
V
= ±5V  
S
6
3
R
= 150Ω  
L
C
= 33pF  
L
0
80  
V
= ±15V  
–3  
S
C
= 4.7pF  
L
70  
60  
50  
40  
30  
–6  
–9  
V
= ±5V  
S
–12  
–15  
–18  
–21  
C
= 15pF  
L
10k  
100k  
1M  
10M  
100M  
1G  
1k  
10k  
100k  
1M  
10M  
FREQUENCY – Hz  
FREQUENCY – Hz  
Com m on-Mode Rejection Ratio vs. Frequency  
Closed-Loop Gain vs. Frequency, Gain = +1  
REV. A  
Inform ation furnished by Analog Devices is believed to be accurate and  
reliable. However, no responsibility is assum ed by Analog Devices for its  
use, nor for any infringem ents of patents or other rights of third parties  
which m ay result from its use. No license is granted by im plication or  
otherwise under any patent or patent rights of Analog Devices.  
One Technology Way, P.O. Box 9106, Norw ood, MA 02062-9106, U.S.A.  
Tel: 617/ 329-4700 Fax: 617/ 326-8703  
AD830–SPECIFICATIONS (V = ؎15 V, R  
LOAD = 150 , CLOAD = 5 pF, T = +25؇C unless otherwise noted)  
S
A
AD 830J/A  
Typ  
AD 830S1  
Typ  
P aram eter  
Conditions  
Min  
Max  
Min  
Max  
Units  
DYNAMIC CHARACT ERIST ICS  
3 dB Small Signal Bandwidth  
0.1 dB Gain Flatness Frequency Gain = 1, VOUT = 100 mV rms  
Differential Gain Error  
Differential Phase Error  
Slew Rate  
Gain = 1, VOUT = 100 mV rms  
75  
11  
85  
15  
75  
11  
85  
15  
MHz  
MHz  
%
Degrees  
V/µs  
V/µs  
MHz  
ns  
ns  
dBc  
dBc  
nV/Hz  
pA/Hz  
0 to +0.7 V, Frequency = 4.5 MHz  
0 to +0.7 V, Frequency = 4.5 MHz  
2 V Step, RL = 500 Ω  
0.06  
0.08  
360  
350  
45  
25  
35  
–82  
–72  
27  
0.09  
0.12  
0.06  
0.08  
360  
350  
45  
25  
35  
–82  
–72  
27  
0.09  
0.12  
4 V Step, RL = 500 Ω  
3 dB Large Signal Bandwidth  
Settling T ime, Gain = 1  
Gain = 1, VOUT = 1 V rms  
VOUT = 2 V Step, to 0.1%  
VOUT = 4 V Step, to 0.1%  
2 V p-p, Frequency = 1 MHz  
2 V p-p, Frequency = 4 MHz  
Frequency = 10 kHz  
38  
38  
Harmonic Distortion  
Input Voltage Noise  
Input Current Noise  
1.4  
1.4  
DC PERFORMANCE  
Offset Voltage  
Gain = 1  
Gain = 1, T MIN–T MAX  
DC  
RL = 1 k, G = ±1  
–1 V X +1 V  
–1.5 V X +1.5 V  
–2 V X +2 V  
VIN = 0 V, +25°C to T MAX  
VIN = 0 V, TMIN  
VIN = 0 V, T MIN–T MAX  
±1.5  
±3  
±5  
±1.5  
±3  
±7  
mV  
mV  
dB  
Open Loop Gain  
Gain Error  
Peak Nonlinearity, RL= 1 k,  
Gain = 1  
64  
69  
64  
69  
±0.1  
0.01  
0.035  
0.15  
5
±0.6  
0.03  
0.07  
0.4  
10  
±0.1  
0.01  
0.035  
0.15  
5
±0.6  
0.03  
0.07  
0.4  
10  
%
% FS  
% FS  
% FS  
µA  
µA  
µA  
Input Bias Current  
Input Offset Current  
7
0.1  
13  
1
8
0.1  
17  
1
INPUT CHARACT ERIST ICS  
Differential Voltage Range  
Differential Clipping Level2  
Common-Mode Voltage Range  
CMRR  
VCM = 0  
Pins 1 and 2 Inputs Only  
VDM = ±1 V  
DC, Pins 1, 2, ±10 V  
DC, Pins 1, 2, ±10 V, T MIN–T MAX 88  
±2.0  
±2.3  
±2.0  
±2.3  
V
V
V
dB  
dB  
dB  
kΩ  
pF  
±2.1  
–12.0  
90  
±2.1  
–12.0  
90  
86  
55  
+12.8  
+12.8  
100  
100  
Frequency = 4 MHz  
55  
60  
370  
2
60  
370  
2
Input Resistance  
Input Capacitance  
OUT PUT CHARACT ERIST ICS  
Output Voltage Swing  
RL 1 kΩ  
±12  
±13  
+13.8, –13.8  
+15.3, –14.7  
±80  
±12  
±13  
+13.8, –13.8  
+15.3, –14.7  
±80  
V
V
mA  
mA  
RL 1 k, ±16.5 VS  
Short to Ground  
RL = 150 Ω  
Short Circuit Current  
Output Current  
±50  
±4  
±50  
±4  
POWER SUPPLIES  
Operating Range  
Quiescent Current  
+ PSRR (to VP)  
– PSRR (to VN)  
PSRR  
±16.5  
17  
±16.5  
17  
V
T
MIN–T MAX  
14.5  
86  
14.5  
86  
mA  
dB  
dB  
dB  
DC, G = 1  
DC, G = 1  
DC, G = 1, ±5 to ±15 VS  
DC, G = 1, ±5 to ±15 VS,  
T MIN–T MAX  
68  
71  
68  
71  
66  
62  
66  
60  
PSRR  
68  
68  
dB  
NOT ES  
1See Standard Military Drawing 5962-9313001MPA for specifications.  
2Clipping level function on X channel only.  
Specifications subject to change without notice.  
–2–  
REV. A  
AD830  
(V = ؎5 V, RLOAD = 150 , CLOAD = 5 pF, T = +25؇C unless otherwise noted)  
S
A
AD 830J/A  
Typ  
AD 830S1  
Typ  
P aram eter  
Conditions  
Min  
Max  
Min  
Max  
Units  
DYNAMIC CHARACT ERIST ICS  
3 dB Small Signal Bandwidth  
0.1 dB Gain Flatness Frequency Gain = 1, VOUT = 100 mV rms  
Gain = 1, VOUT = 100 mV rms  
35  
5
40  
6.5  
35  
5
40  
6.5  
MHz  
MHz  
Differential Gain Error  
Differential Phase Error  
Slew Rate, Gain = 1  
0 to +0.7 V, Frequency = 4.5 MHz,  
G = +2  
0 to +0.7 V, Frequency = 4.5 MHz,  
G = +2  
2 V Step, RL = 500 Ω  
4 V Step, RL = 500 Ω  
Gain = 1, VOUT = 1 V rms  
VOUT = 2 V Step, to 0.1%  
VOUT = 4 V Step, to 0.1%  
2 V p-p, Frequency = 1 MHz  
2 V p-p, Frequency = 4 MHz  
Frequency = 10 kHz  
0.14  
0.18  
0.4  
0.14  
0.18  
0.4  
%
0.32  
210  
240  
36  
35  
48  
–69  
–56  
27  
0.32  
210  
240  
36  
35  
48  
–69  
–56  
27  
Degrees  
V/µs  
V/µs  
MHz  
ns  
ns  
dBc  
dBc  
nV/Hz  
pA/Hz  
3 dB Large Signal Bandwidth  
Settling T ime  
30  
30  
Harmonic Distortion  
Input Voltage Noise  
Input Current Noise  
1.4  
1.4  
DC PERFORMANCE  
Offset Voltage  
Gain = 1  
Gain = 1, T MIN–T MAX  
DC  
±1.5  
±3  
±4  
±1.5  
±3  
±5  
mV  
mV  
dB  
Open Loop Gain  
60  
65  
60  
65  
Unity Gain Accuracy  
Peak Nonlinearity, RL= 1 kΩ  
RL = 1 kΩ  
±0.1  
0.01  
0.045  
0.23  
5
±0.6  
0.03  
0.07  
0.4  
10  
±0.1  
0.01  
0.045  
0.23  
5
±0.6  
0.03  
0.07  
0.4  
10  
%
–1 V X +1 V  
–1.5 V X +1.5 V  
–2 V X +2 V  
VIN = 0 V, +25°C to T MAX  
VIN = 0 V, TMIN  
VIN = 0 V, T MIN–T MAX  
% FS  
% FS  
% FS  
µA  
µA  
µA  
Input Bias Current  
Input Offset Current  
7
0.1  
13  
1
8
0.1  
17  
1
INPUT CHARACT ERIST ICS  
Differential Voltage Range  
Differential Clipping Level2  
Common-Mode Voltage Range  
CMRR  
VCM = 0  
Pins 1 and 2 Inputs Only  
VDM = ±1 V  
DC, Pins 1, 2, +4 V to –2 V  
DC, Pins 1, 2, +4 V to –2 V,  
±2.0  
±2.2  
±2.0  
±2.2  
V
V
V
dB  
±2.0  
–2.0  
90  
±2.0  
–2.0  
90  
+2.9  
+2.9  
100  
100  
T
MIN–T MAX  
88  
55  
86  
55  
dB  
dB  
kΩ  
pF  
Frequency = 4 MHz  
60  
370  
2
60  
370  
2
Input Resistance  
Input Capacitance  
OUT PUT CHARACT ERIST ICS  
Output Voltage Swing  
RL 150 Ω  
RL 150 , ±4 VS  
Short to Ground  
±3.2  
±2.2  
±3.5  
+2.7, –2.4  
–55, +70  
±3.2  
±2.2  
±3.5  
+2.7, –2.4  
–55, +70  
V
V
mA  
mA  
Short Circuit Current  
Output Current  
±40  
±4  
±40  
±4  
POWER SUPPLIES  
Operating Range  
Quiescent Current  
+ PSRR (to VP)  
– PSRR (to VN)  
PSRR (Dual Supply)  
PSRR (Dual Supply)  
±16.5  
16  
±16.5  
16  
V
T
MIN–T MAX  
13.5  
86  
68  
13.5  
86  
68  
mA  
dB  
dB  
dB  
DC, G = 1, Offset  
DC, G = 1, Offset  
DC, G = 1, ±5 to ±15 VS  
DC, G = 1, ±5 to ±15 VS,  
T MIN–T MAX  
66  
62  
71  
66  
60  
71  
68  
68  
dB  
NOT ES  
1See Standard Military Drawing 5962-9313001MPA for specifications.  
2Clipping level function on X channel only.  
Specifications subject to change without notice.  
REV. A  
–3–  
AD830  
ABSO LUTE MAXIMUM RATINGS1  
MAXIMUM P O WER D ISSIP ATIO N  
T he maximum power that can be safely dissipated by the  
AD830 is limited by the associated rise in junction temperature.  
For the plastic packages, the maximum safe junction tempera-  
ture is 145°C. For the cerdip, the maximum junction tempera-  
ture is 175°C. If these maximums are exceeded momentarily,  
proper circuit operation will be restored as soon as the die tem-  
perature is reduced. Leaving the AD830 in the “overheated”  
condition for an extended period can result in permanent dam-  
age to the device. T o ensure proper operation, it is important to  
observe the recommended derating curves.  
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V  
Internal Power Dissipation2 . . . . . . . Observe Derating Curves  
Output Short Circuit Duration . . . . Observe Derating Curves  
Common-Mode Input Voltage . . . . . . . . . . . . . . . . . . . . . . ±VS  
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . ±VS  
Storage T emperature Range (Q) . . . . . . . . . –65°C to +150°C  
Storage T emperature Range (N) . . . . . . . . . –65°C to +125°C  
Storage T emperature Range (R) . . . . . . . . . –65°C to +125°C  
Operating T emperature Range  
AD830J . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C  
AD830A . . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C  
AD830S . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to +125°C  
Lead T emperature Range (Soldering 60 seconds) . . . +300°C  
NOT ES  
While the AD830 output is internally short circuit protected,  
this may not be sufficient to guarantee that the maximum junc-  
tion temperature is not exceeded under all conditions. If the  
output is shorted to a supply rail for an extended period, then  
the amplifier may be permanently destroyed.  
1Stresses above those listed under “Absolute Maximum Ratings” may cause  
permanent damage to the device. T his is a stress rating only and functional  
operation of the device at these or any other conditions above those indicated in the  
operational section of this specification is not implied. Exposure to absolute  
maximum rating conditions for extended periods may affect device reliability.  
28-Pin Plastic Package: θJA = 90°C/Watt  
ESD SUSCEP TIBILITY  
ESD (electrostatic discharge) sensitive device. Electrostatic  
charges as high as 4000 volts, which readily accumulate on the  
human body and on test equipment, can discharge without de-  
tection. Although the AD830 features proprietary ESD protec-  
tion circuitry, permanent damage may still occur on these  
devices if they are subjected to high energy electrostatic dis-  
charges. T herefore, proper ESD precautions are recommended  
to avoid any performance degradation or loss of functionality.  
8-Pin SOIC Package: θJA = 155°C/Watt  
8-Pin Cerdip Package: θJA = 110°C/Watt  
O RD ERING GUID E  
Model  
Tem perature Range  
P ackage D escription  
P ackage O ption  
AD830AN  
AD830JR  
5962-9313001MPA*  
–40°C to +85°C  
0°C to +70°C  
–55°C to +125°C  
8-Pin Plastic Mini-DIP  
8-Pin SOIC  
8-Pin Cerdip  
N-8  
R-8  
Q-8  
*See Standard Military Drawing for specifications.  
2.5  
2.0  
1.5  
1.0  
0.5  
0
3.0  
2.8  
2.4  
2.2  
2.0  
1.8  
1.6  
1.4  
1.2  
1.0  
TJ MAX = 175°C  
T
MAX = 145°C  
J
8-PIN MINI-DIP  
8-PIN CERDIP  
0.8  
0.6  
0.4  
0.2  
8-PIN SOIC  
–50  
–30  
–10  
10  
30  
50  
70  
90  
–60 –40 –20  
0
20  
40  
60  
80  
100 120 140  
AMBIENT TEMPERATURE – °C  
AMBIENT TEMPERATURE – °C  
Maxim um Power Dissipation vs. Tem perature,  
Mini-DlP and SOIC Packages  
Maxim um Power Dissipation vs. Tem perature,  
Cerdip Package  
–4–  
REV. A  
Typical Characteristics–  
AD830  
100  
90  
80  
70  
60  
50  
40  
30  
20  
10  
110  
100  
90  
TO V @ ±15V  
P
TO V @ ±5V  
P
TO V @ ±15V  
N
80  
V
= ±15V  
S
TO V @ ±5V  
70  
N
60  
V
= ±5V  
S
50  
40  
30  
1k  
10k  
100k  
1M  
10M  
1k  
10k  
100k  
1M  
10M  
FREQUENCY – Hz  
FREQUENCY – Hz  
Figure 4. Power Supply Rejection Ratio vs. Frequency  
Figure 1. Com m on-Mode Rejection Ratio vs. Frequency  
3
0
–50  
VOUT = 2V p-p  
RL = 150Ω  
GAIN = +1  
±15V  
–3  
R
C
= 150Ω  
L
±5V SUPPLIES  
2ND HARMONIC  
3RD HARMONIC  
–60  
–70  
–80  
–90  
= 4.7pF  
–6  
–9  
L
±10V  
–12  
–15  
–18  
–21  
–24  
–27  
±15V SUPPLIES  
2ND HARMONIC  
3RD HARMONIC  
±5V  
10k  
100k  
1M  
10M  
100M  
1G  
1k  
10k  
100k  
FREQUENCY – Hz  
1M  
10M  
FREQUENCY – Hz  
Figure 5. Closed-Loop Gain vs. Frequency G = +1  
Figure 2. Harm onic Distortion vs. Frequency  
3
9
8
7
6
5
4
3
±5VS  
2
1
±10VS  
0
–1  
–2  
–3  
–4  
±15VS  
–60 –40 –20  
0
20  
40  
60  
80  
100 120 140  
–60 –40 –20  
0
20  
40  
60  
80  
100 120 140  
JUNCTION TEMPERATURE – °C  
JUNCTION TEMPERATURE – °C  
Figure 3. Input Bias Current vs. Tem perature  
Figure 6. Input Offset Voltage vs. Tem perature  
REV. A  
–5–  
AD830  
0.10  
0.09  
0.08  
0.07  
0.06  
0.05  
0.04  
0.03  
0.02  
0.01  
0.10  
0.09  
0.08  
0.07  
0.06  
0.05  
0.04  
0.03  
0.02  
0.01  
0.20  
0.18  
0.16  
0.14  
0.12  
0.10  
0.08  
0.06  
0.04  
0.02  
0.40  
0.36  
0.32  
0.28  
0.24  
0.20  
0.16  
0.12  
0.08  
0.04  
GAIN = +2  
= 500Ω  
GAIN = +2  
R = 150Ω  
L
R
L
FREQ = 4.5MHz  
FREQ = 4.5MHz  
PHASE  
GAIN  
GAIN  
PHASE  
5
6
7
8
9
10  
11  
12  
13  
14  
15  
5
6
7
8
9
10  
11  
12  
13  
14  
15  
SUPPLY VOLTAGE – ±Volts  
SUPPLY VOLTAGE – ±Volts  
Figure 7. Differential Gain and Phase vs. Supply Voltage,  
Figure 10. Differential Gain and Phase vs. Supply Voltage,  
RL = 500  
RL = 150 Ω  
–40  
–50  
–60  
–40  
–50  
HD2 (±5V)  
4MHz  
–60  
HD3 (±5V)  
HD3 (±5V)  
100kHz  
4MHz  
–70  
–70  
HD2 (±15V)  
4MHz  
HD3 (±15V)  
100kHz  
–80  
–80  
–90  
–90  
HD3 (±15V)  
4MHz  
HD2 (±5V)  
100kHz  
HD2 (±15V)  
100kHz  
–100  
0.25  
–100  
0.25  
0.50  
0.75  
1.00  
1.25  
1.50  
1.75  
2.00  
0.50  
0.75  
1.00  
1.25  
1.50  
1.75  
2.00  
PEAK AMPLITUDE – Volts  
PEAK AMPLITUDE – Volts  
Figure 8. Harm onic Distortion vs. Peak Am plitude,  
Frequency = 100 kHz  
Figure 11. Harm onic Distortion vs. Peak Am plitude,  
Frequency = 4 MHz  
50  
40  
30  
20  
10  
15.00  
14.75  
±16.5V  
14.50  
14.25  
14.00  
13.75  
13.50  
13.25  
13.00  
12.75  
12.50  
12.25  
S
±5V  
S
1k  
10k  
100k  
1M  
10M  
–60 –40 –20  
0
20  
40  
60  
80  
100 120 140  
100  
JUNCTION TEMPERATURE – °C  
FREQUENCY – Hz  
Figure 9. Noise Spectral Density  
Figure 12. Supply Current vs. J unction Tem perature  
–6–  
REV. A  
Typical Characteristics–AD830  
3
0
9
AD830  
V
8
1
V
1
P
G
M
6
2
A=1  
7
6
5
±15V  
OUT  
R
C
= 150Ω  
–3  
3
L
3
4
= 0pF  
L
G
C
M
–6  
0
V
N
–9  
–3  
–6  
–9  
–12  
–15  
–18  
–21  
±5V  
V
= 2V  
1
–12  
–15  
–18  
–21  
–24  
–27  
OUT  
(a)  
RESISTOR LESS GAIN OF 2  
AD830  
8
1
2
V
V
P
N
G
M
A=1  
7
6
5
OUT  
3
4
V
1
G
C
M
100k  
1M  
10M  
100M  
1G  
FREQUENCY – Hz  
V
= V  
OUT  
1
(b)  
Figure 13. Closed-Loop Gain vs. Frequency for the  
Three Com m on Connections of Figure 16  
OP-AMP CONNECTION  
AD830  
V
8
1
2
V
V
1
P
N
G
M
A=1  
7
6
5
OUT  
100mV  
3
4
G
C
VS = ± 5V  
M
100  
90  
V
= V  
OUT  
1
(c)  
GAIN OF 1  
Figure 16. Connection Diagram s  
VS = ± 15V  
10  
1V  
0%  
VS = ± 5V  
100  
90  
20ns  
Figure 14. Sm all Signal Pulse Response,  
RL = 150 , CL = 4.7 pF, G = +1  
VS = ± 15V  
10  
0%  
20ns  
9
V
= ±5V  
S
6
3
R
= 150Ω  
L
Figure 17. Large Signal Pulse Response,  
RL = 150 , CL = 4.7 pF, G = +1  
C
= 33pF  
= 15pF  
L
0
C
L
9
6
–3  
C
= 4.7pF  
V
= +15V  
L
S
–6  
C = 33pF  
L
R
= 150Ω  
L
3
C
= 15pF  
–9  
L
0
–12  
–15  
–18  
–21  
–3  
C = 4.7pF  
L
–6  
–9  
10k  
100k  
1M  
10M  
100M  
1G  
–12  
–15  
–18  
–21  
FREQUENCY – Hz  
Figure 15. Closed-Loop Gain vs. Frequency vs.  
CL, G = +1. VS = ±5 V  
10k  
100k  
1M  
10M  
100M  
1G  
FREQUENCY – Hz  
Figure 18. Closed-Loop Gain vs. Frequency, vs.  
CL, G = +1. VS = ±15 V  
REV. A  
–7–  
AD830  
TRAD ITIO NAL D IFFERENTIAL AMP LIFICATIO N  
In the past, when differential amplification was needed to reject  
common-mode signals superimposed with a desired signal; most  
often the solution used was the classic op amp based difference  
amplifier shown in Figure 19. T he basic function VO = V1–V2 is  
simply achieved, but the overall performance is poor and the cir-  
cuit possesses many serious problems that make it difficult to re-  
alize a robust design with moderate to high levels of  
performance.  
AD 830 FO R D IFFERENTIAL AMP LIFICATIO N  
T he AD830 amplifier was specifically developed to solve the  
listed problems with the discrete difference amplifier approach.  
Its topology, discussed in detail in a later section, by design acts  
as a difference amplifier. T he circuit of Figure 20 shows how  
simply the AD830 is configured to produce the difference of two  
signals V1 and V2, in which the applied differential signal is  
exactly reproduced at the output relative to a separate output  
common. Any common-mode voltage present at the input is  
removed by the AD830.  
R
R
1
2
V
2
V
1
2
VI  
V
R
I
3
V
X
Y
OUT  
V
1
A=1  
V
OUT  
ONLY IF R = R = R = R  
R
1
2
3
4
4
DOES  
V
= V – V  
OUT 1 2  
I
VI  
Figure 19. Op Am p Based Difference Am plifier  
V
= V – V  
1 2  
OUT  
P RO BLEMS WITH TH E O P AMP BASED AP P RO ACH  
• Low Common-Mode Rejection Ratio (CMRR)  
• Low Impedance Inputs  
Figure 20. AD830 as a Difference Am plifier  
CMRR Highly Sensitive to the Value of Source R  
Different Input Impedance for the + and – Input  
• Poor High Frequency CMRR  
• Requires Very Highly Matched Resistors R1–R4 to Achieve  
High CMRR  
Halves the Bandwidth of the Op Amp  
High Power Dissipation in the Resistors for Large Common-  
Mode Voltage  
AD VANTAGEO US P RO P ERTIES O F TH E AD 830  
High Common-Mode Rejection Ratio (CMRR)  
High Impedance Inputs  
• Symmetrical Dynamic Response for +1 and –1 Gain  
• Low Sensitivity to the Value of Source R  
• Equal Input Impedance for the + and – Input  
• Excellent High Frequency CMRR  
No Halving of the Bandwidth  
Constant Power Distortion vs. Common-Mode Voltage  
Highly Matched Resistors Not Needed  
–8–  
REV. A  
AD830  
UND ERSTAND ING TH E AD 830 TO P O LO GY  
V
V
X1  
T he AD830 represents Analog Devices’ first amplifier product  
to embody a powerful alternative amplifier topology. Referred to  
as active feedback, the topology used in the AD830 provides in-  
herent advantages in the handling of differential signals, differ-  
ing system commons, level shifting and low distortion, high  
frequency amplification. In addition, it makes possible the  
implementation of many functions not realizable with single op  
amp circuits or is superior to op amp based equivalent circuits.  
With this in mind, it is important to understand the internal  
structure of the AD830.  
G
M
X2  
I
I
X
A=1  
V
OUT  
Y
C
C
V
V
Y1  
G
M
Y2  
T he topology, reduced to its elemental form, is shown below in  
Figure 21. Nonideal effects such as nonlinearity, bias currents  
and limited full scale are omitted from this model for simplicity,  
but are discussed later. T he key feature of this topology is the  
use of two, identical voltage-to-current converters, GM, that  
make up input and feedback signal interfaces. T hey are labeled  
with inputs VX and VY, respectively. T hese voltage to current  
converters possess fully differential inputs, high linearity, high  
input impedance and wide voltage range operation. T his enables  
the part to handle large amplitude differential signals; they also  
provide high common-mode rejection, low distortion and negli-  
gible loading on the source. T he label, GM, is meant to convey  
that the transconductance is a large signal quantity, unlike in the  
front-end of most op amps. T he two GM stage current outputs  
IX and IY, sum together at a high impedance node which is char-  
acterized by an equivalent resistance and capacitance connected  
to an “ac common.” A unity voltage gain stage follows the high  
impedance node to provide buffering from loads. Relative to  
either input, the open loop gain, AOL, is set by the  
V
– V = V – V  
X2 Y Y1  
2
X1  
FOR V = V  
Y2  
OUT  
1
1 + S(C /G  
V
= (V – V + V  
)
Y1  
OUT  
X1  
X2  
)
M
C
Figure 22. Closed-Loop Connection  
Precise amplification is accomplished through closed-loop op-  
eration of this topology. Voltage feedback is implemented via  
the Y GM stage in which where the output is connected to the  
–Y input for negative feedback as shown in Figure 22. An input  
signal is applied across the X GM stage, either fully differentially  
or single-ended referred to common. It produces a current sig-  
nal which is summed at the high impedance node with the out-  
put current from the Y GM stage. Negative feedback nulls this  
sum to a small error current necessary to develop the output  
voltage at the high impedance node. T he error current is usually  
negligible, so the null condition essentially forces the Y GM  
output stage current to exactly equal the X GM output current.  
Since the two transconductances are identical, the differential  
voltage across the Y inputs equals the negative of the differential  
voltage across the X input; VY = –VX or more precisely  
transconductance, GM, working into the resistance, RP; AOL  
=
GM ϫ RP. T he unity gain frequency ω0 dB for the open loop gain  
is established by the transconductance, GM, working into the  
capacitance, CC; ω0 dB = GM/CC. T he open loop description of  
the AD830 is shown below for completeness.  
V
Y2–VY1 = VX1–VX2. T his simple relation provides the basis to  
easily analyze any function possible to synthesize with the  
AD830, including any feedback situation.  
T he bandwidth of the circuit is defined by the GM and the  
capacitor CC. T he highly linear GM stages give the amplifier a  
single pole response, excluding the output amplifier and loading  
effects. It is important to note that the bandwidth and general dy-  
namic behavior is symmetrical (identical) for the noninverting and  
the inverting connections of the AD830. In addition, the input im-  
pedance and CMRR are the same for either connections. T his is  
very advantageous and unlike in a voltage or current feedback  
amplifier, where there is a distinct difference in performance be-  
tween the inverting and noninverting gain. T he practical impor-  
tance of this cannot be overemphasized and is a key feature  
offered by the AD830 amplifier topology.  
V
X1  
X2  
G
M
V
I
I
X
Y
I
Z
A=1  
V
OUT  
I
I
I
= (V – V ) G  
X1 X2 M  
X
Y
Z
V
V
Y1  
= (V – V ) G  
Y1  
Y2  
M
C
R
G
C
P
M
= I + I  
X
Y
Y2  
G
R
M
P
A
=
OLS  
1 + S (C R )  
C
P
Figure 21. Topology Diagram  
REV. A  
–9–  
AD830  
INTERFACING TH E INP UT  
D iffer ential Voltage Range  
Com m on-Mode Voltage Range  
T he maximum applied differential voltage is limited by the clip-  
ping range of the input stages. T his is nominally set at 2.4 volts  
magnitude and depicted in the crossplot (X-Y) photo of Figure  
25. T he useful linear range of the input stages is set at 2 volts,  
but is actually a function of the distortion required for a particu-  
lar application. T he distortion increases for larger differential  
input voltages. A plot of relative distortion versus input differen-  
tial voltage is shown in Figures 8 and 11 in the T ypical Charac-  
teristics section. T he distortion characteristics could impose a  
secondary limit to the differential input voltage for high accu-  
racy applications.  
T he common-mode range of the AD830 is defined by the am-  
plitude of the differential input signal and the supply voltage.  
T he general definition of common-mode voltage, VCM, is usu-  
ally applied to a symmetrical differential signal centered about a  
particular voltage as illustrated by the diagram in Figure 23.  
T his is the meaning implied here for common-mode voltage.  
T he internal circuitry establishes the maximum allowable volt-  
age on the input or feedback pins for a given supply voltage.  
T his constraint and the differential input voltage sets the  
common-mode voltage limit. Figure 24 shows a curve of the  
common-mode voltage range vs. differential voltage for three  
supply voltage settings.  
1V  
1V  
V
MAX  
100  
90  
V
CM  
V
PEAK  
Figure 23. Com m on-Mode Definition  
10  
0%  
15  
+VCM  
±15V = VS  
12  
–VCM  
Figure 25. Clipping Behavior  
+VCM  
9
15  
±10V = VS  
V
P
6
–VCM  
12  
9
+VCM  
±5V = VS  
3
V
N
–VCM  
0
6
3
0
0.4  
0.8  
1.2  
1.6  
2.0  
DIFFERENTIAL INPUT VOLTAGE – VPEAK  
Figure 24. Input Com m on-Mode Voltage Range vs.  
Differential Input Voltage  
0
0
4
8
12  
16  
20  
SUPPLY VOLTAGE – Volts  
Figure 26. Maxim um Output Swing vs. Supply  
–10–  
REV. A  
AD830  
Choice of P olar ity  
the peak output differential voltage can be easily derived from  
T he sign of the gain is easily selected by choosing the polarity of  
the connections to the + and – inputs of the X GM stage. Swap-  
ping between inverting and noninverting gain is possible simply  
by reversing the input connections. T he response of the ampli-  
fier is identical in either connection, except for the sign change.  
T he bandwidth, high impedance, transient behavior, etc., of the  
AD830, is symmetrical for both polarities of gain. T his is very  
advantageous and unlike an op amp.  
the maximum output swing as VOCM = VMAX–VPEAK.  
O utput Cur r ent  
T he absolute peak output current is set by the short circuit cur-  
rent limiting, typically greater that 60 mA. T he maximum drive  
capability is rated at 50 mA, but without a guarantee of distor-  
tion performance. Best distortion performance is obtained by  
keeping the output current 20 mA. Attempting to drive large  
voltages into low valued resistances (e.g., 10 V into 150 ) will  
cause an apparent lowering of the limit for output signal swing,  
but is just the current limiting behavior.  
Input Im pedance  
T he relatively high input impedance of the AD830, for a differ-  
ential receiver amplifier, permits connections to modest imped-  
ance sources without much loading or loss of common-mode  
rejection. T he nominal input resistance is 300 k. T he real limit  
to the upper value of the source resistance is in its effect on  
common-mode rejection and bandwidth. If the source resistance  
is in only one input, then the low frequency common-mode re-  
jection will be lowered to RIN/RS. T he source resistance/input  
1
D r iving Cap Loads  
T he AD830 is capable of driving modest sized capacitive loads  
while maintaining its rated performance. Several curves of band-  
width versus capacitive load are given in Figures 15 and 18. T he  
AD830 was designed primarily as a low distortion video speed  
amplifier, but with a tradeoff, giving up very large capacitive  
load driving capability. If very large capacitive loads must be  
driven, then the network shown in Figure 27 should be used to  
insure stable operation. If the loss of gain caused by the resistor  
RS in series with the load is objectionable, then the optional  
feedback network shown may be added to restore the lost gain.  
f =  
× RS × CIN  
capacitance pole  
limits the bandwidth.  
2π  
Furthermore, the high frequency common-mode rejection will  
be additionally lowered by the difference in the frequency re-  
sponse caused by the RS ϫ CIN pole. T herefore, to maintain  
good low and high frequency common-mode rejection, it is rec-  
ommended that the source resistances of the + and – inputs be  
matched and of modest value (10 k).  
+V  
S
8
7
6
5
1
AD830  
+
V
0.1µF  
CM  
INPUT  
SIGNAL  
H andling Bias Cur r ents  
G
R
S
M
36.5Ω  
T he bias currents are typically 4 µA flowing into each pin of the  
GM stages of the AD830. Since all applications possess some fi-  
nite source resistance, the bias current through this resistor will  
create a voltage drop (IBIAS ϫ RS). T he relatively high input im-  
pedance of the AD830 permits modest values of RS, typically  
10 k. If the source resistance is in only one terminal, then an  
objectional offset voltage may result (e.g., 4 µA ϫ 5 k=  
20 mV). Placement of an equal value resistor in series with the  
other input will cancel the offset to first order. However, due to  
mismatches in the resistances, a residual offset will remain and  
likely be greater than bias current (offset current) mismatches.  
V
OUT  
2
3
4
Z
CM  
R
1
C
1
A=1  
C
1kΩ  
100pF  
G
M
* OPTIONAL  
FEEDBACK  
NETWORK  
0.1µF  
–V  
R
S
S
Applying Feedback  
R
1
T he AD830 is intended for use with gain from 1 to 100. Gains  
greater than one are simply set by a pair of resistors connected  
as shown in the difference amplifier (Figure 35) with gain >1.  
T he value of the bottom resistor R2, should be kept less than  
1 kto insure that the pole formed by CIN and the parallel con-  
nection of R1 and R2 is sufficiently high in frequency so that it  
does not introduce excessive phase shift around the loop and de-  
stabilizes the amplifier. A compensating resistor, equal to the  
parallel combination of R1 and R2, should be placed in series  
with the other Y GM stage input to preserve the high frequency  
common-mode rejection and to lower the offset voltage induced  
by the input bias current.  
Figure 27. Circuit for Driving Large Capacitive Loads  
3
±15V  
0
–3  
±5V  
–6  
–9  
–12  
–15  
–18  
–21  
–24  
–27  
O utput Com m on Mode  
T he output swing of the AD830 is defined by the differential in-  
put voltage, the gain and the output common. Depending on  
the anticipated signal span, the output common (or ground)  
may be set anywhere between the allowable peak output voltage  
in a manner similar to that described for input voltage common  
mode. A plot of the peak output voltage versus supply is shown  
in Figure 26. A prediction of the common-mode range versus  
10k  
100k  
1M  
10M  
100M  
FREQUENCY – Hz  
Figure 28. Closed-Loop Response vs. Frequency with  
100 pF Load and Series Resistor Com pensation  
REV. A  
–11–  
AD830  
V
SUP P LIES, BYP ASSING AND GRO UND ING (FIGURE 29)  
T he AD830 is capable of operating over a wide range of supply  
voltages, both single and dual supplies. T he coupling may be dc  
or ac provided the input and output voltages stay within the  
specified common-mode voltage limits. For dual supplies, the  
device works from ±4 V to ±16.5 V. Single supply operation is  
possible over +8 V to +33 V. It is also possible to operate the  
part with split supply voltages (e.g., +24 V, –5 V) for special  
applications such as level shifting. T he primary constraint is that  
the total potential between the two supplies does not exceed  
33 V.  
P
+
8
7
6
5
1
2
3
4
AD830  
V
IN  
G
G
M
V
OUT  
+
A=1  
V
ICM  
M
C
Inclusion of power supply bypassing capacitors is necessary to  
achieve stable behavior and the specified performance. It is es-  
pecially important when driving low resistance loads. At a mini-  
mum, connect a 0.1 µF ceramic capacitor at the supply lead of  
the AD830 package. In addition, for the best by passing, we rec-  
ommend connecting a 0.01 µF ceramic capacitor and 4.7 µF  
tantalum capacitor to the supply lead going to the AD830.  
+
V
OCM  
V
= (V – V  
) + V  
OCM  
OUT  
IN  
ICM  
Figure 30. General Single Supply Connection  
V
P
V
30  
28  
P
AND  
AND  
V
N
V
N
0.01µF  
0.1µF  
24  
20  
VP = +30V  
4.7µF  
LOAD  
GND  
LEAD  
LOAD  
GND  
LEAD  
VP = +15V  
VP = +10V  
16  
12  
8
(a)  
(b)  
Figure 29. Supply Decoupling Options  
TO GND  
0.4  
4
T he AD830 is designed by its functionality to be capable of  
rejecting noise and dissimilar potentials in the ground lines.  
T herefore, proper care is necessary to realize the benefits of the  
differential amplification of the part. Separation of the input and  
output grounds is crucial in rejection of the common mode  
noise at the inputs and eliminating any ground drops on the in-  
put signal line. For example, connecting the ground of a coaxial  
cable to the AD830 output common (board ground) could de-  
grade the CMR and also introduce power-down loading on  
cable grounds. However, it is also necessary as in any electronic  
system, to provide a return path for bias currents back to their  
original power supply. T his is accomplished by providing a con-  
nection between the differing grounds through a modest imped-  
ance labeled ZCM (e.g., 100 ).  
0
0
0.8  
1.2  
1.6  
2.0  
DIFFERENTIAL INPUT VOLTAGE – VPEAK  
Figure 31. Input Com m on-Mode Range for Single Supply  
28  
TO VP  
24  
20  
16  
Single Supply O per ation  
12  
8
T he AD830 is capable of operating in single power supply appli-  
cations down to a voltage of +8 V, with the generalized connec-  
tion shown in Figure 30. T here is a constraint on the  
common-mode voltage at the input and output which estab-  
lishes the range for these voltages. Direct coupling may be used  
for input and output voltages which lie in these ranges. Any gain  
network applied needs to be referred to the output common  
connection or have an appropriate offset voltage. In situations  
where the signal lies at a common voltage outside the common  
mode range of the AD830 direct coupling will not work, so ac  
coupling should be used. A tested application included later in  
this data sheet (Figure 42), shows how to easily accomplish cou-  
pling to the AD830. For single supply operation where direct  
coupling is desired the input and output common-mode curves  
(Figures 31 and 32) should be used.  
TO GND  
4
0
10  
14  
18  
22  
26  
30  
SUPPLY VOLTAGE – Volts  
Figure 32. Output Swing Lim it for Single Supply  
–12–  
REV. A  
AD830  
D iffer ential Line Receiver  
D iffer ence Am plifier with Gain > 1  
T he AD830 was specifically designed to perform as a differen-  
tial line receiver. T he circuit in Figure 33 shows how simple it is  
to configure the AD830 for this function. T he signal from sys-  
tem “A” is received differentially relative to A’s common, and  
that voltage is exactly reproduced relative to the common in sys-  
tem B. T he common-mode rejection versus frequency, shown in  
Figure 1, is excellent, typically 100 dB at low frequencies. T he  
high input impedance permits the AD830 to operate as a bridg-  
ing amplifier across low impedance terminations with negligible  
loading. T he differential gain and phase specifications are very  
good as shown in Figure 7 for 500 and Figure 10 for 150 .  
T he input and output common should be separated to achieve  
the full CMR performance of the AD830 as a differential ampli-  
fier. However, a common return path is necessary between sys-  
tems A and B.  
T he AD830 can provide instrumentation amplifier style differ-  
ential amplification at gains greater than 1. T he input signal is  
connected differentially and the gain is set via feedback resistors  
as shown in Figure 35. T he gain, G = (R2 + R1)/R2. T he AD830  
can provide either inverting or noninverting differential amplifi-  
cation. T he polarity of the gain is established by the polarity of  
the connection at the input. Feedback resistors R2 should gener-  
ally be R2 1 kto maintain closed-loop stability and also keep  
bias current induced offsets low. Highest CMRR and lowest dc  
offsets are preserved by including a compensating resistor in  
series with Pin 3. T he gain may be as high as 100.  
V
P
0.1µF  
AD830  
8
V
1
2
3
4
1
V
G
G
CM  
M
V
P
INPUT  
SIGNAL  
V
OUT  
0.1µF  
7
6
5
V
2
AD830  
V
8
1
A=1  
1
V
G
G
CM  
Z
M
CM  
INPUT  
SIGNAL  
R
R
2
1
V
OUT  
C
2
3
4
7
6
5
V
2
M
A=1  
0.1µF  
COMMON IN  
SYSTEM A  
Z
CM  
C
R1  
M
V
N
0.1µF  
R2  
V
N
V
= (V – V ) (1+R /R )  
1 2 1 2  
OUT  
V
= V – V  
1
2
COMMON IN  
SYSTEM  
OUT  
B
Figure 35. Gain of G Differential Am plifier, G > 1  
O ffsetting the O utput with Gain  
Figure 33. Differential Line Receiver  
Wide Range Level Shifter  
Some applications, such as A/D drivers, require that the signal  
be amplified and also offset, typically to accommodate the input  
range of the device. T he AD830 can offset the output signal  
very simply through Pin 3 even with gain > 1. T he voltage ap-  
plied to Pin 3 must be attenuated by an appropriate factor so  
that V3 ϫ G = desired offset. In Figure 36, a resistive divider  
from a voltage reference is used to produce the attenuated offset  
voltage.  
T he wide common-mode range and accuracy of the AD830 al-  
lows easy level shifting of differential signals referred to an input  
common-mode voltage to any new voltage defined at the out-  
put. T he inputs may be referenced to levels as high as 10 V at  
the inputs with a ±2 V swing about 10 V. In the circuit of Fig-  
ure 34, the output voltage, VOUT , is defined by the simple equa-  
tion shown below. T he excellent linearity and low distortion are  
preserved over the full input and output common-mode range.  
T he voltage sources need not be of low impedance, since the  
high input resistance and modest input bias current of the  
AD830 V-to-I converters permit the use of resistive voltage di-  
viders as reference voltages.  
V
P
0.1µF  
AD830  
V
1
8
7
1
V
G
CM  
M
INPUT  
SIGNAL  
V
OUT  
2
3
4
V
2
A=1  
V
P
Z
CM  
R
R
2
1
0.1µF  
6
5
AD830  
C
G
V
1
8
7
6
5
1
M
G
G
M
INPUT  
SIGNAL  
0.1µF  
V
OUT  
2
3
4
V
2
V
REF  
R
A=1  
1
INPUT  
COMMON  
V
N
R
C
2
M
R
3
0.1µF  
V
3
V
= (V – V ) (1+R /R )  
1 2 1 2  
OUT  
R
4
V
N
V
3
V
= V – V + V  
1 2 3  
OUT  
OUTPUT  
Figure 36. Offsetting the Output with Differential Gain > 1  
COMMON  
Figure 34. Differential Am plification with Level Shifting  
REV. A  
–13–  
AD830  
Loop Thr ough or Line Br idging Am plifier (Figur e 37)  
T he AD830 is ideally suited for use as a video line bridging am-  
plifier. T he video signal is tapped from the conductor of the  
cable relative to its shield. T he high input impedance of the  
AD830 provides negligible loading on the cable. More signifi-  
cantly, the benign loading is maintained while the AD830 is  
powered-down. Coupled with its good video load driving per-  
formance, the AD830 is well suited to video cable monitoring  
applications.  
inputs VX1 and VY1 together and applying the input, VIN, to this  
wired connection. T he output is exactly twice the applied volt-  
age, VIN; VOUT = 2 ϫ VIN. Figure 39 below shows the connec-  
tions for this highly useful application. T he most notable  
characteristic of this alternative gain of two is that there is no  
loss of bandwidth as in a voltage feedback op amp based gain of  
+2 where the bandwidth is halved, therefore, the gain band-  
width is doubled. Also, this circuit is accurate without the need  
for any precise valued resistors, as in the op amp equivalents,  
and it possess excellent differential gain and phase performance  
as shown in Figures 40 and 41.  
V
P
V
P
0.1µF  
AD830  
1
8
7
6
5
0.1µF  
AD830  
G
G
M
1
8
7
6
5
G
G
V
M
75  
OUT  
V
R
2
3
4
IN  
G
V
75Ω  
OUT  
A=1  
2
3
4
A=1  
249Ω  
75Ω  
M
75Ω  
C
0.1µF  
M
C
0.1µF  
499Ω  
499Ω  
V
N
V
N
OPTIONAL C  
C
Figure 39. Full Bandwidth Line Driver (G = +2)  
.10  
.20  
Figure 37. Cable Tap Am plifier  
Resistor less Sum m ing  
GAIN = +2  
= 150Ω  
.09  
.08  
.07  
.06  
.05  
.04  
.03  
.02  
.01  
.18  
.16  
.14  
.12  
.10  
.08  
.06  
.04  
.02  
R
L
FREQ = 3.58MHz  
0 TO 0.7V  
Direct, two input, resistorless summing is easily realized from  
the general unity gain mode. By grounding VX2 and applying the  
two inputs to VX1 and VY1, the output is the exact sum of the  
applied voltages V1 and V3, relative to common; VOUT = V1 +  
V3. A diagram of this simple, but potent application is shown  
below in Figure 38. T he AD830 summing circuit possesses sev-  
eral virtues not present in the classic op amp based summing  
circuits. It has high impedance inputs, no resistors, very precise  
summing, high reverse isolation and noninverting gain. Achiev-  
ing this function and performance with op amps requires signifi-  
cantly more components.  
PHASE  
GAIN  
5
6
7
8
9
10  
11  
12  
13  
14  
15  
SUPPLY VOLTAGE – ±Volts  
V
P
AD830  
Figure 40. Differential Gain and Phase for the Circuit of  
Figure 39  
1
8
G
G
M
V
1
OUT  
0.2  
0.1  
2
3
4
7
6
5
A=1  
V
= ±15V  
S
0
–0.1  
–0.2  
–0.3  
–0.4  
–0.5  
–0.6  
–0.7  
–0.8  
M
C
V
3
R
= 150Ω  
L
GAIN = +2  
V
N
V
= V + V  
1 3  
OUT  
V
= ±10V  
S
Figure 38. Resistorless Sum m ing Am plifier  
2
؋
 Gain Bandwidth Line D r iver  
A gain of two, without the use of resistors, is possible with the  
AD830. T his is accomplished by grounding VX2, tying the two  
V
= ±5V  
S
10k  
100k  
1M  
10M  
100M  
FREQUENCY – Hz  
Figure 41. 0.1 dB Gain Flatness for the Circuit of Figure 39  
–14–  
REV. A  
AD830  
AC CO UP LED LINE RECEIVER  
becomes troublesome. For dual supply operation, the 10 kΩ  
resistors may go directly to ground. T he output common is con-  
veniently set by a Zener diode for a low impedance reference to  
preserve the high frequency CMR. However, a simple resistive  
divider will work fine and good high frequency CMR can be  
maintained by placing a compensating resistor in series with the  
+Y input. T he excellent CMRR response of the circuit is shown  
in Figure 43. A plot of the 0.1 dB flatness from 10 Hz is also  
shown. With the use of 10 µF capacitors, the CMR is >90 dB  
down to a few tens of hertz. T his level of performance is almost  
impossible to achieve with discrete solutions.  
T he AD830 is configurable as an ac coupled differential ampli-  
fier on a single or bipolar supply voltages. All that is needed is  
inclusion of a few noncritical passive components as illustrated  
below in Figure 42. A simple resistive network at the X GM  
input establishes a common-mode bias. Here, the common  
mode is centered at 6 volts, but in principle can be any voltage  
within the common-mode limits of the AD830. T he 10 kre-  
sistors to each input bias the X GM stage with sufficiently high  
impedance to keep the input coupling corner frequency low, but  
not too large so that residual bias current induced offset voltage  
+12V  
INPUT  
10µF  
0.1µF  
AD830  
SIGNAL  
8
1
75  
COAX  
G
M
R
T
V
CABLE  
75Ω  
OUT  
2
3
4
7
6
5
Z
CM  
A=1  
10µF  
1000µF  
10kΩ  
10kΩ  
2k*  
75Ω  
+V  
S
G
M
C
10kΩ  
+12V  
4.7kΩ  
10kΩ  
*OPTIONAL TUNING FOR  
IMPROVING VERY LOW  
FREQUENCY CMR.  
6.8V  
1N4736  
Figure 42. AC Coupled Line Receiver  
120  
100  
80  
1
0
WITH CIRCUIT TRIMMED  
USING EXTERNAL 2k  
POTENTIOMETER  
–0.1  
–0.2  
–0.3  
–0.4  
–0.5  
WITHOUT EXTERNAL  
2kPOTENTIOMETER  
60  
–0.6  
–0.7  
–0.8  
40  
–0.9  
10  
20  
100  
1k  
10k  
100k  
1M  
10M  
10  
100  
1k  
10k  
100k  
1M  
10M  
100M  
FREQUENCY – Hz  
FREQUENCY – Hz  
Figure 44. Am plitude Response vs. Frequency for Line  
Receiver  
Figure 43. Com m on-Mode Rejection vs. Frequency for  
Line Receiver  
REV. A  
–15–  
AD830  
O UTLINE D IMENSIO NS  
D imensions shown in inches and (mm).  
Cerdip (Q) P ackage  
0.005 (0.13) MIN  
0.055 (1.4) MAX  
8
5
0.310 (7.87)  
PIN 1  
0.220 (5.59)  
1
4
0.320 (8.13)  
0.290 (7.37)  
0.405 (10.29) MAX  
0.060 (1.52)  
0.015 (0.38)  
0.200  
(5.08)  
MAX  
0.150  
(3.81)  
MIN  
0.015 (0.38)  
0.008 (0.20)  
0.200 (5.08)  
0.125 (3.18)  
15  
°
0°  
0.023 (0.58) 0.100  
0.070 (1.78)  
0.030 (0.76)  
SEATING  
PLANE  
(2.54)  
BSC  
0.014 (0.36)  
P lastic Mini-D IP (N) P ackage  
8
5
0.280 (7.11)  
0.240 (6.10)  
PIN 1  
1
4
0.325 (8.25)  
0.300 (7.62)  
0.430 (10.92)  
0.348 (8.84)  
0.060 (1.52)  
0.015 (0.38)  
0.195 (4.95)  
0.115 (2.93)  
0.210  
(5.33)  
MAX  
0.130  
(3.30)  
MIN  
0.015 (0.381)  
0.008 (0.204)  
0.160 (4.06)  
0.115 (2.93)  
SEATING  
PLANE  
0.100  
(2.54)  
0.022 (0.558)  
0.014 (0.356)  
0.070 (1.77)  
0.045 (1.15)  
BSC  
8-P in SO IC (R) P ackage  
0.198 (5.00)  
0.188 (4.75)  
5
8
0.158 (4.00)  
0.150 (3.80)  
0.244 (6.200)  
0.228 (5.80)  
1
4
0.050  
(1.27)  
TYP  
0.018 (0.46)  
0.014 (0.36)  
0.205 (5.20)  
0.181 (4.60)  
0.102 (2.59)  
0.094 (2.39)  
0.010 (0.25)  
0.004 (0.10)  
0.045 (1.15)  
0.020 (0.50)  
0.015 (0.38)  
0.007 (0.18)  
All brand or product names mentioned are trademarks or registered trademarks of their respective holders.  
–16–  
REV. A  

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