MAX2035CCQ+TD [MAXIM]
Ultrasound Variable-Gain Amplifier; 超声可变增益放大器
| 型号： | MAX2035CCQ+TD |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Ultrasound Variable-Gain Amplifier |
| 文件： | 总12页 (文件大小：243K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-0630; Rev 0; 10/06
Ultrasound Variable-Gain Amplifier
MAX2035
General Description
Features
The MAX2035 8-channel variable-gain amplifier (VGA)
is designed for high linearity, high dynamic range, and
low-noise performance targeting ultrasound imaging
and Doppler applications. Each amplifier features dif-
ferential inputs and outputs and a total gain range of
typically 50dB. In addition, the VGAs offer very low out-
put-referred noise performance suitable for interfacing
with 10-bit ADCs.
ꢀ 8-Channel Configuration
ꢀ High Integration for Ultrasound Imaging
Applications
ꢀ Pin Compatible with the MAX2036 Ultrasound
VGA Plus CW Doppler Beamformer
ꢀ Maximum Gain, Gain Range, and Output-Referred
Noise Optimized for Interfacing with 10-Bit ADCs
Maximum Gain of 39.5dB
The MAX2035 VGA is optimized for less than 0.5dB
absolute gain error to ensure minimal channel-to-chan-
nel ultrasound beamforming focus error. The device’s
differential outputs are designed to directly drive ultra-
sound ADCs through an external passive anti-aliasing
filter. A switchable clamp is also provided at each ampli-
fier’s outputs to limit the output signals, thereby prevent-
ing ADC overdrive or saturation.
Total Gain Range of 50dB
√
60nV/ Hz Ultra-Low Output-Referred Noise at
5MHz
Pin-for-Pin 12-Bit Compatibility Supported By
MAX2037/MAX2038
ꢀ
0.5dB Absolute Gain ꢀrror
ꢀ Switchable Output VGA Clamp ꢀliminating ADC
Dynamic performance of the device is optimized to
reduce distortion to support second-harmonic imaging.
The device achieves a second-harmonic distortion
Overdrive
ꢀ Fully Differential VGA Outputs for Direct ADC
specification of -62dBc at V
= 1.5V
and f
=
IN
OUT
P-P
Drive
5MHz, and an ultrasound-specific* two-tone third-order
intermodulation distortion specification of -52dBc at
ꢀ Variable Gain Range Achieves 50dB Dynamic
Range
V
OUT
= 1.5V
and f = 5MHz.
P-P IN
ꢀ -62dBc HD2 at V
= 1.5V and f = 5MHz
P-P IN
OUT
The MAX2035 operates from a +5.0V power supply,
consuming only 127mW/channel. The device is avail-
able in a 100-pin TQFP package with an exposed paddle.
Electrical performance is guaranteed over a 0°C to
+70°C temperature range.
ꢀ Two-Tone Ultrasound-Specific* IMD3 of -52dBc at
= 1.5V and f = 5MHz
V
OUT
P-P
IN
ꢀ 127mW Consumption per Channel
*See the Ultrasound-Specific IMD3 Specification in the
Applications Information section.
Applications
Ultrasound Imaging
Sonar
Ordering Information
Functional Diagram
TꢀMP
RANGꢀ
PKG
CODꢀ
V
CC
V
REF
PART
PIN-PACKAGꢀ
†
100 TQFP-EP
MAX2035
MAX2035CCQ-D
0°C to +70°C
C100E-3
C100E-3
C100E-3
C100E-3
VG_CTL+
VG_CTL-
VG_IN1+
VG_IN1-
-10.5dB TO +39.5dB
(14mm x 14mm)
VG_CLAMP_MODE
VG_OUT1+
†
100 TQFP-EP
MAX2035CCQ-TD 0°C to +70°C
MAX2035CCQ+D 0°C to +70°C
MAX2035CCQ+TD 0°C to +70°C
50Ω
50Ω
VGA
VGA
(14mm x 14mm)
VG_OUT1-
•
•
•
†
100 TQFP-EP
(14mm x 14mm)
•
•
•
•
•
•
•
•
•
•
•
•
50Ω
VG_IN8+
VG_IN8-
VG_OUT8+
VG_OUT8-
†
100 TQFP-EP
(14mm x 14mm)
50Ω
BIAS
CIRCUITRY
†
EP = Exposed paddle.
+Denotes lead-free package.
T = Tape-and-reel package.
D = Dry packing.
PD
GND
EXT_RES
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Ultrasound Variable-Gain Amplifier
ABSOLUTꢀ MAXIMUM RATINGS
CC REF
Any Other Pins to GND...............................-0.3V to (V
V
, V
to GND.................................................-0.3V to +5.5V
Operating Temperature Range...............................0°C to +70°C
Junction Temperature......................................................+150°C
+ 0.3V)
CC
VGA Differential Input Voltage (VGIN_+ - VGIN_-)...........8.0V
Analog Gain-Control Input Differential Voltage
(VG_CTL+ - VG_CTL-)...................................................8.0V
θ
θ
...................................................................................+2°C/W
.................................................................................+22°C/W
P-P
JC
JA
Storage Temperature Range.............................-40°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
P-P
Continuous Power Dissipation (T = +70°C)
A
100-Pin TQFP
(derated 45.5mW/°C above +70°C).........................3636.4mW
MAX2035
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ꢀLꢀCTRICAL CHARACTꢀRISTICS
(Figure 2, V
= V
= 4.75V to 5.25V, GND = 0V, PD = 0, no RF signals applied, capacitance to GND at each of the VGA differen-
REF
CC
tial outputs is 60pF, differential capacitance across the VGA outputs is 10pF, R = 1kΩ, T = 0°C to +70°C. Typical values are at V
L
A
CC
= V
= 5V, T = +25°C, unless otherwise noted.) (Note 1)
A
REF
PARAMꢀTꢀR
Supply Voltage Range
External Reference Voltage
SYMBOL
CONDTIONS
MIN
TYP
MAX
UNITS
V
4.75
5
5.25
V
CC
V
CC
V
(Note 2)
4.75
5
5.25
V
REF
Range
PD = 0
PD =1
204
27
231
33
Refers to V
current plus V
supply
CC
Total Power-Supply Current
mA
current
REF
V
V
Supply Current
Current
I
192
12
216
15
mA
mA
CC
VCC
I
REF
REF
Current Consumption per
Amplifier Channel
Refers to V
supply current
24
27
mA
CC
Minimum gain
Maximum gain
+2
-2
Differential Analog Control
Voltage Range
V
P-P
V
Differential Analog Control
Common-Mode Voltage
V
2.85
2.0
3.0
4.5
3.15
5
CM
Analog Control Input Source/Sink
Current
mA
LOGIC INPUTS
CMOS Input-High Voltage
CMOS Input-Low Voltage
V
V
V
IH
V
0.8
IL
2
_______________________________________________________________________________________
Ultrasound Variable-Gain Amplifier
MAX2035
AC ꢀLꢀCTRICAL CHARACTꢀRISTICS
(Figure 2, V
= 4.75V to 5.25V, V
= 3/5 V , V
= 5.0V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, f = 5MHz, capacitance
CC REF
RF
CM
CC
to GND at each of the VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, R = 1kΩ, T = 0°C
L
A
to +70°C. Typical values are at V
= V
= 5V, T = +25°C, unless otherwise noted.) (Note 1)
REF A
CC
PARAMꢀTꢀR
SYMBOL
CONDITIONS
Differential output
MIN
TYP
MAX
UNITS
capacitance is 10pF,
capacitance to GND
17
V
= 1.5V
,
P-P
OUT
Large-Signal Bandwidth
f
3dB bandwidth,
gain = 20dB
MHz
-3dB
No capacitive load,
R = 1kΩ
L
22
Differential Input Resistance
Input Effective Capacitance
Differential Output Resistance
Maximum Gain
R
C
170
200
15
230
Ω
IN
f
RF
= 10MHz, each input to ground
pF
Ω
IN
R
OUT
100
39.5
-10.5
50
dB
dB
dB
Minimum Gain
Gain Range
T
T
T
= +25°C, -2.0V < VG_CTL < -1.8V
= +25°C, -1.8V < VG_CTL < +1.2V
= +25°C, +1.2V < VG_CTL < +2.0V
0.6
0.5
1.2
1
A
A
A
Absolute Gain Error
dB
VGA Gain Response Time
Input-Referred Noise
50dB gain change to within 1dB final value
µs
VG_CTL set for maximum gain,
no input signal
2
nV/√Hz
No input signal
VG_CTL set for
60
Output-Referred Noise
nV/√Hz
dBc
V
= 1.5V
,
P-P
OUT
+20dB of gain
120
1kHz offset
VG_CLAMP_MODE = 1,
VG_CTL set for +20dB of gain,
-55
-40
-62
-62
-52
f
RF
= 5MHz, V
= 1.5V
OUT P-P
Second Harmonic
HD2
VG_CLAMP_MODE = 1,
VG_CTL set for +20dB of gain,
= 10MHz, V = 1.5V
f
RF
OUT
P-P
VG_CLT set for +20dB of gain,
= 5MHz, f = 5.01MHz,
Third-Order Intermodulation
Distortion
f
IMD3
dB
RF1
RF2
V
= 1.5V
(Note 3)
P-P
OUT
_______________________________________________________________________________________
3
Ultrasound Variable-Gain Amplifier
AC ꢀLꢀCTRICAL CHARACTꢀRISTICS (continued)
(Figure 2, V
= 4.75V to 5.25V, V
= 3/5 V , V
= 5.0V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, f = 5MHz, capacitance
CC REF
RF
CM
CC
to GND at each of the VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, R = 1kΩ, T = 0°C
L
A
to +70°C. Typical values are at V
= V
= 5V, T = +25°C, unless otherwise noted.) (Note 1)
REF A
CC
PARAMꢀTꢀR
SYMBOL
CONDITIONS
differential, f = 10MHz,
MIN
TYP
MAX
UNITS
dB
V
= 1V
P-P
OUT
RF
Channel-to-Channel Crosstalk
-80
VG_CTL set for +20dB of gain
MAX2035
VG_CLAMP_MODE = 0,
VG_CTL set for +20dB of gain,
Maximum Output Voltage at
Clamp ON
V
P-P
differential
2.2
3.4
350mV
differential input
P-P
VG_CLAMP_MODE = 1,
VG_CTL set for +20dB of gain,
Maximum Output Voltage at
Clamp OFF
V
P-P
differential
350mV
differential input
P-P
Note 1: Specifications at T = +25°C and T = +70°C are guaranteed by production test. Specifications at T = 0°C are guaranteed
A
A
A
by design and characterization.
Note 2: Noise performance of the device is dependent on the noise contribution from the supply to V . Use a low-noise supply for
REF
V . V
REF CC
and V
can be connected together to share the same supply voltage if the supply for V
exhibits low noise.
REF
CC
Note 3: See the Ultrasound-Specific IMD3 Specification section.
Typical Operating Characteristics
(Figure 2, V
= V
= 4.75V to 5.25V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, f = 5MHz, capacitance to GND at each of the
REF RF
CC
VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, R = 1kΩ, T = 0°C to +70°C. Typical val-
L
A
ues are at V
= V
= 5V, V
= 3.0V, T = +25°C, unless otherwise noted.)
CC
REF
CM
A
OVERDRIVE PHASE DELAY
vs. FREQUENCY
TWO-TONE ULTRASOUND-SPECIFIC
IMD3 vs. GAIN
POWER-SUPPLY MODULATION RATIO
0
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
-30
V
= 1V DIFFERENTIAL
P-P
V
V
= 35mV DIFFERENTIAL
P-P
V
V
= 1.5V DIFFERENTIAL
P-P
OUT
IN1
IN2
OUT
-10
GAIN = 20dB
= 87.5mV DIFFERENTIAL
= 50mV , f
= 5MHz,
P-P
MOD
P-P CARRIER
-40
-50
-60
-70
-80
-90
GAIN = 20dB
GAIN = 20dB
-20
-30
-40
-50
-60
-70
-80
f = 10MHz
f = 2MHz, 5MHz
-15
-5
5
15
25
35
45
0
2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0
FREQUENCY (MHz)
0
25 50 75 100 125 150 175 200
FREQUENCY (kHz)
GAIN (dB)
4
_______________________________________________________________________________________
Ultrasound Variable-Gain Amplifier
MAX2035
Typical Operating Characteristics (continued)
(Figure 2, V
= V
= 4.75V to 5.25V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, f = 5MHz, capacitance to GND at each of the
REF RF
CC
VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, R = 1kΩ, T = 0°C to +70°C. Typical val-
L
A
ues are at V
= V
= 5V, V
= 3.0V, T = +25°C, unless otherwise noted.)
CM A
CC
REF
SECOND-HARMONIC DISTORTION
vs. GAIN
THIRD-HARMONIC DISTORTION
vs. GAIN
0
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
V
= 1V DIFFERENTIAL
P-P
OUT
V
= 1V DIFFERENTIAL
P-P
OUT
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
f = 12MHz
f = 12MHz
f = 5MHz
f = 5MHz
f = 2MHz
f = 2MHz
-5
-15
5
15
25
35
45
-15
-5
5
15
GAIN (dB)
25
35
45
GAIN (dB)
OVERLOAD RECOVERY TIME
OVERLOAD RECOVERY TIME
MAX2035 toc07
MAX2035 toc06
f = 5MHz
f = 5MHz
DIFFERENTIAL
INPUT
DIFFERENTIAL
INPUT
200mV/div
200mV/div
DIFFERENTIAL
OUTPUT
500mV/div
DIFFERENTIAL
OUTPUT
500mV/div
OUTPUT OVERLOAD TO 100mV
OUTPUT OVERLOAD TO 1V
P-P
P-P
CHANNEL-TO-CHANNEL CROSSTALK
vs. GAIN
CHANNEL-TO-CHANNEL CROSSTALK
vs. FREQUENCY
-30
-40
-50
-60
-60
-65
-70
-75
-80
-85
-90
-95
-100
V
= 1V DIFFERENTIAL
P-P
V
= 1.5V DIFFERENTIAL
P-P
OUT
OUT
GAIN = 20dB, ADJACENT CHANNELS
f = 10MHz, ADJACENT CHANNELS
-70
-80
-90
-100
-110
-15
-5
5
15
25
35
45
1
10
100
FREQUENCY (MHz)
GAIN (dB)
_______________________________________________________________________________________
5
Ultrasound Variable-Gain Amplifier
Typical Operating Characteristics (continued)
(Figure 2, V
= V
= 4.75V to 5.25V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, f = 5MHz, capacitance to GND at each of the
REF RF
CC
VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, R = 1kΩ, T = 0°C to +70°C. Typical val-
L
A
ues are at V
= V
= 5V, V
= 3.0V, T = +25°C, unless otherwise noted.)
CM A
CC
REF
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
OUTPUT-REFERRED NOISE VOLTAGE
vs. GAIN
GAIN vs. DIFFERENTIAL ANALOG
CONTROL VOLTAGE (VG_CTL)
50
45
40
35
30
25
20
15
10
80
70
60
50
40
30
45
35
25
15
5
V
= 1.5V DIFFERENTIAL
P-P
OUT
f = 5MHz
f = 5MHz
VG_CTL = -2V DIFFERENTIAL
P-P
MAX2035
-5
-15
0.1
1
10
100
1000
-15
-5
5
15
25
35
45
-2.5
-1.5
-0.5
0.5
1.5
2.5
FREQUENCY (MHz)
VG_CTL (V DIFFERENTIAL)
P-P
GAIN (dB)
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
40
30
25
20
15
10
5
20
15
10
5
V
= 1.5V DIFFERENTIAL
P-P
V
= 1.5V DIFFERENTIAL
V
= 1.5V DIFFERENTIAL
OUT P-P
OUT
OUT
P-P
35
30
25
20
15
10
5
VG_CTL = -0.8V DIFFERENTIAL
VG_CTL = +0.2V DIFFERENTIAL
VG_CTL = +1.2V DIFFERENTIAL
P-P
P-P
P-P
0
-5
0
-10
-15
-20
-5
-10
0
0.1
1
10
100
1000
0.1
1
10
100
1000
0.1
1
10
100
1000
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (MHz)
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
LARGE-SIGNAL BANDWIDTH
vs. FREQUENCY
HARMONIC DISTORTION
vs. DIFFERENTIAL OUTPUT VOLTAGE
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
10
5
0
-5
V
= 1.5V DIFFERENTIAL
V
= 1V DIFFERENTIAL
OUT P-P
f = 5MHz, GAIN = 20dB
OUT
P-P
VG_CTL = +1.7V DIFFERENTIAL
VG_CTL = +2V DIFFERENTIAL
P-P
P-P
0
-10
-15
-20
-25
-30
-35
-40
-5
THIRD HARMONIC
-10
-15
-20
-25
-30
SECOND HARMONIC
-100
0.1
1
10
100
1000
0.1
1
10
100
1000
0
0.5
1.0
1.5
2.0
2.5
3.0
FREQUENCY (MHz)
FREQUENCY (MHz)
DIFFERENTIAL OUTPUT VOLTAGE (V
)
P-P
6
_______________________________________________________________________________________
Ultrasound Variable-Gain Amplifier
MAX2035
Typical Operating Characteristics (continued)
(Figure 2, V
= V
= 4.75V to 5.25V, GND = 0V, PD = 0, VG_CLAMP_MODE = 1, f = 5MHz, capacitance to GND at each of the
REF RF
CC
VGA differential outputs is 60pF, differential capacitance across the VGA outputs is 10pF, R = 1kΩ, T = 0°C to +70°C. Typical val-
L
A
ues are at V
= V
= 5V, V
= 3.0V, T = +25°C, unless otherwise noted.)
CC
REF
CM
A
HARMONIC DISTORTION
vs. DIFFERENTIAL OUTPUT LOAD RESISTANCE
HARMONIC DISTORTION
vs. DIFFERENTIAL OUTPUT LOAD CAPACITANCE
HARMONIC DISTORTION
vs. FREQUENCY
-40
-40
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
V
= 1V DIFFERENTIAL
P-P
GAIN = 20dB
V
= 1V DIFFERENTIAL
P-P
f = 5MHz, GAIN = 20dB
V
= 1V DIFFERENTIAL
P-P
f = 5MHz, GAIN = 20dB
OUT
OUT
OUT
-45
-50
-55
-60
-65
-70
-75
-80
-85
-90
-95
-100
-45
-50
-55
-60
-65
-70
-75
-80
-85
-90
-95
-100
THIRD HARMONIC
THIRD HARMONIC
THIRD HARMONIC
SECOND HARMONIC
SECOND HARMONIC
SECOND HARMONIC
0
10
20
30
40
50
5
25
45
65
85
105
200
500
800 1100 1400 1700 2000
FREQUENCY (MHz)
DIFFERENTIAL OUTPUT LOAD (pF)
DIFFERENTIAL OUTPUT LOAD (Ω)
TWO-TONE ULTRASOUND-SPECIFIC IMD3
vs. FREQUENCY
GAIN ERROR HISTOGRAM
0
-10
-20
-30
-40
-50
-60
-70
50
45
40
35
30
25
20
15
10
5
V
= 1V DIFFERENTIAL
P-P
OUT
SAMPLE SIZE = 188 UNITS
GAIN = 20dB
f
= 5MHz, GAIN = 20dB
IN_
0
-4.50 -3.00 -1.50 0.75 2.25 3.75
0
5
10
15
20
25
-3.75 -2.25 -0.75 1.50 3.00 4.50
GAIN ERROR (dB)
FREQUENCY (MHz)
OUTPUT COMMON-MODE OFFSET VOLTAGE
vs. GAIN
100
DIFFERENTIAL OUTPUT IMPEDANCE
MAGNITUDE vs. FREQUENCY
200
180
75
50
160
140
25
0
120
100
-25
-50
-75
-100
80
60
0.1
1
10
100
-15
-5
5
15
25
35
45
FREQUENCY (MHz)
GAIN (dB)
_______________________________________________________________________________________
7
Ultrasound Variable-Gain Amplifier
Pin Description
PIN
NAMꢀ
FUNCTION
1, 2, 5, 6, 7, 10,
11, 12, 19, 20,
21, 24, 25, 26,
29, 30, 31, 34,
35, 36, 41, 43,
44, 45, 47, 48,
51, 55, 58, 59,
64, 65, 66, 69,
73, 76, 79, 80,
81, 83, 84, 85,
88–92, 96, 97,
98
MAX2035
GND
Ground
3
4
VGIN3-
VGIN3+
VGIN4-
VGIN4+
EXT_C1
EXT_C2
EXT_C3
VGA Channel 3 Inverting Differential Input
VGA Channel 3 Noninverting Differential Input
8
VGA Channel 4 Inverting Differential Input
9
VGA Channel 4 Noninverting Differential Input
13
14
15
External Compensation. Connect a 4.7µF capacitor to ground.
External Compensation. Connect a 4.7µF capacitor to ground.
External Compensation. Connect a 4.7µF capacitor to ground.
16, 39, 42, 46,
54, 72, 82, 87
5V Power Supply. Bypass each V
pins as possible.
supply to ground with 0.1µF capacitors as close to the
CC
V
CC
17
18
22
23
27
28
32
33
VGIN5-
VGIN5+
VGIN6-
VGIN6+
VGIN7-
VGIN7+
VGIN8-
VGIN8+
VGA Channel 5 Inverting Differential Input
VGA Channel 5 Noninverting Differential Input
VGA Channel 6 Inverting Differential Input
VGA Channel 6 Noninverting Differential Input
VGA Channel 7 Inverting Differential Input
VGA Channel 7 Noninverting Differential Input
VGA Channel 8 Inverting Differential Input
VGA Channel 8 Noninverting Differential Input
5V Reference Supply. Bypass to GND with a 0.1µF capacitor as close to the pins as
possible. Note that noise performance of the device is dependent on the noise contribution
37, 93
V
REF
from the supply to V
. Use a low-noise supply for V
. V
REF CC
and V
can be connected
REF
REF
together to share the same supply voltage if the supply for V
exhibits low noise.
CC
38
40
EXT_RES
PD
External Resistor. Connect a 7.5kΩ resistor to ground.
Power-Down Switch. Drive PD high to set the device in power-down mode. Drive PD low for
normal operation.
49
50
52
53
56
57
60
VGOUT8+
VGOUT8-
VGOUT7+
VGOUT7-
VGOUT6+
VGOUT6-
VGOUT5+
VGA Channel 8 Noninverting Differential Output
VGA Channel 8 Inverting Differential Output
VGA Channel 7 Noninverting Differential Output
VGA Channel 7 Inverting Differential Output
VGA Channel 6 Noninverting Differential Output
VGA Channel 6 Inverting Differential Output
VGA Channel 5 Noninverting Differential Output
8
_______________________________________________________________________________________
Ultrasound Variable-Gain Amplifier
MAX2035
Pin Description (continued)
PIN
61
62
63
67
68
70
71
74
75
77
78
NAMꢀ
FUNCTION
VGA Channel 5 Inverting Differential Output
VGA Analog Gain-Control Inverting Input
VGOUT5-
VG_CTL-
VG_CTL+
VGOUT4+
VGOUT4-
VGOUT3+
VGOUT3-
VGOUT2+
VGOUT2-
VGOUT1+
VGOUT1-
VGA Analog Gain-Control Noninverting Input
VGA Channel 4 Noninverting Differential Output
VGA Channel 4 Inverting Differential Output
VGA Channel 3 Noninverting Differential Output
VGA Channel 3 Inverting Differential Output
VGA Channel 2 Noninverting Differential Output
VGA Channel 2 Inverting Differential Output
VGA Channel 1 Noninverting Differential Output
VGA Channel 1 Inverting Differential Output
VGA Clamp Mode Enable. Drive VG_CLAMP_MODE low to enable VGA clamping. VGA output
86
VG_CLAMP_MODE will be clamped at typically 2.2V differential. Drive VG_CLAMP_MODE high to disable VGA
P-P
clamp mode.
94
95
VGIN1-
VGIN1+
VGIN2-
VGIN2+
EP
VGA Channel 1 Inverting Differential Input
VGA Channel 1 Noninverting Differential Input
99
VGA Channel 2 Inverting Differential Input
100
—
VGA Channel 2 Noninverting Differential Input
Exposed Paddle. Solder the exposed paddle to the ground plane using multiple vias.
VGA Clamp
A clamp is provided to limit the VGA output signals to
avoid overdriving the ADC or to prevent ADC saturation.
Set VG_CLAMP_MODE low to clamp the VGA differential
Detailed Description
The MAX2035’s VGAs are optimized for high linearity,
high dynamic range, and low output-noise perfor-
mance, making this component ideal for ultrasound-
imaging applications. The VGA paths also exhibit a
channel-to-channel crosstalk of -80dB at 10MHz and an
absolute gain error of less than 0.25dB for minimal
channel-to-channel focusing error in an ultrasound sys-
tem. Each VGA path includes circuitry for adjusting
analog gain, an output buffer with differential output
ports (VGOUT_+, VGOUT_-) for driving ADCs, and dif-
ferential input ports (VGIN_+, VGIN_-) that are ideal for
directly interfacing to the MAX2034 quad LNA. See the
Functional Diagram for details.
outputs at 2.2V . Set the VG_CLAMP_MODE high to
P-P
disable the clamp.
Power Down
The device can also be powered down with PD. Set PD
to logic-high for power-down mode. In power-down
mode, the device draws a total supply current of 27mA.
Set PD to a logic-low for normal operation
Overload Recovery
The device is also optimized for quick overload recovery
for operation under the large input signal conditions that
are typically found in ultrasound input buffer imaging
applications. See the Typical Operating Characteristics
for an illustration of the rapid recovery time from a trans-
mit-related overload.
The VGA has an adjustable gain range from -10.5dB to
+39.5dB, achieving a total dynamic range of typically
50dB. The VGA gain can be adjusted with the differen-
tial gain-control input VG_CTL+ and VG_CTL-. Set the
differential gain-control input voltage at -2V for maxi-
mum gain and +2V for minimum gain. The differential
analog control common-mode voltage is typically 3.0V.
_______________________________________________________________________________________
9
Ultrasound Variable-Gain Amplifier
PCB Layout
Applications Information
The pin configuration of the MAX2035 is optimized to
facilitate a very compact physical layout of the device
and its associated discrete components. A typical
application for this device might incorporate several
devices in close proximity to handle multiple channels
of signal processing.
External Compensation
External compensation is required for bypassing inter-
nal biasing circuitry. Connect, as close as possible,
individual 4.7µF capacitors from each pin EXT_C1,
EXT_C2, and EXT_C3 (pin 13, 14, 15) to ground.
The exposed paddle (EP) of the MAX2035’s TQFP-EP
package provides a low thermal-resistance path to the
die. It is important that the PC board (PCB) on which
the MAX2035 is mounted be designed to conduct heat
from the EP. In addition, provide the EP with a low-
inductance path to electrical ground. The EP MUST be
soldered to a ground plane on the PCB, either directly
or through an array of plated via holes.
External Bias Resistor
An external resistor at EXT_RES is required to set the
bias for the internal biasing circuitry. Connect, as close
as possible, a 7.5kΩ resistor from EXT_RES (pin 38) to
ground.
MAX2035
Analog Input and Output Coupling
In typical applications, the MAX2035 is being driven
from a low-noise amplifier (such as the MAX2034) and
is typically driving a discrete differential anti-alias filter
into an ADC (such as the MAX1434 octal ADC). The
differential input impedance of the MAX2035 is typically
200Ω. The differential outputs are capable of driving a
differential load resistance of 1kΩ. The output imped-
ance is 100Ω differential. The differential outputs have
a common-mode bias of approximately 3V. AC-couple
these differential outputs if the next stage has a differ-
ent common-mode input range.
-25dB
ULTRASOUND
IMD3
Ultrasound-Specific IMD3 Specification
Unlike typical communications specs, the two input
tones are not equal in magnitude for the ultrasound-
specific IMD3 two-tone specification. In this measure-
ment, f represents reflections from tissue and f
1
2
represents reflections from blood. The latter reflections
are typically 25dB lower in magnitude, and hence the
measurement is defined with one input tone 25dB lower
f - (f - f )
f
f
f + (f - f )
2 2 1
1
2
1
1
2
than the other. The IMD3 product of interest (f - (f - f ))
1
2
1
presents itself as an undesired Doppler error signal in
ultrasound applications. See Figure 1.
Figure 1. Ultrasound IMD3 Measurement Technique
10 ______________________________________________________________________________________
Ultrasound Variable-Gain Amplifier
MAX2035
Z CONTROL
IN
D2, D1, D0
SINGLE CHANNEL
MAX2034
SINGLE CHANNEL
+V
MAX2035
VG_CTL+
VG_CTL-
18nF
100nF
100nF
100nF
100nF
50Ω
VG_OUT_+
VG_OUT_-
V
IN
VGIN_+
VGIN_-
TO A SINGLE
CHANNEL OF
VGA
50Ω
100nF
MAX1434 ADC
100nF
-V
Figure 2. Typical per-Channel Ultrasound-Imaging Application
Pin Configuration
TOP VIEW
+
GND
GND
1
2
75 VGOUT2-
74
73
72
71
70
69
68
VGOUT2+
GND
VGIN3-
VGIN3+
GND
3
4
V
CC
5
VGOUT3-
VGOUT3+
GND
GND
6
GND
7
8
VGIN4-
VGIN4+
GND
VGOUT4-
9
67 VGOUT4+
66 GND
10
11
12
13
14
15
16
17
18
19
20
21
22
GND
GND
65
GND
64 GND
EXT_C1
EXT_C2
EXT_C3
63 VG_CTL+
62 VG_CTL-
61 VGOUT5-
60 VGOUT5+
MAX2035
V
CC
GND
GND
59
58
VGIN5-
VGIN5+
GND
57 VGOUT6-
56 VGOUT6+
55 GND
GND
GND
VGIN6-
54
V
CC
VGIN6+ 23
53 VGOUT7-
VGOUT7+
GND
24
25
52
51
GND
GND
TQFP
______________________________________________________________________________________ 11
Ultrasound Variable-Gain Amplifier
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
MAX2035
PACKAGE OUTLINE
100L TQFP, 14x14x1.0mm
1
21-0085
B
2
PACKAGE OUTLINE,
100L TQFP, 14x14x1.0mm
2
21-0085
B
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2006 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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