DEM-OPA660-5G [ETC]
DEM-OPA660-5G - DISCONTINUED PRODUCT. No longer recommended for new design. ; DEM - OPA660-5G - 停产的产品。不再建议用于新设计。\n
| 型号： | DEM-OPA660-5G |
| 厂家： | 
ETC |
| 描述： | DEM-OPA660-5G - DISCONTINUED PRODUCT. No longer recommended for new design.
|
| 文件： | 总6页 (文件大小：327K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
®
DEM-OPA660-5G
EVALUATION FIXTURE
APPLICATIONS
FEATURES
● COMPONENTS INCOME CONTROL
● PERFORMANCE CHECKS
● CIRCUIT DESIGNS
● EASY AND FAST PERFORMANCE
TESTING
● SHOWS OPTIMIZED BOARD LAYOUT
● REPLACES SELF-MADE BOARDS
DESCRIPTION
The unassembled demo board DEM-OPA660-5G con-
tains three different configurations of the OPA660
building blocks OTA and buffer stage: the Diamond
Transistor and Buffer (DEM-OPA660-1GC), the Cur-
rent-Feedback Amplifier (DEM-OPA660-2GC), and
the Direct-Feedback Amplifier (DEM-OPA660-3GC).
It is designed for engineers who want to test the
various possibilities of the OPA660AP for themselves.
with the OPA660, please refer to the application notes
AN-179 “Video Operational Amplifier,” AN-180
“Ultra High-Speed ICs,” and AN-181 “Diamond Tran-
sistor OPA660,” as well as the OPA660 data sheet.
The DEM-OPA660-5G offers the three configura-
tions, which are available individually as assembled
and tested boards, for DIL packaging (OPA660AP).
An unassembled version of the configurations is
available for the SO package (OPA660AU) under the
part number DEM-OPA660-4G.
The board can be easily broken into three parts to
design custom circuits as required by the particular
application. For more information about applications
International Airport Industrial Park
•
Mailing Address: PO Box 11400
Cable: BBRCORP
•
Tucson, AZ 85734
•
Street Address: 6730 S. Tucson Blvd.
• Tucson, AZ 85706
Tel: (602) 746-1111 Twx: 910-952-1111
•
•
•
Telex: 066-6491
•
FAX: (602) 889-1510
•
Immediate Product Info: (800) 548-6132
© 1992 Burr-Brown Corporation
LI-417
Printed in U.S.A. December, 1992
TEST FIXTURE:
RECOMMENDED COMPONENT VALUES
DIAMOND TRANSISTOR AND BUFFER
GAIN
R1
R4
R6
R7
IQ
RQC
Description
1
2
100Ω
100Ω
100Ω
200Ω
51Ω
25Ω
75Ω
50Ω
50Ω
50Ω
20mA
20mA
20mA
250Ω
250Ω
250Ω
This printed circuit board allows easy and fast performance
testing of the OPA660AP building blocks OTA and buffer
stage. The voltage-controlled current source or Operational
Transconductance Amplifier (OTA) can be viewed as an
“ideal” transistor. Like a transistor, it has three terminals: a
high-impedance input (base), a low-impedance input/output
(emitter), and the complementary current source or sink
(collector). The OTA, however, is self-biased and bipolar.
The transconductance of the OTA and the buffer amplifier
can be adjusted by the external resistor RQC, allowing band-
width, quiescent current, and gain trade-offs to be opti-
mized.
10
51Ω
475Ω
The low-frequency gain of a common emitter amplifier is
determined by the following equation:
RL
RL
R4
G =
~
1
R4 +
gm
where RL = R2 + R3
The voltage buffer is an open-loop buffer with gain slightly
less than unity, which is ideal for interstage buffering.
Figure 1 shows the schematic diagram of the board layout
and the recommended power supply bypassing. Figure 3
illustrates the OTA transfer characteristics vs input voltage
and IQ, and the performance curve Total Quiescent Current
vs RQC shown in Figure 2 defines the resistor value for a
certain IQ.
TEST FIXTURE:
CURRENT-FEEDBACK AMPLIFIER
Description
When the OTA and buffer section are combined, these sec-
tions of the OPA660 can be interconnected in a current-
feedback amplifier configuration. Current-feedback amplifi-
R5
R6
5
6
BUF In
1
BUF Out
R7
+5V
–5V
R2
1
OTA Out
RQC
470p
10n
470p
10n
8
R1
R3
3
OTA In
2
2.2µ
2.2µ
C1
C2
R4
IN4007
7
4
FIGURE 1. Block Diagram of the Test Fixture’s Diamond Transistor and Buffer.
10
5
100
30
IQ = 5mA
0
10
IQ = 10mA
IQ = 20mA
–5
3.0
1.0
–10
–60
–40
–20
0
20
40
60
100
300
1.0k
3.0k
10k
OTA Input Voltage (mV)
RQC — Resistor Value (Ω)
FIGURE 2. Total Quiescent Current vs RQC of the Diamond
Transistor and Buffer.
FIGURE 3. OTA Transfer Characteristics.
®
2
DEM-OPA660-5G
FIGURE 4. Silk Screen and Board Layouts of the Diamond Transistor and Buffer.
ers have nearly constant bandwidth for varying closed-loop
gains. The reason is that the user can adjust the open-loopgain
of the current-feedback amplifier by changing the feedback
network,withoutaffectingtheopen-looppole.Figure5shows
the block diagram of the Current-Feedback Amplifier test
fixture.
The size of R3 is equal to the characteristic impedance of the
transmission line minus the output resistance of the ampli-
fier. Figure 6 illustrates the silk screen and double-sided
layout.
TEST FIXTURE:
DIRECT-FEEDBACK AMPLIFIER
The low-frequency gain of a noninverting current-feedback
amplifier is determined by the following equation:
Description
The demo board layout allows easy and fast performance
testing of the OPA660AP in the so-called Direct-Feedback
Amplifier configuration. We named this structure Direct-
Feedback Amplifier due to its short feedback loop across the
complementary current mirror. The currents at the collector
and emitter flow in the same direction. The output current of
the OTA is noninverting. The additional current flowing
from the collector across R3 and through R5 causes a voltage
drop and counteracts the base-emitter voltage. The reduced
voltage difference, however, causes reduced collector cur-
rent flow. It functions like double feedback, and the low-
frequency gain is adjusted according to the following
R4
G = 1 +
R5
The flat frequency response can be adjusted by changing the
size of R4. The size of R4 determines the transconductance
(gm) of the OTA and the open-loop gain of the amplifier.
RECOMMENDED COMPONENT VALUES
GAIN
R1
R2
R4
R5
IQ
RQC
1
2
150Ω
150Ω
47Ω
220Ω
220Ω
56Ω
300Ω
270Ω
200Ω
—
20mA
20mA
20mA
250Ω
250Ω
250Ω
270Ω
22Ω
10
equation:
R3
2R5
+5V
–5V
R2
R3
C1
5
6
1
1
Out
RQC
470p
10n
470p
10n
8
2
R1
3
R4
R5
In
2.2µ
2.2µ
IN4007
7
4
FIGURE 5. Block Diagram of the Test Fixture Current-Feedback Amplifier.
3
®
DEM-OPA660-5G
FIGURE 6. Silk Screen and Board Layouts of the Current-Feedback Amplifier.
R2
R4
5
6
1
BUF Out
R6
+5V
–5V
Either
or
R2
1
R7
RQC
470p
10n
470p
10n
Out
8
2
R1
R3
R8
3
In
2.2µ
2.2µ
IN4007
R5
7
4
FIGURE 7. Block Diagram of the Test Fixture Direct-Feedback Amplifier.
G = 1 +
The inputs of the OPA660 are protected by internal diode
clamps. These protection diodes can safely, continuously
conduct 10mA (30mA peak). If input voltages can exceed
the power supply voltages by 0.7V, then the input signal
current must be limited.
Using an emitter compensation technique parallel to R5, it is
possible to achieve both excellent pulse responses and band-
widths of up to more than 500MHz at 1.4Vp-p output
voltage. The RC combination parallel to R5 increases the
closed-loop gain at high frequencies. The PDS of the OPA660
shows an application circuit with gain of 3, as well as
presenting a bandwidth diagram and small- and large-signal
pulse responses.
The buffer output is not current-limited or protected. If the
output is shorted to ground, current of up to 60mA could
flow. Momentary shorts to ground (a few seconds) should be
avoided, but are unlikely to cause permanent damage. The
same cautions apply to the OTA section when connected as
a buffer.
The subsequent buffer amplifier decouples the relatively
high-impedance collector when driving low-impedance load
resistances. The board layout for the Direct-Feedback Am-
plifier configuration is illustrated in Figure 8.
BASIC CONNECTIONS
Figure 9 shows basic connections required for operation.
Power supply bypass capacitors should be located as close
as possible to the device pins. Solid tantalum capacitors are
generally best. A resistor (25Ω to 200Ω) in series with the
buffer and/or B input may help to reduce oscillations and
peaking.
APPLICATION INFORMATION
The OPA660 operates from ±5V power supplies (±6V
maximum). Do not attempt to operate with larger power
supply voltages, as permanent damage may occur.
®
4
DEM-OPA660-5G
Current vs Temperature). This variation of current with
temperature holds the transconductance, gm, of the OTA
relatively constant with temperature.
QUIESCENT CURRENT CONTROL PIN
The quiescent current of the OPA660 is set with the resistor
RQ connected from Pin 1 to –VCC. It affects the operating
currents of the buffer and OTA sections, thus controlling the
bandwidth and AC behavior as well as the transconductance
of the OTA section.
TEST CONFIGURATION
When testing the AC parameters of RF components,
impedance matching is necessary at the input and output of
the DUT. Double termination of the transmission cables
between the signal and DUT and between DUT and analyzer
is the cleanest way to drive, since reflections are absorbed on
both ends of the cable. The output resistance between the
amplifier’s output and the OUT socket should be equal to the
characteristic impedance minus the output impedance of the
amplifier. In turn, the input of the DUT should be terminated
by the characteristic cable impedance. Figure 11 shows a
typical test configuration.
RQC = 250Ω sets approximately 20mA total quiescent cur-
rent at 25°C. With a fixed 250Ω resistor, process variations
could cause this current to vary from approximately 16mA
to 26mA. It may be appropriate in some applications to trim
this resistor to achieve the desired quiescent current or AC
performance.
With a fixed RQC resistor, the quiescent current increases
with temperature (see typical performance curve, Quiescent
FIGURE 8. Silk Screen and Board Layouts of the Direct-Feedback Amplifier.
+5V(1)
RQC = 250Ω
sets roughly
1
IO ≈ 20mA
8
7
6
5
470pF
10nF
IQ Adjust
1
2
3
4
8
7
6
5
C
2
RQC
250Ω
E
B
V+ =+5V
Out
+
2.2µF
+1
3
Solid
Tantalum
+1
–5V(1)
470pF
4
10nF
V– = –5V
In
2.2µF
+
NOTE: (1) VCC = ±6V absolute maximum.
Solid
Tantalum
FIGURE 9. Basic Connections.
FIGURE 10. Pin Configuration.
®
DEM-OPA660-5G
5
Network Analyzer
50Ω
50Ω
50Ω
In
Out
DUT
50Ω
50Ω
• • •
Generator
FIGURE 11. Test Configuration.
ORDERING INFORMATION
ABSOLUTE MAXIMUM RATINGS
MODEL
DESCRIPTION
TEMPERATURE RANGE
Power Supply Voltage ........................................................................ ±6V
Input Voltage(1) ...................................................................... ±VCC, ±0.7V
Operating Temperature .................................................. –40°C to +85°C
Storage Temperature.................................................... –40°C to +125°C
Junction Temperature ................................................................... +150°C
Lead Temperature (soldering,10s) ............................................... +300°C
DEM-OPA660-5G
Layouts for all
applications using DIP
packages, unassembled
–25°C to +85°C
NOTE: (1) Inputs are internally diode-clamped to ±VCC
.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.
®
6
DEM-OPA660-5G
相关型号：
DEM-PCM1717/DEM-PCM1717-1/DEM-DAI1717
DEM-PCM1717. DEM-PCM1717-1. DEM-DAI1717 - EVALUATION FIXTURE
ETC
©2020 ICPDF网 联系我们和版权申明