AD713 Analog Devices, AD713 Datasheet - Page 11

• Manufacturer Part Number: AD713
• Description: Precision, High Speed, BiFET Quad Op Amp
• Manufacturer: Analog Devices

Specifications of AD713

• -3db Bandwidth: 4MHz
• Slew Rate: 20V/µs
• Vos: 300µV
• Ib: 40pA
• # Opamps Per Pkg: 4
• Input Noise (nv/rthz): 16nV/rtHz
• Vcc-vee: 9V to 36V
• Isy Per Amplifier: 3mA
• Packages: DIP,SOIC

THEORY OF OPERATION
MEASURING AD713 SETTLING TIME
Figure 30 and Figure 31 show the dynamic response of the AD713
while operating in the settling time test circuit of Figure 29.
The input of the settling time fixture is driven by a flat-top pulse
generator. The error signal output from the false summing node
of A1, the AD713 under test, is clamped, amplified by Op Amp
A2, and then clamped again.
GENERATOR
EQUIVALENT
DYNAMICS
FLAT-TOP
PULSE
DATA
5109
OR
100
0%
90
10
• • • •
• • • •
2 ×
HP2835
Upper Trace: Output of AD713 Under Test (5 V/div),
Figure 30. Settling Characteristics 0 V to 10 V Step,
0.47µF
1.1kΩ
Lower Trace: Amplified Error Voltage (0.01%/div)
• • • •
• • • •
*
V
IN
5mV
5V
+
Figure 29. Settling Time Test Circuit
• • • •
• • • •
1µF
+
4.99kΩ
10kΩ
A2
–V
S
• • • •
• • • •
+V
0.2pF TO 0.8pF
0.1µF
5pF TO 18pF
S
200Ω
5pF
+
10kΩ
• • • •
• • • •
A1
–V
0.47µF
11
S
TO TEKTRONIX 7A26
SECTION (VIA LESS
• • • •
• • • •
+V
COAXIAL CABLE)
AD713
4
OSCILLOSCOPE
4.99kΩ
PREAMP INPUT
THAN 1FT 50Ω
10kΩ
S
1/4
206Ω
1µF
• • • •
• • • •
NOTES
1. USE CIRCUIT BOARD
+
WITH GROUND PLANE.
V
• • • •
• • • •
*USE VERY
ERROR × 5
SHORT CABLE
OR TERMINATION
RESISTOR
500ns
5kΩ
2 ×
HP2835
0.1µF
• • • •
• • • •
1MΩ
10pF
• • • •
• • • •
20pF
Rev. F | Page 11 of 20
The error signal is thus clamped twice: once to prevent overload-
ing amplifier A2 and then a second time to avoid overloading
the oscilloscope preamp. A Tektronix oscilloscope preamp
Type 7A26 was carefully chosen because it recovers from the
approximately 0.4 V overload quickly enough to allow accurate
measurement of the AD713 1 μs settling time. Amplifier A2 is a
very high speed FET input op amp; it provides a voltage gain of
10, amplifying the error signal output of the AD713 under test
(providing an overall gain of 5).
POWER SUPPLY BYPASSING
The power supply connections to the AD713 must maintain a
low impedance to ground over a bandwidth of 4 MHz or more.
This is especially important when driving a significant resistive
or capacitive load because all current delivered to the load
comes from the power supplies. Multiple high quality bypass
capacitors are recommended for each power supply line in any
critical application. As shown in Figure 32, a 0.1 μF ceramic and
a 1 μF electrolytic capacitor placed as close as possible to the
amplifier (with short lead lengths to power supply common)
assures adequate high frequency bypassing in most applications.
A minimum bypass capacitance of 0.1 μF should be used for
any application.
100
0%
90
10
• • • •
• • • •
Upper Trace: Output of AD713 Under Test (5 V/div),
Figure 32. Recommended Power Supply Bypassing
Lower Trace: Amplified Error Voltage (0.01%/div)
Figure 31. Settling Characteristics to –10 V Step,
• • • •
• • • •
5mV
5V
• • • •
• • • •
AD713
• • • •
• • • •
1/4
+V
–V
• • • •
• • • •
11
4
S
S
• • • •
• • • •
+
+
1µF
1µF
• • • •
• • • •
0.1µF
0.1µF
• • • •
• • • •
500ns
• • • •
• • • •
• • • •
• • • •
AD713