AD713 Analog Devices, AD713 Datasheet - Page 14

• 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

AD713
CMOS DAC APPLICATIONS
The AD713 is an excellent output amplifier for CMOS DACs. It
can be used to perform both two- and four-quadrant operation.
The output impedance of a DAC using an inverted R-2R ladder
approaches R for codes containing many 1s, 3R for codes
containing a single 1, and infinity for codes containing all 0s.
For example, the output resistance of the
between 11 kΩ and 33 kΩ. Therefore, with the DAC’s internal
feedback resistance of 11 kΩ, the noise gain varies from 2 to
4/3. This changing noise gain modulates the effect of the input
offset voltage of the amplifier, resulting in nonlinear DAC
amplifier performance. The AD713, with its guaranteed 1.5 mV
input offset voltage, minimizes this effect, achieving 12-bit
performance.
Figure 42 and Figure 43 show the AD713 and a 12-bit CMOS
DAC, the AD7545, configured for either a unipolar binary (two-
quadrant multiplication) or bipolar (four-quadrant multiplication)
operation. Capacitor C1 provides phase compensation, which
reduces overshoot and ringing.
Table 5. Recommended Trim Resistor Values vs. Grades for
AD7545 for V
Trim Resistor
R1
R2
D
= 5 V
JN/AQ
500 Ω
150 Ω
*REFER TO TABLE 5.
V
IN
KN/BQ
200 Ω
68 Ω
ADJUST
GAIN
R1*
19
V
LN/CQ
100 Ω
33 Ω
REF
DGND
AD7545
3
V
V
18
DD
DD
AD7545
DB11 TO DB0
DATA INPUT
modulates
R
12
20
FB
GLN/GCQ
20 Ω
6.8 Ω
AGND
OUT1
Figure 43. Bipolar Operation
R2*
Rev. F | Page 14 of 20
2
1
COMMON
ANALOG
C1
33pF
1/4
AD713
+15V
4
0.1µF
FILTER APPLICATIONS
A Programmable State Variable Filter
For the state variable or universal filter configuration of Figure 44
to function properly, DAC A1 and DAC B1 must control the
gain and Q of the filter characteristic, and DAC A2 and DAC B2
must accurately track for the simple expression of f
This is readily accomplished using two
AD713 quad op amp. Capacitor C3 compensates for the effects
of op amp gain bandwidth limitations.
This filter provides low-pass, high-pass, and band-pass outputs
and is ideally suited for applications where microprocessor
control of filter parameters is required. The programmable
range for component values shown is f
Q = 0.3 to 4.5.
V
*REFER TO TABLE 5.
IN
ADJUST
GAIN
R1*
10kΩ
1%
R3
DB11 TO DB0
19
R4
20kΩ
1%
V
REF
Figure 42. Unipolar Binary Operation
1/4
AD713
–15V
V
V
AD7545
11
18
DD
DD
20kΩ
1%
R5
0.1µF
DGND
3
R
20
FB
AGND
OUT1
V
R2*
OUT
1
2
COMMON
ANALOG
C
AD7528
= 0 kHz to 15 kHz and
C1
33pF
1/4
AD713
+15V
–15V
11
4
0.1µF
DACs and one
0.1µF
C
to be true.
V
OUT