13

®

OPA627, 637

OPA627

OPA637

2k

Ω

500

Ω

6pF

4pF

Error Band

±0.5mV

±0.2mV

(0.01%)

depending on test fixture layout. Once optimum value is

determined, a fixed capacitor may be used.

FIGURE 12. High Speed Instrumentation Amplifier, Gain = 100.

–In

+In

+

–

OPA637

Differential Voltage Gain = 1 + 2R

2

3

–

+

–

+

INA105

Differential

Amplifier

1

6

5

Output

Gain = 100

CMRR

116dB

Bandwidth

1MHz

OPA637

25k

Ω

25k

Ω

25k

Ω

25k

Ω

Input Common-Mode

Range = ±5V

≈

≈

3pF

R

F

5k

Ω

R

F

5k

Ω

R

G

101

Ω

–

+

±5V

Out

+15V

2k

Ω

C

F

2k

Ω

Error Out

R

I

R

I

51

Ω

–15V

HP-

5082-

2835

High Quality

Pulse Generator

/

FIGURE 11. Settling Time and Slew Rate Test Circuit.

FIGURE 14. Composite Amplifier for Wide Bandwidth.

This composite amplifier uses the OPA603 current-feedback op amp to

provide extended bandwidth and slew rate at high closed-loop gain. The

feedback loop is closed around the composite amp, preserving the

precision input characteristics of the OPA627/637. Use separate power

supply bypass capacitors for each op amp.

GAIN

–3dB

SLEW RATE

(V/V)

OP AMP

(

Ω)(kΩ)(Ω)(kΩ) (MHz)

(V/

100

OPA627

4.99

20

1

15

700

1000

OPA637

49.9

4.99

12

1

11

500

NOTE: (1) Closest 1/2% value.

*Minimize capacitance at this node.

FIGURE 13. High Speed Instrumentation Amplifier, Gain = 1000.

+

–

OPA603

–

+

A

1

R

3

R

1

R

4

R

2

V

I

V

O

*

R

for ±10V Out

–In

+In

+

–

OPA637

Differential Voltage Gain = (1 + 2R

2

3

–

+

–

+

INA106

Differential

Amplifier

1

6

5

Output

Gain = 1000

CMRR

116dB

Bandwidth

400kHz

OPA637

10k

Ω

10k

Ω

100k

Ω

100k

Ω

Input Common-Mode

Range = ±10V

≈

≈

3pF

R

F

5k

Ω

R

F

5k

Ω

R

G

101

Ω