Data Sheet

AD829

Rev. I | Page 15 of 20

Figure 44 and Figure 45 show the closed-loop frequency

response of the AD829 for different closed-loop gains and

different supply voltages.

Figure 44. Closed-Loop Frequency Response for the Inverting Amplifier Using

Current Feedback Compensation

Figure 45. Closed-Loop Frequency Response vs. Supply for the Inverting

Amplifier Using Current Feedback Compensation

When a noninverting amplifier configuration using a current

feedback compensation is needed, the circuit shown in Figure 46 is

recommended. This circuit provides a slew rate twice that of the

shunt compensated noninverting amplifier of Figure 47 at the

expense of gain flatness. Nonetheless, this circuit delivers 95 MHz

bandwidth with 1 dB flatness into a back-terminated cable,

with a differential gain error of only 0.01% and a differential

phase error of only 0.015 at 4.43 MHz.

Figure 46. Noninverting Amplifier Connection Using Current Feedback

Compensation

Figure 47. Video Line Driver with a Flatness over Frequency Adjustment

LOW ERROR VIDEO LINE DRIVER

The buffer circuit shown in Figure 47 drives a back-terminated

75 Ω video line to standard video levels (1 V p-p), with 0.1 dB

gain flatness to 30 MHz and with only 0.04° and 0.02% differential

phase and gain at the 4.43 MHz PAL color subcarrier frequency.

This level of performance, which meets the requirements for

high definition video displays and test equipment, is achieved

using only 5 mA quiescent current.

FREQUENCY (MHz)

1

10

–15

–12

–9

–6

–3

0

3

6

9

12

15

100

GAIN = –4

CCOMP = 2pF

GAIN = –2

CCOMP = 3pF

GAIN = –1

CCOMP = 4pF

VS = ±15V

RL = 1kΩ

RF = 1kΩ

VIN = –30dBm

FREQUENCY (MHz)

1

10

–47

–44

–41

–38

–35

–32

–29

–26

–23

–20

–17

100

±5V

±15V

VIN = –20dBm

RL = 1kΩ

RF = 1kΩ

GAIN = –1

CCOMP = 4pF

3

2

7

6

4

5

+

–

AD829

+15V

–15V

0.1

µF

3pF

CCOMP

2k

Ω

2k

Ω

0.1

µF

50

Ω

50k

Ω

50

Ω

50

Ω

COAX

CABLE

50

Ω

COAX

CABLE

VIN

VOUT

3

2

7

6

5

4

+

–

AD829

+15V

0.1

µF

30pF

CCOMP

–15V

0.1

µF

300

Ω

300

Ω

75

Ω

75

Ω

75

Ω

50

Ω

COAX

CABLE

VIN

VOUT

OPTIONAL

2pF TO 7pF

FLATNESS

TRIM