AD812

REV. B

–16–

Operation Using a Single Supply

The AD812 will operate with total supply voltages from 36 V

down to 2.4 V. With proper biasing (see Figure 53), it can be an

outstanding single supply video amplifier. Since the input and

output voltage ranges extend to within 1 volt of the supply rails,

it will handle a 1.3 V p-p signal on a single 3.3 V supply, or a

3 V p-p signal on a single 5 V supply. The small signal, 0.1 dB

bandwidths will exceed 10 MHz in either case, and the large

signal bandwidths will exceed 6 MHz.

The capacitively coupled cable driver in Figure 53 will achieve

outstanding differential gain and phase errors of 0.07% and 0.06

degrees respectively on a single 5 V supply. Resistor R2, in this

circuit, is selected to optimize the differential gain and phase by

operating the amplifier in its most linear region. To optimize the

circuit for a 3 V supply, a value of 8 k

Ω is recommended for R2.

AD812

8

4

R2

11.8k

75

75

R3

1k

75

CABLE

R1

9k

C1

2 F

C3

30 F

649

649

47 F

C2

1 F

Figure 53. Biasing for Single Supply Operation

8-Lead Plastic DIP

(N-8)

8

14

5

PIN 1

SEATING

PLANE

0.060 (1.52)

0.015 (0.38)

0.165

0.01

(4.19

0.25)

0.10

(2.54)

BSC

0.325 (8.25)

0.300 (7.62)

0.015 (0.381)

0.008 (0.204)

0.195 (4.95)

0.115 (2.93)

0.39 (9.91)

0.25

(6.35)

0.125 (3.18)

MIN

0.018

0.003

(0.46 +0.08)

0.033 (0.84)

NOM

8-Lead Plastic SOIC

(SO-8)

0.1968 (5.00)

0.1890 (4.80)

85

4

1

0.2440 (6.20)

0.2284 (5.80)

PIN 1

0.1574 (4.00)

0.1497 (3.80)

0.0688 (1.75)

0.0532 (1.35)

SEATING

PLANE

0.0098 (0.25)

0.0040 (0.10)

0.0192 (0.49)

0.0138 (0.35)

0.0500

(1.27)

BSC

0.0098 (0.25)

0.0075 (0.19)

0.0500 (1.27)

0.0160 (0.41)

8

0

0.0196 (0.50)

0.0099 (0.25)

45

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

–0.5

–3.0

1

10

1000

100

–1.0

–1.5

–2.0

–2.5

0

0.5

–270

–180

–90

0

FREQUENCY – MHz

–3.5

90

GAIN

PHASE

Figure 54. Closed-Loop Gain and Phase vs. Frequency,

Circuit of Figure 53

10

90

100

0%

500mV

1V

50ns

Figure 55. Pulse Response of the Circuit of Figure 53 with