AD8003

Data Sheet

Rev. C | Page 12 of 16

APPLICATIONS INFORMATION

GAIN CONFIGURATIONS

Unlike conventional voltage feedback amplifiers, the feedback

resistor has a direct impact on the closed-loop bandwidth and

stability of the current feedback op amp circuit. Reducing the

resistance below the recommended value can make the amplifier

response peak and can even become unstable. Increasing the

size of the feedback resistor reduces the closed-loop bandwidth.

Table 5 provides a convenient reference for quickly determining

the feedback and gain set resistor values, and the small and

large signal bandwidths for common gain configurations. The

feedback resistors in Table 5 have been optimized for 0.1 dB

flatness frequency response.

Table 5. Recommended Values and Frequency Response1

Gain

−3 dB

SS BW

(MHz)

Large

Signal

−3 dB

BW

Large

Signal

0.1 dB

BW

−1

300

300

0

734

668

--

+1

432

N/A

24.9

1650

822

--

+2

464

464

0

761

730

190

+5

300

75

0

567

558

165

+10

300

33.2

0

446

422

170

1

Figure 38 and Figure 39 show the typical noninverting and inverting

configurations and recommended bypass capacitor values.

FB

AD8003

10µF

0.1µF

–

+

+V

–V

10µF

0.1µF

Figure 38. Noninverting Gain

FB

AD8003

10µF

0.1µF

–

+

+V

–V

10µF

0.1µF

Figure 39. Inverting Gain

RGB VIDEO DRIVER

Figure 40 shows a typical RGB driver application using bipolar

464 Ω. The amplifier inputs are terminated with shunt 75 Ω

resistors, and the outputs have series 75 Ω resistors for proper

video matching. In Figure 40, the POWER DOWN pins are not

shown connected to any signal source for simplicity. If the power-

down function is not used, it is recommended that the POWER

DOWN pins be tied to the positive supply and not be left floating

(not connected).

In applications that require a fixed gain of +2, as previously

mentioned, the designer may consider the ADA4862-3.

The ADA4862-3 is another high performance triple current

feedback amplifier. The ADA4862-3 has integrated feedback

and gain set resistors that reduce board area and simplify designs.

10µF

0.1µF

10µF

0.1µF

10µF

0.1µF

10µF

0.1µF

75

Ω

75

Ω

21

22

19

24

464

Ω

75

Ω

464

Ω

75

Ω

PD1

3

2

4

PD2

PD3

1

10µF

0.1µF

75

Ω

75

Ω

16

17

15

18

13

5

23

14

10µF

0.1µF

6

464

Ω

464

Ω

20

464

Ω

464

Ω

AD8003

Figure 40. RGB Video Driver