AD5539

–11–

REV. B

220

Ω R

Ω source resistance, the noise gain will be

12.8, because the source resistance affects the noise gain.

Figures 31 and 32 show the small and large signal responses of

the circuit of Figure 29.

Figure 31. The Small-Signal Pulse Response of the Gain

Pin 12; Vertical Scale: 50 mV/div; Horizontal Scale:

5 ns/div

Figure 32. The Large-Signal Pulse Response of the Gain

Pin 12; Vertical Scale: 200 mV/div; Horizontal Scale:

5 ns/div

A Video Amplifier Circuit with 20 dB Gain (Terminated)

High gain applications (14 dB and up) require only a small lead

capacitance to obtain flat response. The 26 dB (20 dB termi-

nated) video amplifier circuit of Figure 33 has the response

shown in Figure 34 using only approximately 0.5-1 pF lead ca-

output or to Pin 12 with very little difference in response.

Figure 33. A 20 dB Gain Video Amplifier for 75

Ω Systems

Figure 34. Response of the 20 dB Video Amplifier

In color video applications, the quality of differential gain and

differential phase response is very important. Figures 35 and 36

show a circuit and test setup to measure the AD5539’s response

to a modulated ramp signal (0-90 IRE p-p ramp, 40 IRE p-p

modulation, 4.4 MHz).

Figures 37 and 38 show the differential gain and phase response.