COMPLETE VIDEO SYSTEM

Figure 3 above illustrates how an MSK 620 and MSK 643 can be used to build a compete video system for high voltage grid

drive. RA and RB act as a level shift stage to match the +3.9Vdc level at the output of the MSK 620 with the -1.55Vdc level at

the input of the MSK 643. The output of the MSK 643 is sampled and fed back to the MSK 620. This scheme provides black level

control superior to sampling the signal at pin 14 of the MSK 620. The general rule of thumb for transition times for a video driver

is that rising and falling edges should be no more than one third the pixel time of the monitor. To improve rise and fall time in the

system, the peaking capacitor Cp was added across the input resistor of the MSK 643. At high frequencies Cp increases the gain

of the amplifier there by causing peaking. Cp should be a variable capacitor so that the response of the amplifier can be fine tuned

for minimum transition time with minimum overshoot.

Rev. D 10/05

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