MAX4158/MAX4159/MAX4258/MAX4259
350MHz/250MHz, 2-Channel
Video Multiplexer-Amplifiers
______________________________________________________________________________________ 13
Driving Capacitive Loads
A correctly terminated transmission line is purely resis-
tive and presents no capacitive load to the amplifier.
Consequently, the MAX4158/MAX4159/MAX4258/
MAX4259 are optimized for AC performance and are
not designed to drive highly capacitive loads. Reactive
loads will decrease phase margin and may produce
excessive ringing and oscillation (see
Typical
Operating Characteristics
). The circuit of Figure 4
reduces this problem. The small (usually 5Ω to 20Ω)
isolation resistor R
ISO
, placed before the reactive load,
prevents ringing and oscillation. At higher capacitive
loads, AC performance is limited by the interaction of
load capacitance with the isolation resistor.