EL4095CS INTERSIL [Intersil Corporation], EL4095CS Datasheet - Page 13

• Manufacturer Part Number: EL4095CS
• Description: Video Gain Control/Fader/Multiplexer
• Manufacturer: INTERSIL [Intersil Corporation]

EL4095
FIGURE 3. LEVELING CIRCUIT WITH 0.5 ≤ A
≤ 2
V
Here the A input channel is configured for a gain of +2 and
the B channel for a gain of +1 with its input attenuated by
1/2. The connection is virtuous because the distortions do
not increase monotonically with reducing gain as would the
simple single-input connection.
For video levels, however, these constants can give fairly
high differential gain error. The problem occurs for large
inputs. Assume that a “twice-size” video input occurs. The A-
side stage sees the full amplitude, but the gain would be set
to 100% B-input gain to yield an overall gain of 1/2 to
produce a standard video output. The -V
of the A side is a
IN
buffer output that reproduces the input signal, and drives
R
and R
. Into the two resistors 2.1mA of error current
GA
FA
flows for a typical 1.4V of input DC offset, creating distortion
in a A-side input stage. R
and R
could be increased
GA
FA
together in value to reduce the error current and distortions,
but increasing R
would lower bandwidth. A solution would
FA
be to simply attenuate the input signal magnitude and
restore the EL4095 output level to standard level with
another amplifier so:
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