EL2142C
Differential Line Receiver
Applications Information
2142-8
Gain Equation
e
e
a
c
c
a
(V -V V ) when R1 tied to GND
IN INB REF
V
OUT
((R2 R1)/R1)
a
((R2 R1)/R1)
V
(V -V ) when R1 tied to V
IN INB
OUT
REF
Choice of Feedback Resistor
For a gain of one, V may be shorted back to
Capacitance Considerations
As with many high bandwidth amplifiers, the
EL2142C prefers not to drive highly capacitive
OUT
V
FB
, but 100X–200X improves the bandwidth.
For gains greater than one, there is little to be
gained from choosing resistor R1 value below
200X, for it would only result in increased power
dissipation and potential signal distortion. Above
200X, the bandwidth response will develop some
peaking (for a gain of one), but substantially
higher R1 values may be used for higher voltage
gains, such as up to 1 kX at a gain of four before
peaking will develop.
loads. It is best if the capacitance on V
is
OUT
kept below 10 pF if the user does not want gain
peaking to develop. The V node forms a poten-
FB
tial pole in the feedback loop, so capacitance
should be minimized on this node for maximum
bandwidth.
The amount of capacitance tolerated on any of
these nodes in an actual application will also be
dependent on the gain setting and the resistor
values in the feedback network.
5
ELANTEC [ ELANTEC SEMICONDUCTOR ]
