Environmental Engineering Reference
In-Depth Information
Distortion due to the nonlinear output conductance is effective at low
frequencies. Indeed, so long as the loop gain is high, signal (the
error
signal) is small, and distortion is mainly due to nonlinearities arising in the
output resistance
R
which is operated under large-signal conditions. For
increasing frequencies the compensation capacitor shunts the output
impedance to ground thereby reducing the weight of nonlinearities due to the
output resistance. Moreover, signal increases (due to the reduction in the
loop gain) and the nonlinear effects of the input transconductance become
more pronounced. Thus at high frequencies the amplifier is more adequately
modeled by the block diagram in Fig. 7.15, which includes normalised
nonlinear coefficients of the input transconductance
and
and
assumes the output resistance to be linear.
