
Advanced Switched-Capacitor Circuit Techniques
255
In [16], a current source is used to drive a replica switch with a constant on-
conductance (g
ds
), and an op-amp loop is used to force the source of the replica
switch to track the input signal, thereby allowing the main switch to maintain a
constant V
gs
, and also, a fi xed g
ds
. As a result, the distortion caused by the input-
dependent on-resistance (R
on
) is greatly suppressed. However, due to the use of active
devices such as the op-amp, this bootstrapping circuit dissipates more power as
compared to the aforementioned passive confi gurations, given the same power supply
voltage.
Switched Op-Amp ...