
Advanced Switched-Capacitor Circuit Techniques
251
standby mode), then it can be shown that the average power dissipation is given by
[6]
PkTDRf
V
V
N
in
dd
=
(
)
4 (7.2)
where DR represents the dynamic range (i.e., accuracy), f
N
is the Nyquist signal
bandwidth (i.e., speed), and V
dd
is the power supply voltage. Thus, in contrast to a
digital CMOS IC whose power dissipation decreases in proportion to the square of
V
dd
, an analog CMOS IC may actually consume more power as the supply voltage is
lowered.
Special CMOS process techniques such as the multiple-layer masking [7] can be
used to reduce the threshold voltage of the MOS transistor. Also, the fl oati ...