
Advanced Switched-Capacitor Circuit Techniques
261
In the output offset storage confi guration shown in Figure 7.8(b), an open-loop
op-amp is employed as a buffer. When Φ
1
is on, the offset voltage is amplifi ed, and
the result is sampled by the output capacitor C. Next, Φ
2
is on, (V
in
− V
off
) is ampli-
fi ed, and the result is sampled by C. So ideally the output voltage on the left plate of
C is also given by V
in
− V
off
+ V
off
= V
in
.
As compared to its input offset storage counterpart, the output offset storage
confi guration is typically faster due to the use of an open-loop op-amp. However, the
value of A
0
has to be rather small (usually less t