Demystifying Switched Capacitor Circuits

Demystifying Switched-Capacitor Circuits

294

SC Integrators

The fi rst integrator is shown in Figure 8.16, and it operates as follows. During ck

1

,

the input voltage V

in

is sampled onto C

sampling

. During ck

2

, a charge proportional to

the voltage difference between V

in

and DAC reference voltage V

ref

is transferred from

C

sampling

to C

integrating

.

The sampling and integrating capacitances were specifi ed earlier in Table 8.4 and

are denoted here in Figure 8.16. The input common-mode voltage, V

cm_i

is set

to 0.9 V for a 2.5-V power supply, thereby allowing switches S

3

and S

4

to be

implemented using only NMOS devices. The sizing of the switches is listed ...