can be used. For single ended sensing a fixed reference capacitor can be used.
Capacitive sensing can use ac analog or digital techniques. Microminiature pressure
sensors can use piezoresistive strain gauge sensing or capacitive sensing
techniques. Being a semiconductor-based technology, the sensor signal is conditioned
on the die, i.e., amplified, impedance matched, linearized, and temperature
compensated.
Figure 12.12b shows an ac bridge with offset and span conditioning that can
be used with capacitive sensing. Initially, the bridge is balanced for zero offset
with potentiometer R3, the output from the bridge is amplified and buffered. The
output amplitude can be adjusted by the gain control, R5. The signal will need
to be converted to a dc signal and further amplified for transmission.