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2006 Conference Best Paper Awards
Best Student Paper
Kurahashi,
Hanumolu, Temes, and Moon from Oregon
State University won the Best Student Paper award for their work “A
0.6V Highly Linear Switched-R-MOSFET-C Filter”. The switched-R-MOSFET-C (SRMC) filter
falls into the category of filters that use variable timing to adjust
circuit time-constants.
Specifically, it exploits a clock with variable duty-cycle to
switch the MOSFET between full ON and OFF in the R-MOSFET branch, thus tuning
the equivalent, average resistance.
The tuning range, which is determined by the duty cycle of the
clock, becomes independent of the supply voltage and makes SRMC well suitable
for low-voltage operation. In
addition, high linearity is achieved by the MOSFET ON resistance being much
smaller than the branch resistor.
It is further enhanced by placing the tuning MOSFET in the
feedback loop. The paper  presents a detailed circuit design of
SRMC implementation in a 2nd order Butterworth low-pass filter
fabricated in a 0.18 µm CMOS technology. Measurement confirms the excellent
performance of the SRMC filter exhibiting -77db THD at 0.6V supply
voltage and -90db THD at 0.8V for a 0.6Vpp differential 2kHz sine
input.
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