A 2.7-V elliptical MOSFET-only g/sub m/C-OTA filter

The g/sub m/C-operational transconductance amplifier (OTA) technique relaxes transconductor output swing and dc-gain requirements, which makes it a suitable candidate for low-voltage circuits. To reduce the power consumption of OTA's, an excess phase shift compensation with an automatic tuning circuit is used. A floating triode-region transconductor with a novel biasing to compensate the effect of channel-length modulation is presented. The two independent common-mode levels in a g/sub m/C-OTA integrator are utilized to bias a pMOS as a linear capacitor. This enables the realization of the floating-transmission zero capacitors with a pure digital CMOS process. The implementation and the experimental results for a third order 2.7-V all-MOS elliptical filter with 64-dB dynamic range and 0.1% linearity are presented.