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Two-Stage Feedforward Class-AB CMOS OTA for Low-Voltage Filtering Applications
Phanumas KHUMSAT Apisak WORAPISHET
IEICE TRANSACTIONS on Electronics
Publication Date: 2007/12/01
Online ISSN: 1745-1353
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Electronic Circuits
operational transconductance amplifier, OTA, active-RC filters, MOSFET-C filters, feedforward,
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A compact OTA suitable for low-voltage active-RC and MOSFET-C filters is presented. The input stage of the OTA utilises the NMOS pseudo-differential amplifier with PMOS active load. The output stage relies upon the dual-mode feed-forward class-AB technique (based on an inverter-type transconductor) with common-mode rejection capability that incurs no penalty on transconductance/bias-current efficiency. Simulation results of a 0.5-V 100-kHz 5th-order Chebyshev filter based on the proposed OTA in a 0.18 µm CMOS process indicate SNR and SFDR of 68 dB and 63 dB (at 50 kHz+55 kHz) respectively. The filter consumes total power consumption of 60 µW.