A micropower class-AB CMOS log-domain filter for DECT applications

摘要

This paper presents a micropower second-order low-pass filternusing the log-domain principle and integrated in a 0.35-Μm CMOSnprocess. It has been designed as an antialiasing filter for a DECTntransceiver with a 45-kHz nominal cutoff frequency. The circuit usesntransistors biased in weak inversion without requiring separate wells.nIt operates at 1.5-V supply voltage and its current consumption is 8nΜA in idle mode. The log-domain filter is implemented with an on-chipnconditioner which allows class-AB operation. It can process inputncurrents at 5 kHz that are 25 times larger than the 200-nA bias current.nMeasurements up to 500 times the bias current have been done, since at 1nkHz the input current is only limited by the supply voltage