A 2-V CMOS 455-kHz FM/FSK demodulator using feedforward offsetcancellation limiting amplifier

This paper presents a low-voltage low-power IF 455-kHz signal processor that contains a three-stage limiting amplifier and an FM/FSK demodulator. The limiting amplifier uses an on-chip feedforward offset cancellation circuit. The FM/FSK demodulator employs a quadrature detector that is composed of an on-chip phase detector and an external tank phase shifter. The demodulation constant is 20 mV/kHz with masimum ±10-kHz frequency deviation. The IF signal processor that consumes 2.3 mW from a single 2-V power supply demonstrates a high sensitivity of -72 dBm. It occupies an active area of 0.2 mm² using 0.6-μm digital CMOS technology