An ASK demodulator for data telemetry in biomedical application

This paper presents a demodulator design for Amplitude Shift Keying (ASK) based wireless telemetry system in biomedical application. It supports up to 300 Kbits per second (bps) data rate and detects envelope with modulation index of 1% or more. The design includes a single-to-differential OTA, a current mode full-wave rectifier, a log-domain peak detector, a variable-gain amplifier and a comparator. The rising and falling time constants of our design are tunable through varying off-chip components to support a wide range of modulation indexes and data rate. The circuit blocks are designed and simulated in Taiwan Semiconductor Manufacturing Company (TSMC) 0.18 mum process and occupying 120 times 420 mum
²
. The power consumption is 1 mW with 1.8 V supply voltage.