A low-power noncoherent BPSK demodulator for implantable medical devices

A fully-integrated non-coherent BPSK demodulator intended for implantable medical devices is presented. Places of every 180 degrees phase transitions in BPSK modulated signals are recognized using active high-pass filters as negative and positive sharp pulses with adequate amplitude. In order to recover the initial base-band data, the sharp pulses are converted to digital level pulses using an op-amp based Schmitt trigger circuit. For a data rate of 1 Mbps and carrier frequency of 1 MHz, the proposed demodulator achieved a 100% data rate to carrier frequency ratio. Designed in a 0.18 μm standard CMOS technology, it consumes only 49 μA from a 1.8 V supply.