Low Power Frequency-Shift Keying Demodulators for Biomedical Implants

This Low power frequency-shift keying (FSK) demodulators are presented for the biomedical implants. Two FSK demodulators are designed with different concepts. The analog FSK (A-FSK) demodulator is composed of a single balance mixer, a square wave generator, a charge pump circuit, and a comparator to achieve the demodulation. The other digital FSK (D-FSK) demodulator employs only one block which the output signals for stimulating can be obtained simply and directly. Both demodulators are implemented by tsmc 1P6M CMOS process at IV supply voltage. A-FSK demodulator occupies chip area of 0.016 mm
²
. The data rate is 2.5Mbps while receiving 2.5MHz/5MHz FSK carrier signals. While receiving 5MHz/10MHz FSK carrier signals, the data rate of the D-FSK demodulator is up to be 5Mbps. The D-FSK demodulator occupies 0.004mm
²
. The power consumption of the A-FSK and D-FSK demodulators are 0.47mW and 0.022mW, respectively.