A 400-MHz super-regenerative receiver with digital calibration for capsule endoscope systems in 0.18-μm CMOS

A low-power super-regenerative receiver (SR-RX) with a digitally-controlled oscillator for the capsule endoscope system is reported in this paper. In this work, an open-loop frequency calibration loop is proposed to adjust the oscillator center frequency to the desired frequency band. The RX operates in the 402–405 MHz MICS band, and is designed to receive on-off keying modulation signal. This chip was fabricated in the TSMC 0.18-μm CMOS process. The RX start-up time is only 14.8 μs and is capable of a maximum data rate of 1 Mbps. The SR-RX consumes 5.5 mW from a 1.5-V supply voltage.