A CMOS PWM Transceiver Using Self-Referenced Edge Detection

A CMOS pulsewidth modulation (PWM) transceiver circuit that exploits the self-referenced edge detection technique is presented. By comparing the rising edge that is self-delayed by about 0.5 T and the modulated falling edge in one carrier clock cycle, area-efficient and high-robustness (against timing fluctuations) edge detection enabling PWM communication is achieved without requiring elaborate phase-locked loops. Since the proposed self-referenced edge detection circuit has the capability of timing error measurement while changing the length of self-delay element, adaptive data-rate optimization and delay-line calibration are realized. The measured results with a 65-nm CMOS prototype demonstrate a 2-bit PWM communication, high data rate (3.2 Gb/s), and high reliability (BER> 10^-12) with small area occupation (540 μm²). For reliability improvement, error check and correction associated with intercycle edge detection is introduced and its effectiveness is verified by 1-bit PWM measurement.