Counter-based CMOS QCWM demodulator for wide frequency range WPT biohealth applications

Abstract

In this paper, a CMOS QCWM demodulator was designed to achieve a wide carrier frequency range to cater for a variety of applications. Previous designs utilize a pulse to sawtooth peak (PW2SP) converter and a comparator that necessitates a reference voltage, causing the frequency range to be limited, due to the current starved nature of the PW2SP circuit. To address this issue, a modified PW2SP employing a programmable current mirror with a 3-bit counter was proposed to provide current programmability and eliminate the use of a voltage reference. The proposed QCWM demodulator was designed and fabricated on 180 nm CMOS technology. The current programmability allows the QCWM demodulator to reach data rate of 400Kb/s to 8Mb/s, when the carrier frequency is varied from 1 MHz to 20 MHz. The design consumes 209 $\mu$W at 20 MHz carrier frequency from a 1.4 V supply voltage with an energy consumption of 26.13 pJ/bit.