A Novel Event-Based Method for ASK Demodulation

Abstract

This paper presents a novel ASK demodulation technique, using an Event-Based ADC (EB-ADC) and a digital ASK demodulation algorithm. The EB-ADC employs a minimalist Level Crossing Sample Scheme (LCSS) with only 2 levels, and uses a Time-to-Digital Converter (TDC) for measuring the time elapsed between two consecutive level crossings (events). The level crossing detection modules are composed of two strong-arm comparators. These comparators were characterized through an electrical simulation and then modeled in SystemVerilog in order to be integrated in a full digital simulation environment. The RF input signal of the testbench and its noise model have been modeled by replicating python's awgn function of commpy library. This demodulation technique takes advantage of the time measurement elapsed between two adjacent events, to apply a digital demodulation algorithm, for improving the symbol recognition performance and the noise resiliency, reaching for example a $\text{BER}=3.33\cdot 10^{-7}$ with a modulation index of 10%, a bit rate of 6.78 Mbps and a SNR of 16 dB. A circuit implementing this approach is currently in fabrication in FDSOI 28nm STMicroelectronics technology.