Asynchronous delta-sigma modulator with multiple-valued output

In this paper, a continuous-time asynchronous delta-sigma (ΔΣ) modulator (ADSM) is proposed. The proposed circuit is multiple-valued output. The circuit is consists of hysteresis comparator, operational transconductance amplifier, and digital-to-analog circuits. Next, an example circuit of 5-level ADSM is discussed and simulated. An analog-to-digital converter consisted of the 5-level ADMS and multiple-valued logic decoder and digital counter is presented and simulated. All of the proposed circuits are simulated in transistors level through HSPICE with set of 2.0μm CMOS process parameters. Detailed simulation results are shown in this paper.