A Compact High Current Efficiency Low-Voltage MOS Transconductor with Nearly Constant Input Voltage Range

In this paper, a compact MOS linear voltage to current converter is proposed. The proposed transconductor is realized by connecting a simple MOS differential pair to the newly proposed square-root circuits. The resulting circuit is compact, can be operated under low supply voltage and has high current efficiency. The proposed transconductor were simulated by SPICE using model parameter for 0.35 μm fabrication process. The simulation results show that under 1.8V single supply, the proposed transconductor features ±0.4V linear range with very high current efficiency of 3.6 V^-1 while consumes 45μW of quiescent electrical power.

I. Introduction

Linear transconductors are basic building blocks in the design of continuous-time signal processing circuits including Gm-C filters, data converters, variable gain amplifiers and other interface circuits. One of the common conflicts encountered in linear transconductor design is the interdependent between linear input range and transconductance gain, which potentially results in a limited degree of freedom in designing analogue systems [1]–[4]. In particular, as device sizes and supply voltages are scaled down, the design of CMOS transconductors with high linearity over a reasonable input range has become more challenging.