A Very Low Voltage Mixer for Baseband Wireless Sensor Applications

Abstract

An enhanced mixer topology suitable for very low supply voltage applications is developed. The circuit introduces a linear resistor network to the conventional mixer based on cross-coupled triode MOS transistors to render extended transistors’ operation and linearity improvement at a low supply. Detailed analysis that leads to a systematic design is outlined. The feasibility of the mixer for baseband wireless sensor applications is demonstrated through simulation of a 0.5-V demodulator for IEEE 802.15.4 radio using regular transistors in a 1.8V 0.18µm CMOS process with V_T0 = 0.4V which is as large as 80% of the supply voltage. Also provided to verify its practicality is the experimental demodulator at a reduced data rate based upon a breadboard implementation using array transistors.