Ultra low power wide-band mixer circuit based on subthreshold operation for MB-OFDM UWB

Abstract

This paper presents an extremely low power down-conversion mixer based on subthreshold operation for MB-OFDM UWB receiver, for the first band of operation 3.1–3.628GHz. The proposed down-conversion mixer uses a double balanced Gilbert cell to provide the required performance in the conversion gain (CG) and the isolation among ports. It includes an input matching network (IMN) to enhance the input matching of the mixer. The proposed mixer is designed such that all transistors work in subthreshold regime under a supply voltage of 0.5V, thus resulting in extremely low power consumption. We implemented the proposed mixer using a 0.18μm CMOS process. Simulation experiments show that the conversion gain of the mixer is 2.17–3.25dB over the frequency range of 3.1–3.628GHz when IF port is terminated with 50Ω. The noise figure of the mixer is 5.12–5.93dB, while the LO-IF isolation is lower than −111dB. The 1-dB compression point is −16.68dBm, third-order input intercept point IIP3 is −5.7dBm. The experiments show that the proposed design consumes only 6.6uW at 0.5V, which is extremely low power compared with existing work.