Low-Voltage Low Noise Figure Down-Conversion Mixer for Band #1 of MB-OFDM System in 180 nm Complementary Metal Oxide Semiconductor Technology

Abstract

Low-voltage design is a challenge for Gilbert cell-based mixers due to stacking transconductance and switching stage. This work addresses this issue by proposing a design of a low-voltage down-conversion mixer for band #1 of multiband orthogonal frequency division multiplexing (MB-OFDM) system in 180 nm complementary metal oxide semiconductor (CMOS) technology. The mixer is tuned at band #1 at RF frequency of 3.432 GHz and IF frequency of 264 MHz. The proposed mixer uses folded cascode connection of LO and RF in order to increase headroom and to reduce the DC supply voltage for low-voltage operation. Common gate configuration is used at RF transconductance stage to enhance the input bandwidth of the mixer. RF and LO ports are matched to 50 Ω using differential T and LC matching, respectively. The resistive source denegation technique is used to linearize transconductance with respect to the bias point. The common source stage is used at the IF port as a buffer cum matching circuit it. The simulation results of the mixer show the maximum conversion gain of 9.76 dB, 1 dB compression point (P1dB) of -16.25 dBm, the third-order input intercept point (IIP3) of -4.70 dBm, an SSB noise figure of 9.036 dB, and S11of -19.490 dB at the supply voltage of 1.2 V. Excluding off chip components, proposed mixer records an active area of 926.35 μm2.