Modified Gilbert-Cell Mixer With an LO Waveform Shaper and Switched Gate-Biasing for 1/f Noise Reduction in 28-nm CMOS

In this brief, we propose an active mixer based on a modified Gilbert-cell topology intended for radar applications, which uses an LO waveform shaper at mm-wave frequencies to decrease the high 1/f noise of MOS transistors. Compared to a reference mixer without an LO waveform shaper, measurement results show that this mixer achieves a significant 5 dB noise figure (NF) reduction at 100 kHz. The measured voltage conversion gain (CG) and input-referred 1-dB compression point (IP1dB) are 2 dB and -4 dBm, respectively. The core of the proposed modified Gilbert-cell draws 13 mA from a single 0.9-V supply, while it occupies an area of 0.5 mm x 0.94 mm. Additionally, an IF buffer drawing 12 mA has been added to drive a 50 Omega load for measurement purposes. To the best of author's knowledge, we apply the principle of switched biasing for 1/f noise reduction of an active mixer at mm-wave frequencies for the first time.