A 65 nm CMOS base band filter for 77 GHz automotive radar compensating path loss difference

In this paper, a baseband filter is proposed in order to maintain the constant sensitivity regardless of distance difference for 77 GHz automotive radar system. Using DCOC loop circuit, as well as removing DC offset noise, compensation of the received power difference depending on the distance is achieved. Measured results show that the maximum gain is 51 dB and high pass cutoff frequency can be tuned from 5 KHz to 15 KHz. The slope of high pass filter can be tuned from -10 to -40 dB/decade for the distance compensation. The measured IIP3 is + 4.5 dBm at 100 KHz with 4.3mA at 1.0V supply voltage. The fabricated die size 500 μm × 1050 μm excluding the in/out pads.