Analog Baseband Filter and Variable-gain Amplifier for Automotive Radars in 22 nm FD-SOI CMOS

This paper presents the design of an analog baseband for a 77GHz automotive radar in 22 nm fully-depleted silicon on insulator (FD-SOI) CMOS. The baseband ranges from 0.13 MHz to 14 MHz and requires a steep low-pass filter to avoid aliasing. This is realized with an 8th order Butterworth lowpass filter. In order to achieve the specified gain requirements, a variable gain amplifier (VGA) with DC-offset cancellation is applied before the filter. Its dynamic range was maximized, the optimization strategy is presented. The performance of the baseband components was verified with laboratory measurements. The filter achieves a suppression of >=35 dB at 28 MHz. A dynamic range of 45 dB and a maximum gain of 41 dB is measured for the VGA. In addition, a good agreement between simulation and measurement is obtained. With an area-optimized design of 0.032 mm(exp 2), the baseband components are a fraction of the size compared to chains of similar radar systems.