FMCW radar ramp leakage compensation via closed loop DC correction

This paper describes a novel method for compensating ramp leakage in frequency modulated continuous wave (FMCW) radar applications that is not canceled by deramping. With a closed loop compensation algorithm it is possible to increase the signal to leakage ratio of common single chip FMCW radars by orders of magnitude in ideal situations. The loop consists of a DC-coupled FMCW radar frontend including a baseband amplifier, analog to digital converter (ADC), the DC-component of a Fast Fourier Transform (FFT), a digital to analog converter (DAC) and an active offset compensation for the baseband amplifier. The resulting gain in signal quality can be used to decrease the total system cost by use of cheaper ADC´s, decrease the complexity of signal processing or decrease the false alarm rate. Other advantages of this system include treatment of the frontend as black box, high configurability of the baseband frequency response curve and decreased noise floor.