Integrated Low Pass Filter for M-Sequence UWB Radars

This paper deals with the design of an active low pass filter for M-sequence UWB radars. The proposed filter realized in the form of an application-specific integrated circuit uses a modified Sallen-Key topology, exploiting a Cherry-Hooper amplifier in place of an operational amplifier and employs varactors enabling the tuning of the filter cutoff frequency. The feasibility of the concept is proven by simulation and on-die measurement results. According to the measurements, the low pass filter with nominal cutoff frequency of 1 GHz and slope of 10 dB per octave was obtained in the cost-efficient 0.35 μm SiGe BiCMOS technology which is suitable for the integration of the whole M-sequence radar system on a single chip.