A 6 Order Butterworth SC Low Pass Filter for Cryogenic Applications From -180oc to 120oc

This paper presents a sixth order Butterworth switched capacitor (SC) low pass filter with radiationhardened-by-design (RHBD) for cryogenic applications. Implemented in a 0.5μm SiGe BiCMOS technology, this cryogenic SC filter is capable of operating over an ultrawide temperature (UWT) range from -180oC to 120oC and under high-energy particle radiation environment on the lunar surface. This is the first SC filter, operating over 300oC temperature range with RHBD, reported so far. The measured results show that the filter approximates a sixth order Butterworth filter response in range of -180oC to 120oC. The clock-to-cutoff frequency ratio is 100:1. The clock feedthrough is less than 10uVRMS with single 3.3V supply. It consumes only 640uA at 200 kHz clock frequency current and occupies only 0.4x1.4 mm. Keyword: Butterworth, Switched capacitor, Low pass filter, RHBD, Cryogenic, Lunar-Mars, NASA