High Stability Gain Structure and Filter Realization with less than 50 ppm/° C Temperature Variation with Ultra-low Power Consumption using Switched-capacitor and Sub-threshold Biasing

This paper presents the design of an ultra-low power subthreshold Gm stage where transconductance is very stable with process, temperature, and voltage variations. This technique is used to design a differential amplifier with constant gain and a second order biquad filter with constant cut off frequency. The amplifier gain achieves a small temperature coefficient of 48.6 ppm/°C and exhibits small sigma of 75 mdB with process. The second order biquad achieves temperature stability of 69 ppm/°C and a voltage coefficient of only 49 ppm/mV.