A 0.7V Fully Differential First Order GZTC-C filter

A 0.7 V supply voltage fully differential first order GZTC-C filter is herein proposed. The GZTC-C filter definition is used in this paper as a Transconductance-Capacitor filter (Gm-C) in which its gm stage is biased exactly on transconductance zero-temperature (GZTC) bias condition. This special bias point has all necessary conditions to design MOSFET transconductors with low temperature dependence. Additionally, two calibrate-points with three-bit resolution have been added to mitigate process variations which may cause bias shift errors on sensitive nodes, driving the circuit out of its normal GZTC operation region. The final circuit has been designed in a 130 nm CMOS process generating a 5 MHz cutoff frequency. The filter occupies around 0.01 mm
²
of silicon area while consuming just 21 μW. Monte Carlo (MC) post-layout and post-calibrated simulation has presented an Effective Cutoff Frequency Temperature Co-efficient (TC
_eff
) average of 73.4 ppm/°C with 30.6 ppm/°C standard deviation for a temperature range from -40 to +120°C and has estimated a cutoff frequency fabrication sensitivity of σ/μ = 0.87%, including average process and local mismatch variability.