A 46-nF/10-MΩ Range 114-aF/0.37-Ω Resolution Parasitic- and Temperature-Insensitive Reconfigurable RC-to-Digital Converter in 0.18-μm CMOS

This paper presents a 46 nF/10MΩ-range, digital-intensive, reconfigurable RC-to-digital converter (R2CDC) that can readout multiple C and R sensors in a time-interleaved fashion. Ratio-metric conversion using swing-boosted period-modulation (SB-PM) front-end by the R2CDC results in 114 aFrms/0.37 Ω ᵣₘₛresolutions and a worst-case temperature-drift of 64.2 ppm/°C over −40 to 125°C. Femto-farad capacitances can be sensed with a relative code-deviation less than 0.16 % even when parasitics vary 30 times the baseline. Implemented in a0.18 ~μ mstandard CMOS process, the R2CDC consumes 140μ Afrom a 1 V supply, occupying an active area of0.175 ~μ m ².