Direct Mismatch Characterization of Femtofarad Capacitors

Hesham Omran, Rami T. ElAfandy, Muhammad Arsalan, Khaled N. Salama
2016 IEEE Transactions on Circuits and Systems - II - Express Briefs  
Reducing the capacitance of programmable capacitor arrays, commonly used in analog integrated circuits, is necessary for low-energy applications. However, limited mismatch data is available for small capacitors. We report mismatch measurement for a 2f F poly-insulator-poly (PIP) capacitor, which is the smallest reported PIP capacitor to the best of the authors' knowledge. Instead of using complicated custom onchip circuitry, direct mismatch measurement is demonstrated and verified using Monte
more » ... rlo Simulations and experimental measurements. Capacitive test structures composed of 9 − bit programmable capacitor arrays (PCAs) are implemented in a low-cost 0.35µm CMOS process. Measured data is compared to mismatch of large PIP capacitors, theoretical models, and recently published data. Measurement results indicate an estimated average relative standard deviation of 0.43% for the 2f F unit capacitor, which is better than the reported mismatch of metal-oxide-metal (MOM) fringing capacitors implemented in an advanced 32nm CMOS process.
doi:10.1109/tcsii.2015.2468919 fatcat:yp7uwb2darb5bftzhro72zbgdy