An Active Resistor With a Lower Sensitivity to Process Variations, and its Application in Current Reference

Abstract

A novel active resistor circuit offering less sensitivity to process and temperature variations without any extra trimming is proposed. The circuit consists of two accurately matched, high resistance polysilicon (hripoly) resistors and a voltage-controlled MOS resistor, and it is designed for the industrial temperature range (-20 • C to 85 • C) in the TSMC 180 nm general-purpose process. The actual performance of the circuit is analyzed by using the Corner and Monte Carlo analyses that comprise two thousand samples for the global and local process variations. The maximum error in the resistor value is ±6.2 %, with the standard deviation of σ = 1.2 %. The proposed active resistor reduces the maximum error from ±15 % to ±6.2 % when the both the process and the temperature variations are considered without trimming. As an application, a transconductor and a current reference based on the novel active resistor are introduced, and their accuracy-related performance is studied.

A High-Accuracy RC Time Constant Auto-Tuning Scheme for Integrated Continuous-Time Filters

“…Consequently, the ratio k between the resistors is not sensitive to PVT variations. Equation (7) indicates that R 1 C BANK can be tuned into a fixed target value determined by k and T. The resultant control word is latched to control the capacitor bank in slave circuits.…”

“…However, in complementary metal-oxide semiconductor (CMOS) technologies, the absolute value of resistance and capacitance is greatly affected by process and temperature. As a result, RC time constant uncertainty of up to 50% could occur due to variations in process, voltage, and temperature (PVT); this uncertainty will reduce the frequency performance of filters, leading to reliability issues in integrated circuits [ 5 , 6 , 7 , 8 , 9 , 10 ]. Accordingly, many real-time on-chip automatic tuning methods have been proposed and developed to improve the accuracy in the calibration of the RC time constant [ 2 , 6 , 11 , 12 , 13 , 14 , 15 ].…”