학술논문
Mismatch Driven Systematic Design Methodology for Transistor Based Active Resistors
Document Type
Conference
Source
2023 IEEE 66th International Midwest Symposium on Circuits and Systems (MWSCAS) Circuits and Systems (MWSCAS), 2023 IEEE 66th International Midwest Symposium on. :619-623 Aug, 2023
Subject
Language
ISSN
1558-3899
Abstract
A step-by-step methodology to design transistor based active resistor considering the variance of the desired resistance is proposed in this work. Two cases with static and dynamic biasing of the active resistor are examined to validate the methodology. The methodology yields smaller area, exhibits linearity in cases where passive resistors fail and enables calibration against process, voltage, temperature variations of integrated circuits, which becomes increasingly important for advanced technology process nodes. The superiority of the proposed method is demonstrated by evaluating the area overhead, the variance of the phase margin, and gain bandwidth of a two-stage operational amplifier within a low voltage bandgap reference and the linear tunable output of a low dropout voltage regulator (LDO). The comparison is performed where a conventional passive resistor and an active resistor is, respectively, used for RC compensation in the opamp and a resistor bank in the LDO. The active resistor is designed to exhibit the same resistance as well as the same standard deviation in Monte Carlo simulations compared to the passive resistor, by selecting the size (W, L) and the bias voltage of the transistor. The area required for a passive resistor of 50 KΩ is more than 18 x the area of the respective active resistor for the same nominal resistance and exhibits improved standard deviation as demonstrated by simulation results for an industrial 65 nm technology process.