A Supply Voltage and Temperature Variation-Tolerant Relaxation Oscillator for Biomedical Systems Based on Dynamic Threshold and Switched Resistors

摘要

A fully integrated supply voltage and temperature variation-tolerant relaxation oscillator for biomedical systems has been presented. Concepts of dynamic threshold and switched resistors are proposed to improve the frequency stability against power supply and temperature variations, respectively. This design was verified in a 0.35- standard CMOS process with a 3 V supply. Measurement results show the frequency drift of 0.6% from 2.4 to 4.0 V and temperature stability of 53.9 ppm/ as temperature varied from to 120 at a typical working frequency of 4 MHz. With the consideration of resistor and transistor matching, the oscillator was implemented in a core area of 0.05 .