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

A Supply Voltage and Temperature Variation-Tolerant Relaxation Oscillator for Biomedical Systems Based on Dynamic Threshold and Switched Resistors A fully integrated supply voltage and temperature variation-tolerant relaxation oscillator for biomedicalsystems 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-μm 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/°C as temperature varied from -30 °C to 120 °C 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 mm².