A TEMPERATURE VARIANT RELAXATION OSCILLATOR FOR BIOMEDICAL SYSTEMS
Author’s Name : Parthiban K G | Ramya P
Volume 04 Issue 02 Year 2017 ISSN No: 2349-252X Page no: 7-10
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 22nm standard CMOS process with 2 V supply. Measurement results show the frequency drift of 0.6% from 2V 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. The concepts of dynamic threshold (DT) and switched resistors (SRs) techniques are introduced to make the oscillator immune to voltage and temperature variations, respectively. These techniques minimize the frequency drift caused by supply variation as well as by temperature changes at the price of higher design complexity and larger chip area. The proposed SRs concept is aimed at making oscillation frequency insensitive to temperature in a process providing at least two types of resistors with different TCs.Index Terms Biomedical systems, clock generator, dynamic threshold (DT), frequency stability, relaxation oscillator, switched resistors (SRs).
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