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International Journal of Engineering & Technology Sciences
IJETS 2015, 3(1), 45-54
A Temperature Compensated CMOS Differential Ring Oscillator with Low Power Consumption for RFID Applications
a Department of Electrical and Electronics Engineering Shiraz University of Technology, Shiraz, Iran
ABSTRACT
This paper presents the three-delay-stage low power differential ring oscillator used for RFID applications. To make oscillator frequency independent from temperature, two temperature compensation methods have been used. In the first method the NMOS diode-connected transistor is connected in series with PMOS load. As a result of complementary behavior of NMOS and PMOS, the temperature variation of the output voltage is reduced at each stage. In the second method in order to decrease the dependence of oscillator current to temperature, a diode-connected transistor has been used in the current supply. The simulation is done by cadence software in 0.18 μm CMOS technology, and the power consumption of oscillator is 502 nW. At the central frequency of 7 MHz, the frequency deviation within the temperature range of -10 to 150°C is equal to 267 ppm/°C. Also the phase noise of the oscillator at the offset frequency of 100 KHz is -80.2 dBc/Hz, and the jitter period for 10000 cycles is 0.94 ns (rms).