Low Power and Low Phase Noise Voltage-Controlled Oscillator and Frequency Synthesizer for Ultra-Low Power Transmitter

Abstract

This thesis presents two works for WSN/IoT applications The first one is a low power transmitter implemented with a voltage-controlled oscillator (VCO) and a Class-D power amplifier (PA) The gm-enhancement and current-reuse techniques are employed to improve the power efficiency of Colpitts VCO 8 times To suppress the frequency pulling effect and frequency modulation of the LO signal by magnetic coupling of the inductor the proposed Colpitts VCO is implemented using the clover-shaped (4-lobed) inductor Implemented in 180 nm CMOS process the low power VCO operating frequency is 2 4 GHz and the phase noise is -123 1 dBc/Hz at a 1 MHz offset while consuming 2 76 mW from a 1 2 V supply voltage The second work is a fractional-N frequency synthesizer for ultra-low power transmitter applications implemented in 90 nm CMOS process The fractional-N frequency employs an injection-locked ring oscillator (ILRO) and delta-sigma phase rotator (?? PR) In order to synthesize different frequencies the ??PR is applied to perform phase randomization and rotation around the multi-phase outputs of ILRO The frequency synthesizer is capable of generating frequencies from 42 35 to 45 MHz that can support the frequency channel of our proposed ultra-low power transmitter in ISM bands The frequency synthesizer is also suitable for frequency shift keys (FSK) modulation in the transmitter since its output frequency can be generated by applying the FSK data to modulate the ??PR The phase noise is -120 dBc/Hz at a 1MHz offset while consuming 254 μW from a 0 7 V supply voltage Keywords: Ultra-low power transmitter voltage-controlled oscillator clover-shaped (4-lobed) inductor frequency synthesizer injection-locked delta-sigma phase rotator *Author **Advisor

Date of Award	2020
Original language	English
Supervisor	Kuang-Wei Cheng (Supervisor)