A Low Power Low Phase Noise Oscillator for MICS Transceivers

Abstract

A low-power, low-phase-noise quadrature oscillator for Medical Implantable Communications Service (MICS) transceivers is presented. The proposed quadrature oscillator generates 349~689 MHz I/Q (In-phase and Quadrature) signals covering the MICS band. The oscillator is based on a differential pair with positive feedback. Each delay cell consists of a few transistors enabling lower voltage operation. Since the oscillator is very sensitive to disturbances in the supply voltage and ground, a self-bias circuit for isolating the voltage disturbance is proposed to achieve bias voltages which can track the disturbances from the supply and ground. The oscillation frequency, which is controlled by the bias voltages, is less sensitive to the supply and ground noise, and a low phase noise is achieved. The chip is fabricated in the UMC (United Microelectronics Corporation) 0.18 μm CMOS (Complementary Metal Oxide Semiconductor) process; the core just occupies a 28.5 × 22 μm2 area. The measured phase noise is −108.45 dBc/Hz at a 1 MHz offset with a center frequency of 540 MHz. The gain of the oscillator is 0.309 MHz/mV with a control voltage from 0 V to 1.1 V. The circuit can work with a supply voltage as low as 1.2 V and the power consumption is only 0.46 mW at a 1.8 V supply voltage.

A Novel Dual-Band Six-Phase Voltage-Control Oscillator

“…These sensor devices help the IoT systems collect large amounts of data. Therefore, these sensor devices are the basic devices used in big data research [ 1 , 2 , 3 , 4 , 5 ]. However, these devices require low power circuits to extend device life time.…”

“…Small size and low cost make the device more popular, and good circuit characteristics to improve the performance of the device. For example, a low power low phase noise differential ring oscillator can effectively increase the use time of the Medical Implantable Communications Service (MICS) transceivers [ 3 ]. The integration of analog-to-digital converter, voltage-controlled oscillator, receiver, transmitter and digital circuits on a single chip reduces the size and cost of the sensor system [ 4 ].…”

“…Figure 1 shows the block diagram of Medical Implantable Communications Service (MICS) transceivers. Obviously, whether it is the reference clock circuit [ 6 , 11 ] or local oscillator circuit [ 3 , 4 , 12 ], the VCO is an indispensable component in sensor devices. Therefore, the characteristics of the VCO affect the performance of the sensor products [ 6 , 11 , 13 ].…”

“…Most of the reference clock circuit and part of the local oscillator circuit are implemented with a ring structure [ 1 , 13 , 14 ]. These VCOs are implemented by single-ended delay cells or differential delay cells [ 1 , 3 ]. A single-ended delay cell provides a larger output swing, a smaller chip area, a lower dissipated current, and a less complex design than a differential delay cell [ 3 , 8 , 15 , 16 ].…”

“…These VCOs are implemented by single-ended delay cells or differential delay cells [ 1 , 3 ]. A single-ended delay cell provides a larger output swing, a smaller chip area, a lower dissipated current, and a less complex design than a differential delay cell [ 3 , 8 , 15 , 16 ]. However, VCOs that are based on single-ended delay cells cannot provide even-phase outputs.…”