Li Dawei, Liu Dongsheng, Kang Chaojian, Zou Xuecheng
School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430000, China.
Sensors (Basel). 2017 Jan 12;17(1):140. doi: 10.3390/s17010140.
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.
本文介绍了一种用于医疗植入通信服务（MICS）收发器的低功耗、低相位噪声正交振荡器。所提出的正交振荡器可产生覆盖MICS频段的349~689 MHz同相/正交（I/Q）信号。该振荡器基于具有正反馈的差分对。每个延迟单元由几个晶体管组成，可实现更低电压工作。由于该振荡器对电源电压和地的干扰非常敏感，因此提出了一种用于隔离电压干扰的自偏置电路，以获得能够跟踪电源和地干扰的偏置电压。由偏置电压控制的振荡频率对电源和地噪声不太敏感，从而实现了低相位噪声。该芯片采用联华电子（UMC）0.18μm互补金属氧化物半导体（CMOS）工艺制造；核心部分仅占28.5×22μm²的面积。在中心频率为540 MHz、1 MHz频偏时，测得的相位噪声为-108.45 dBc/Hz。振荡器在0 V至1.1 V的控制电压下增益为0.309 MHz/mV。该电路可在低至1.2 V的电源电压下工作，在1.8 V电源电压下功耗仅为0.46 mW。
