The Research On Low-Power Frequency Source And Its Applications

Wireless communication has made people’s life more convenient, but current technology still cannot meet the people’s requirements. For example, high quality image, including HDTV, drives the IC towards high-speed and high-frequency; longer battery sustain time requires low-power IC. Also high-quality wireless communication need lower the noise in IC design. Therefore, the research hot topic of RF IC is low-power, high-speed and low-noise. Frequency sources are indispensable in RF transceivers and its performance determines the communication quality, so a high-performance frequency source is vital to RF transceivers. In conventional transceivers, frequency sources usually work only as carriers to transmit and receive data. However with the development of research work on injection locking technology, direct modulation on injection-lock-based frequency sources has been realized with high data rate and low power. This article focuses on the design of conventional frequency sources and applications based on injection locking technology. Simulation and measurement results are used to validate the above work.Voltage Control Oscillators (VCO) and Charge Pumps (CP) are important blocks in Charge Pump based Phase Lock Loop (CPPLL), which also can be named as Frequency Synthesizers (FS).As the essential blocks in CPPLL, a VCO with low-power, low-noise and wide tuning range is demanded and also challenging. In this thesis, several theories have been used to optimize the20GHz VCO (which is used in60GHz transceiver), and the measurement results show that15%tuning range and-98dBc@1MHz phase noise are achieved under4.8mW power consumption.Spurs of frequency synthesizers transfer noise into channels and deteriorate the Signal to Noise ratio (SNR), so the suppression to spurs is also important. The major contributions to spurs are from the current mismatch and nonlinearity of CP. This thesis focuses on the current mismatch and feed-through effect and proposes ways to alleviate the non-ideal effects. The feedback technique is used to adjust the reference current so as to widen the match range; Feed-forward capacitors are introduced to counteract the feed-through effect caused by the parasitic capacitors, and the simulation result shows the open speed of CP currents is faster.The extensive application of injection Locking technology in integrated circuits dates back to decades ago. Its excellent phase noise performance, easily frequency multiplication makes it more attractive in many applications. For sub-harmonic injection locking oscillators (ILO), harmonic spurs caused by the finite suppression ability of resonant network to un-wanted harmonics, are a big problem which leads to amplitude jitters in time domain. In this thesis, pulses with tunable duty cycle are injected into oscillators to suppress harmonic spurs, and the simulation results show the harmonic spurs are～40dB lower than the wanted harmonic.Another work based on injection locking technology in this article is the design of the lower-power high-speed QPSK/8PSK/16QAM transmitter, in which16QAM modulation is implemented first time based on LC injection locking technology. The simulation results show with small error vector magnitude (EVM),60Mbps data rate and an energy efficiency of0.12nJ/bit are achieved. This transmitter locates in industrial science and medical (ISM) band and targets to be used in disease diagnosis, like endoscopy capsule.