Reseach On Multi-mode Multi-band Oscillator

High performance oscillator is always the research focus in RF front-end of wireless communication. With the number of standards in wireless communication gradually increasing, the corresponding modes and bands that terminals should support are more than ever. Broadband low-phase-noise and low-power oscillator have become an essential component in a versatile single chip. This thesis studied and designed three broadband low phase noise oscillator based on 130 nm CMOS process.1. A digitally controlled oscillator for GSM mobile applications has been designed. The control signals of frequency, bais, and noise filter are all digital. The improved second harmonic resonance structure achieves high impedance in the broad band. Ultimately, the oscillator covers 3.1-4.5 GHz and meets the requirements in frequency and phase noise with the GSM mobile station in all bands. Besides, thanks to the excellent performance of noise filtering, the normalized phase noise in the whole band is less than-165.4dBc/Hz@20MHz, and a ultra-low power consumption is kept below 7mW.2. Based on the linear time-vary model of phase noise, the harmonic oscillation’s impact on phase noise has been investigated and a resonator which has two resonances has been designed with a compact transformer. The improved drain waveform greatly reduces phase noise, making the normalized phase noise drops to less than-170dBc/Hz @20MHz.3. In this thesis, a broadband oscillator for the multi-band need of GSM/WCDMA transmitters has been designed. Also using the compact transformer, the oscillation frequency hopping occurs when the switch is opened or closed. The resulted high and low frequency bands cover 4.8-8.5 GHz with the relative bandwidth over 54%. An AMOS varactor is added to the improved switching circuit in the transformer’s secondary. The normalized phase noise of the oscillator in all bands is less than-162dBc/Hz@20MHz, meets the requirement of GSM/WCDMA transmitters.The performance of CMOS oscillator has been improved especially in phase noise and bandwidth. That makes the thesis can provide some useful references for the design and implementation of multi-mode multi-band oscillators.