應用於MB-OFDM UWB頻率合成器之鎖相迴路設計

Abstract

The frequency synthesizer is very important circuit of wireless communication system. To achieve different communication system standards, the frequency plan and specifications are also dissimilar. In this thesis a Phase Locked Loop (PLL) is designed for the Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) Ultra Wide Band (UWB) application. The PLL is operated at 6,336 MHz with 528 MHz reference input. The characteristics of this PLL are that it contains a Colpitts Voltage Control Oscillator (VCO) with transformer tank and a True Singe Phase Clock (TSPC) quadrature divide-by3 frequency divider. Besides, the power consumption of the PLL is low. To reduce chip area, the planar transformer is constructed by inter-wound metal conductors and consisted of two TSMC symmetric spiral inductors with turn ratio 1:1. A novel quadrature TSPC divide-by-3 circuit is proposed in this thesis. By using TSPC technology, the function of division-by-3 and 50% duty cycle quadrature outputs can be obtained for Single Side-Band (SSB) mixer use. The divide-by-3 adopted TSPC technique could generate 50% duty cycle quadrature outputs for single side-band SSB mixer. The maximum operation frequency of our designed quadrature TSPC divide-by-3 circuit is 2.5 GHz, while it is operated at 1,584 MHz in our application. The main advantages of this proposed divider are low circuit complex and low power consumption. The PLL design was fabricated in a TSMC 0.18m 1P6M CMOS process. The measured average phase noise of the PLL is -106 dBc/Hz at 1 MHz offset from the center frequency. The output power is -6 dBm and the jitter is 5.82 ps (p-p). The total chip area is 1.1 mm × 1.1 mm and the power consumption is 26 mW, excluding that of output buffers. The design work of band selectors (i.e., multiplexers) and Single Side-Band (SSB) mixers are demonstrated in the appendix. Two band selectors, one is a bi-way multiplexer for the frequency selection of 6,336 MHz or 3,168MHz and the other is a tri-way multiplexer for 1,320MHz, 792MHz, or 264MHz, are designed for the integration of MB-OFDM frequency synthesizer in the future. The total power consumption of these two selectors is 7.5 mW. Two SSB mixers are also designed for the integration of MB-OFDM frequency synthesizer, too. The types of SSB mixer output loads consist of resistive type and LC-resonant type. The output frequency of SSB mixer with resistive load is 2,640MHz and that of another SSB mixer with LC-tank load are 7,656 MHz, 7,128MHz, 6,600MHz, 4,488MHz, 3,960MHz and 3,432MHz。The total power consumption of these two SSB mixers is 15 mW。