一具有高輸出頻率範圍應用於連續頻率調變波雷達之三階頻率合成器

Abstract

本篇論文提出一個5 GHz頻率調變連續波(Frequency-Modulated Con-tinuous Wave)訊號產生器。所提出之電路主要目標為在低中心頻率時產生更大的頻率調變範圍(Modulation Range)，如此能在相同調變範圍下大幅降低功耗。採用以小數型鎖相迴路(Fractional-N Phase-locked Loop)為主的頻率合成器作為訊號產生器，此頻率合成器能以5 GHz為中心頻率調變700MHz(13.6%)的頻率範圍。一可變換極性之三階鎖相迴路(Type-3 PLL)被應用在本架構中，可有效改善在頻率轉折點和頻帶切換點的線性度。除此之外三階的架構亦可打破迴路頻寬對調變速度的限制。本論文提出透過切換頻帶控制電路(Switching Band Control circuit)和多組可變電容之LC壓控振盪器(Multi-varactor LC Voltage Control Oscillator)的組合來有效地提高輸出頻率的調變範圍，使頻率調變連續波雷達在距離的量測上能達到更高的準確度。本架構以台積電四十奈米互補式金氧半製程實現，所提出的頻率調變連續波訊號產生器總面積為1.96平方毫米而功耗則為3.2毫瓦。在鎖相迴路模式以5GHz為中心頻率，在相對於主頻率1 MHz的位置下所量測到的相位雜訊為-110 dBc/Hz。在頻率調變連續波模式以2.3 ms為週期調變700MHz的頻率下量測到的頻率誤差方均根值為625 kHz。

This thesis presents a 5-GHz frequency-modulated continuous wave sig-nal generator(FMCW). The presented circuit aims to generate a wider fre-quency modulation range at low center frequency that grants significant ad-vantage at saving power. Utilizing a fractional-N phase-locked loop (PLL)-based synthesizer as the FMCW generator, the synthesizer modulates thecarrier frequency across a range of 700 MHz(13.6%). A Type-3 architec-ture with a switchable polarity is embedded to improve the linearity aroundthe chirp turning-around points (TAPs) and switching-bands points (SAPs).Moreover, Type-3 architecture break the trade-off between modulation slopeand PLL loop bandwidth. Switching Band Control (SBC) circuit and Multi-varactorLCVoltageControlOscillator(MV-VCO)areproposedasaefficientmethod to increase the modulation range so that the FMCW signal generatorcan achieve high resolution in distance detecting.FabricatedinTSMC40-nm1P10MCMOStechnology, theproposedsig-nal generator consume 3.2 mW power and occupies1.96mm2die area. Themeasured phase noise from 5 GHz carrier is -110 dBc/Hz at 1 MHz offset.Themeasuredroot-mean-square(rms)frequencyerrorofthegeneratedtrian-gle chirp over 1.15 ms period is 625 kHz.