載波調變頻率合成器之設計與分析暨平面化實現之15/30 GHz 震盪器/倍頻器

Abstract

本篇論文的第一部份,藉著對震盪器物理精確的了解而提出了一種嶄新的載波調變頻率合成技術.其中詳細的低相位雜訊設計考量乃藉由ISF來進行分析,這方法對雜訊的形成提供了一透徹的洞察,同時並能有效地指出每一個雜訊源對整體電路的影響.同時,為了探究電感的特性在震盪電路中扮演的角色,文中將探討三顆由不同電感構成之震盪器.其中量測結果在距2.83 GHz 載波600 kHz 處的相位雜訊為-106 dBc/Hz,與模擬所得之-107 dBc/Hz僅有1dB的差距.若將此單級的震盪器以四級環狀串接,則可得到擁有45o 相位差的輸出.此多相位震盪器的中心頻率為3.16 GHz,相位雜訊在距載波1 MHz處為-109.17 dBc/Hz.若以此多相位輸出的架構為核心,輔以相位切換電路的設計,可達成具快速切換特性的載波調變頻率合成器.其原理乃採用週期性的相位調變造成頻譜中心頻率的位移.本文展示了一個由台積電0.18微米製程製作的5 GHz載波調變頻率合成器.其功率消耗為46.5 mW,未鎖定時在距載波1MHz處之相位雜訊為-101.8 dBc/Hz.同時由取樣原理造成的突波可藉由主動式濾波器降至-40 dBc.此外,由於整個頻率的切換是在一開迴路中完成,因此切換的速度幾乎是立即性的.這象徵著在快速切換頻率合成器中的一個重大突破. 論文的第二部分將介紹一嶄新的毫米波訊號源電路設計,使用新式的高Q值平面波導共振腔.此一提出的共振腔乃是由平面印刷電路板以周圍切削,鍍銅製作而成.文中將此共振腔輔以創新的電路設計,達成一低相位雜訊的15 GHz微波震盪器.其最大輸出功率為14 dBm,相位雜訊距載波100 kHz處為–98 dBc/Hz.若與傳統的微帶線共振腔相比較,此新式平面波導共振腔能有效降低13 dBc的相位雜訊.此外,本文也設計了一15/30 GHz單級主動式倍頻器,其與15 GHz震盪器連結後的30 GHz毫米波訊號擁有9 dBm的輸出功率,相位雜訊距載波1MHz處為-102 dBc/Hz.此結果實現了一全平面式,以便宜的印刷電路技術達成的毫米波訊號源.

First part of this thesis presents the analysis and design of the carrier-modulated frequency synthesizer, based on physically understanding of the oscillator circuits. Detailed design considerations regarding low phase noise are exams through the ISF approach, which effectively provides a transparent insight into the noise contributions from each noise source. Three experimental LC oscillators fabricated by TSMC 0.25 um 1P5M foundry service are presented to investigate the effect of inductor Q on circuit performance. Measurements show a phase noise of –106 dBc/Hz at 600 kHz offset from 2.83 GHz carrier is achieved by using the PGS (Patterned Ground Shield) [24] inductor, while that simulated by ISF is –107 dBc/Hz. This success in noise prediction also paves the way for a better oscillator performance to accommodate stringent wireless standards. The LC oscillators can further be connected in a ring cascade to provide multi-phase output. In this work, we demonstrate a 4-stages LC oscillator that exhibits a 3.16 GHz, octant-phase output with measured phase noise of –109.17 dBc/Hz at 1MHz offset. Based on the multi-phase oscillator, the carrier modulated frequency synthesizer is designed and implemented using TSMC 0.18 um 1P6M process. Which incorporates the principle of periodic phase modulation on carrier; result in an open loop agile switching frequency synthesizer at 5 GHz. Measurements show the free-running 5GHz carrier with phase noise of –101.8 dBc/Hz at 1MHz offset, draws 18.6 mA from a 2.5V supply. Sidebands at integer multiples of the applied clock-rate can be ameliorated to –40 dBc through tracking active filter. The switching time is almost immediately attributes to the open-loop modulation, signifies an unprecedented evolution to fast-switching frequency synthesizer. Second part of this thesis presents an oscillator circuit topology that incorporates novel high-Q planar waveguide resonator. The proposed resonator is a waveguide cavity made in printed-circuit-board (PCB) process. Measurements show that the oscillator stabilized by the resonator delivers an output power of 14 dBm at 15 GHz and a phase noise of –98 dBc/Hz at 100 kHz offset from carrier, under 5 V single bias. Experimental results further indicate that the phase noise is degraded by 13 dB when the planar waveguide resonator is replaced by a conventional λ/4 microstrip resonator. Moreover, a single stage 15/30 GHz doubler is designed and driven by the oscillator, produces the 30 GHz output with power level of 9 dBm and phase noise of –102 dBc/Hz at 1MHz offset. Providing an alternative for establishing high-quality all-planar oscillators at millimeter-wave.