Analysis and Design of CMOS Active Dual-Mode Ring-Resonator Filters

本論文之主題，乃分析以環形諧振器為主體之雙模濾波器電路，整合主動電路，設計於K頻段，並實現於零點一三微米互補式金氧半導體中。本文所提出之雙模環形諧振器，由一準橫向電磁模互補式金屬環狀傳輸線，連接並聯之金屬-絕緣體-金屬電容作為微擾元件而構成。在此，兩個交錯耦合對垂直放置，作為主動補償電路，與環形諧振器作對稱之聯結整合，可顯著提升諧振器之品質因子，亦可觀地諧振器之尺寸。本論文將探討雙模濾波器之基本特性，包含不考慮負載效應之諧振頻率、傳輸零點、耦合係數等等。此外，在討論主動補償與品質因子增進機制的同時，線性度、雜訊、功耗、溫度效應等等，皆為其伴隨的重要議題。並且，本文更專注探討不同的微擾模式，與不同的輸入/輸出埠之相對位置對於本雙模濾波器行為之影響。當輸入埠與輸出埠的距離不再是四分之一個等效波長時，或當微擾電容的位置改變時，更或，當存在一可變的信號源與負載之直接耦合元件時，濾波器的諧振頻率、傳輸零點等特性將如何隨之變化，本論文將根據以上各種狀況詳而分析之。基於此，本研究實現幾種不同微擾模式與不同輸入/輸出埠安排模式之雙模濾波器，包含有：對稱耦合、非對稱微擾耦合、非對稱負載耦合等模式。此幾種濾波器，除去直流偏壓電路與波源-負載耦合元件之面積，其雙模諧振器之尺寸皆為邊長270微米之正方形，且在每個雙模濾波器中，選用的交錯耦合對之電晶體尺寸及接線尺寸皆相同。此五型雙模濾波器具有類似的線性度、雜訊指數與功耗，然而其散射參數則迥異。本研究顯示，相同的微擾元件，接在不同的相對位置上，可以在頻率軸上提供兩個傳輸零點或者不提供任何傳輸零點。對於非對稱耦合型而言，即便沒有微擾電容存在，亦可在頻率軸上提供兩個傳輸零點，但可能有非互易性的問題。當電容性之波源-負載之耦合增加時，兩個傳輸零點將靠近。根據以上方法，本研究實現了頻寬為2.58 %、0 dB介入損耗，裙帶係數為1.87之帶通濾波器。當電感性之波源-負載之耦合存在時，該濾波器可設計為一帶止濾波器。本文提出之雙模結構與一通用的濾波器架構之等同性亦會在此討論。本論文即依循這些原理，對於設計窄頻、高選擇性、縮小化且省電之帶通/帶止濾波器，展示一系統化的設計方法，在高精準度的金氧半導體製程中實現。本研究提出的電路與其他已發表的單晶片濾波器與主動濾波器做比較，結果顯示本研究提出的電路，在電路面積、頻寬、頻帶選擇性、介入損耗及反射損耗等特性上，皆有相對良好的表現。This dissertation presents analysis and design methods of monolithic K-band ring resonator dual-mode active filter fabricated in standard 0.13 μm complementary metal-oxide-semiconductor (CMOS) technology. The dual-mode ring resonator comprises a quasi-TEM complementary-conductive-strip transmission-line (CCS TL) loop and a shunt metal-insulator-metal (MIM) perturbation capacitor. Two CMOS cross-coupled pairs as active compensation circuits are integrated with the ring resonator symmetrically, forming a robust approach, which both enhances the quality factor of dual modes and reduces the resonator size significantly. Basic characteristics of the filter are discussed, including the unloaded resonant frequencies, transmission zeros, coupling coefficients, Q-enhancement mechanism, linearity, noise and power consumption. Various perturbation schemes and input/output arrangements of the dual-mode resonator topology are also investigated in detail. Variations of resonance frequencies and transmission zeros are analyzed thoroughly under the following situations: the distance between input and output are not 1/4 propagating wavelength, the position of the perturbation capacitor changes, and capacitive or inductive source-load coupling elements exist. Types of ring resonator dual-mode active filters with various perturbation types and input/output arrangement are all implemented and compared, including symmetric type, asymmetric-perturbation-coupled (APC) type, and asymmetric-load-coupled (ALC) type. In implementation stage, for all these types, the areas of the dual-mode active resonators are all 270 by 270 μm2 (0.02 λ0 × 0.02 λ0) without source-load coupling elements, DC biasing circuits and pads, and the sizes of transistors are also the same. For these filters, with similar linearity, noise figure and power consumption characteristics, the great difference of S-parameters are noteworthy for discussion. An identical perturbation element can yield two transmission zeros for a bandpass filter or no transmission zeros depending on the position of the element. Asymmetric coupling prototypes provide two transmission zeros even when no perturbation capacitor added, with the cost of non-reciprocity. With enhanced capacitive source-load couplings, the two transmission zeros become closer, and from this a bandpass filter with 2.58 % fractional bandwidth, 0-dB insertion and skirt factor of 1.87 is implemented. With inductive source-load couplings, a bandstop filter can be implemented. The equivalence between the proposed dual-mode filter topology and the universal building block theory is also discussed, exhibiting a systematic method to design a narrowband, high selectivity, low-profile and low-power bandpass or bandstop active filters in CMOS with high accuracy. Compared with published monolithic dual-mode filters and active filters, the proposed filters are seen possessing small area, narrowband, small insertion loss, high return loss and small skirt factor