使用標準矽製程整合90°和180°分合波器之吉伯特微混頻器

Abstract

In this dissertation, all single-ended Gilbert micromixers are demonstrated using 0.35-?m SiGe BiCMOS technology. For wideband operation, a transimpedance amplifier with resistive feedback is utilized in the IF stage while a broadband balun or a rat-race coupler is employed to generate wideband differential local oscillator (LO) signals. These microwave passive components in our study can generate truly balanced signals even in the presence of a lossy low-resistivity (~10 Ω•cm) silicon substrate. A systematic approach to measure the frequency response of each individual stage in a Gilbert mixer is developed in Chapter 2. In Chapter 3, adjustable and reactive in-phase/quadrature (I/Q) generators with constant resistance are proposed with the properties of low loss, dual-band implementation, and high quadrature accuracy. The quadrature phase property and input matching of the I/Q generator can be achieved at all frequencies simultaneously. However, the magnitude balance of the dual-band I/Q generator is achieved at two designed frequencies. A 2.4/5.2 GHz I/Q down-converter and a 2.4/5.7 GHz single-sideband up-converter are demonstrated. In Chapter 4, this dissertation realized a broadband uniplanar phase-inverter rat-race coupler using a standard silicon process, and then analyzed this coupler under a lossy condition. A phase inverter is employed in this coupler, not only to extend the operation bandwidth, but also to generate balanced outputs, while symmetrical spiral-shaped coplanar striplines (CPSs) are also utilized to shrink the coupler size, as well as to construct a phase inverter in the middle of one of spiral CPSs. The distortionless lossy CPS has a real characteristic impedance, and thus, perfect port matching of the coupler can be achieved. A wideband Gilbert micromixer with an LO rat-race coupler is demonstrated and works from 2.5 to 13 GHz. In Chapter 5, the wideband mixer with an integrated LO Marchand balun has the conversion gain of 15 dB and works from 3.5 to 14.5 GHz. In addition, a 15.5-dB conversion gain Gilbert mixer with a miniaturized lumped-element Marchand balun is demonstrated for UWB applications. In Chapter 6, a planar Marchand balun and its modification are analyzed and designed with a coupling factor and a corresponding characteristic impedance. The modification has duality with the original Marchand balun in structure. However, this proposed alteration has a much larger operation bandwidth than the prototype. Additionally, based on our analysis, the fact is found that the balun’s outputs are always equal in magnitude and opposite in phase within all frequency ranges, as long as the material is homogeneous. Namely, these baluns, even in a lossy material, still function well. The implemented modified Marchand balun has a better performance with outputs of an 180±5? phase difference and a ±0.5-dB magnitude imbalance from 4 to 25 GHz. The fractional bandwidth is more than 140%. Also, the modified Marchand balun integrated at the LO stage of the mixer offers more than 30%-operation bandwidth.