| dc.description.abstract | The thesis investigates the analysis, design and implementation of RF-end circuits for wireless transceiver with silicon-based process, such as low-noise amplifier, mixer, and voltage-controlled-oscillator, and some modeling of passive elements that needed in the circuits, such as inductor, transformer and pad. In passive elements like inductors, we study a series of researches and analysis to get higher quality factor with tsmc 0.35-μm process. UMC and tsmc 0.18-μm CMOS processes are adopted to implement the RF integrated circuits (RFICs). We also build inductor library and use them to design C-band VCOs. The thesis is divided into 6 chapters. According to different circuit design approach, the design and measurement are discussed in detail in each chapter.
The challenges in the RFIC design are introduced in Chapter 1. The passive elements, such as inductors, transformers, microstrip-line and pad are discussed in Chapter 2. The most important parameters of inductor are the resonant frequency, quality factor Q and occupied area. Several methods to enhance quality factor are also discussed, which include symmetrical-differential inductor, pattern-ground-shield inductor and deep-trench-mesh inductors. Furthermore, a compact 3-D stacked inductor is also introduced. In pattern-ground-shield inductor, there are four materials as shielding. They are Nwell, Poly, (N+ diffusion) and metal layers, respectively. From experimental data, the poly layer for PGS obtains the best performance.
The low noise amplifier and wideband amplifier design are presented in Chapter 3. Some circuit architectures for LNA and wideband techniques are also described. The physical structure and the figure of merit of transistor such as cut-off frequency ft, maximum oscillation frequency fmax, maximum available gain Gmax and noise sources are introduced. A wideband amplifier can be applied for the high data rate transmission. The techniques for the wideband amplifier, such as shunt-peaking, ft doubler and distributed structure, are explored. After then, two wideband amplifiers named A and B circuits are implemented by tsmc and UMC CMOS processes, respectively. A circuit obtains a 6-GHz bandwidth of 12~13dB gain with 1-dB gain-flatness. The input/output return losses are better than 10dB. The achieved noise figure is better than 6 dB. The measured input P1dB of -16dBm and input IP3 is -5dBm. B circuit obtains a 7-GHz bandwidth of 8~9dB in gain with 1-dB gain-flatness. The measured input/output return losses are better than 8dB. The achieved noise figure is better than 5dB. The measured input P1dB is -7dBm and input IP3 is 1dBm.
The mixer design is explored in Chapter 4. Various circuit architectures for mixer, such as single-sideband, image-reject, multi-gated, transformer-coupled and sub-harmonic mixers are introduced here. The important parameters of mixer, such as conversion gain, linearity, port-to-port isolations are also introduced. Two special mixers are proposed to enhance their linearity. The first circuit is a modified Gilbert-cell mixer which uses PMOS to replace NMOS as a transconductance amplifier. The other mixer is implemented with multi-gated structure. The transconductance gm can be linearized to reduce non-linearity effect. In order to operate at low voltage supply, a folded-current mixer with transformer-coupled is implemented. The modified Gilbert-cell mixer achieves a conversion gain of -0.3dB, input P1dB of -2dBm, input IP3 of 6dBm at 2.4GHz. The port-to-port isolations are better than 20dB. The multi-gated mixer achieves a conversion gain of -6.5dB, input P1dB of -1dBm, input IP3 of 8dBm at 1.2GHz. The port-to-port isolations are better than 30dB. The transformer-coupled mixer achieves a conversion gain of -1.6dB, input P1dB of -3dBm and input IP3 of 3dBm at 5.8GHz. The port-to-port isolations are better than 40dB.
Voltage-controlled-oscillator (VCO) design is presented in Chapter 5. The parameters of VCO and low phase noise design are firstly introduced. A designed 10GHz VCO achieves a turning range of 200MHz, output power of -3.5dBm, and phase noise about -106dBc at 1MHz offset frequency. Based on our built inductor, two VCOs with singled-ended and differential-driven inductors are designed for comparison. The VCO with differential-driven inductor achieves the better phase noise performance. Not only by theory but also by measured data have shown, the figure of merit (FOM) of the VCO with differential-driven inductor accomplishes 8 higher than that of with single-ended inductor. The VCO with single-ended inductor achieves a turning range of 320MHz, output power of -4.5dBm and phase noise about -102dB/Hz at 1MHz offset frequency. The VCO with differential-driven inductor achieved a turning range 210MHz, output power of -6.8dBm and phase noise about -112dB/Hz at 1MHz offset frequency. | en_US |