Analysis and design of wideband voltage controlled oscillators using self-oscillating active inductors.

Voltage controlled oscillators (VCOs) are essential components of RF circuits used in transmitters and receivers as sources of carrier waves with variable frequencies. This, together with a rapid development of microelectronic circuits, led to an extensive research on integrated implementations of the oscillator circuits. One of the known approaches to oscillator design employs resonators with active inductors electronic circuits simulating the behavior of passive inductors using only transistors and capacitors. Such resonators occupy only a fraction of the silicon area necessary for a passive inductor, and thus allow to use chip area more eectively. The downsides of the active inductor approach include: power consumption and noise introduced by transistors. This thesis presents a new approach to active inductor oscillator design using selfoscillating active inductor circuits. The instability necessary to start oscillations is provided by the use of a passive RC network rather than a power consuming external circuit employed in the standard oscillator approach. As a result, total power consumption of the oscillator is improved. Although, some of the active inductors with RC circuits has been reported in the literature, there has been no attempt to utilise this technique in wideband voltage controlled oscillator design. For this reason, the dissertation presents a thorough investigation of self-oscillating active inductor circuits, providing a new set of design rules and related trade-os. This includes: a complete small signal model of the oscillator, sensitivity analysis, large signal behavior of the circuit and phase noise model. The presented theory is conrmed by extensive simulations of wideband CMOS VCO circuit for various temperatures and process variations. The obtained results prove that active inductor oscillator performance is obtained without the use of standard active compensation circuits. Finally, the concept of self-oscillating active inductor has been employed to simple and fast OOK (On-Off Keying) transmitter showing energy eciency comparable to the state of the art implementations reported in the literature

High performance RF and baseband building blocks for wireless receivers

Because of the unique architecture of wireless receivers, a designer must understand both the high frequency aspects as well as the low-frequency analog considerations for different building blocks of the receiver. The primary goal of this research work is to explore techniques for implementing high performance RF and baseband building blocks for wireless applications. Several novel techniques to improve the performance of analog building blocks are presented. An enhanced technique to couple two LC resonators is presented which does not degrade the loaded quality factor of the resonators which results in an increased dynamic range. A novel technique to automatically tune the quality factor of LC resonators is presented. The proposed scheme is stable and fast and allows programming both the quality factor and amplitude response of the LC filter. To keep the oscillation amplitude of LC VCOs constant and thus achieving a minimum phase noise and a reliable startup, a stable amplitude control loop is presented. The proposed scheme has been also used in a master-slave quality factor tuning of LC filters. An efficient and low-cost architecture for a 3.1GHz-10.6GHz ultra-wide band frequency synthesizer is presented. The proposed scheme is capable of generating 14A novel pseudo-differential transconductance amplifier is presented. The proposed scheme takes advantage of the second-order harmonic available at the output current of pseudo-differential structure to cancel the third-order harmonic distortion. A novel nonlinear function is proposed which inherently removes the third and the fifth order harmonics at its output signal. The proposed nonlinear block is used in a bandpass-based oscillator to generate a highly linear sinusoidal output. Finally, a linearized BiCMOS transconductance amplifier is presented. This transconductance is used to build a third-order linear phase low pass filter with a cut-off frequency of 264MHz for an ultra-wide band receiver. carrier frequencies

Passive and active circuits in cmos technology for rf, microwave and millimeter wave applications

The permeation of CMOS technology to radio frequencies and beyond has fuelled an urgent need for a diverse array of passive and active circuits that address the challenges of rapidly emerging wireless applications. While traditional analog based design approaches satisfy some applications, the stringent requirements of newly emerging applications cannot necessarily be addressed by existing design ideas and compel designers to pursue alternatives. One such alternative, an amalgamation of microwave and analog design techniques, is pursued in this work. A number of passive and active circuits have been designed using a combination of microwave and analog design techniques. For passives, the most crucial challenge to their CMOS implementation is identified as their large dimensions that are not compatible with CMOS technology. To address this issue, several design techniques – including multi-layered design and slow wave structures – are proposed and demonstrated through experimental results after being suitably tailored for CMOS technology. A number of novel passive structures - including a compact 10 GHz hairpin resonator, a broadband, low loss 25-35 GHz Lange coupler, a 25-35 GHz thin film microstrip (TFMS) ring hybrid, an array of 0.8 nH and 0.4 nH multi-layered high self resonant frequency (SRF) inductors are proposed, designed and experimentally verified. A number of active circuits are also designed and notable experimental results are presented. These include 3-10 GHz and DC-20 GHz distributed low noise amplifiers (LNA), a dual wideband Low noise amplifier and 15 GHz distributed voltage controlled oscillators (DVCO). Distributed amplifiers are identified as particularly effective in the development of wideband receiver front end sub-systems due to their gain flatness, excellent matching and high linearity. The most important challenge to the implementation of distributed amplifiers in CMOS RFICs is identified as the issue of their miniaturization. This problem is solved by using integrated multi-layered inductors instead of transmission lines to achieve over 90% size compression compared to earlier CMOS implementations. Finally, a dual wideband receiver front end sub-system is designed employing the miniaturized distributed amplifier with resonant loads and integrated with a double balanced Gilbert cell mixer to perform dual band operation. The receiver front end measured results show 15 dB conversion gain, and a 1-dB compression point of -4.1 dBm in the centre of band 1 (from 3.1 to 5.0 GHz) and -5.2 dBm in the centre of band 2 (from 5.8 to 8 GHz) with input return loss less than 10 dB throughout the two bands of operation

RF CMOS Oscillators for Modern Wireless Applications

While mobile phones enjoy the largest production volume ever of any consumer electronics products, the demands they place on radio-frequency (RF) transceivers are particularly aggressive, especially on integration with digital processors, low area, low power consumption, while being robust against process-voltage-temperature variations. Since mobile terminals inherently operate on batteries, their power budget is severely constrained. To keep up with the ever increasing data-rate, an ever-decreasing power per bit is required to maintain the battery lifetime. The RF oscillator is the second most power-hungry block of a wireless radio (after power amplifiers). Consequently, any power reduction in an RF oscillator will greatly benefit the overall power efficiency of the cellular transceiver. Moreover, the RF oscillators' purity limits the transceiver performance. The oscillator's phase noise results in power leakage into adjacent channels in a transmit mode and reciprocal mixing in a receive mode. On the other hand, the multi-standard and multi-band transceivers that are now trending demand wide tuning range oscillators. However, broadening the oscillator’s tuning range is usually at the expense of die area (cost) or phase noise. The main goal of this book is to bring forth the exciting and innovative RF oscillator structures that demonstrate better phase noise performance, lower cost, and higher power efficiency than currently achievable. Technical topics discussed in RF CMOS Oscillators for Modern Wireless Applications include: Design and analysis of low phase-noise class-F oscillators Analyze a technique to reduce 1/f noise up-conversion in the oscillators Design and analysis of low power/low voltage oscillators Wide tuning range oscillators Reliability study of RF oscillators in nanoscale CMO