Noise Analysis of Radio Frequency Circuits

In high speed communications and signal processing applications, random electrical noise that emanates from devices has a direct impact on critical high level specifications, for instance, system bit error rate or signal to noise ratio. Hence, predicting noise in RF systems at the design stage is extremely important. Additionally, with the growing complexity of modern RF systems, a flat transistor-level noise analysis for the entire system is becoming increasingly difficult. Hence accurate modelling at the component level and behavioural level simulation techniques are also becoming increasingly important. In this book, we concentrate on developing noise simulation techniques for RF circuits. The difference between our approach of performing noise analysis for RF circuits and the traditional techniques is that we first concentrate on the noise analysis for oscillators instead of non-oscillatory circuits. As a first step, we develop a new quantitative description of the dynamics of stable nonlinear oscillators in presence of deterministic perturbations. Unlike previous such attempts, this description is not limited to two-dimensional system of equations and does not make any assumptions about the type of nonlinearity. By considering stochastic perturbations in a stochastic differential calculus setting, we obtain a correct mathematical characterization of the noisy oscillator output. We present efficient numerical techniques both in time domain and in frequency domain for computing the phase noise of oscillators. This approach also determines the relative contribution of the device noise sources to phase noise, which is very useful for oscillator design. This new way of characterizing the oscillator output has a far-reaching impact on the noise analysis methodology for nonautonomous circuits, which we also investigate. We also use the perturbation analysis results of oscillators to derive the phase noise of phase feedback systems such as phase-locked loops. We formulate the problem as a stochastic differential equation and is solved in presence of circuit white noise sources yielding the spectrum of the PLI output. Noise Analysis of Radio Frequency Circuits is written for circuit designers and will be of particular interest to RF circuit designers.