Digitally-Assisted Design, Simulation and Testing Techniques for Optimization of Analog/RF Integrated Circuits

High-performance low-cost radio frequency (RF) transceivers are essential in today's wireless systems. Contemporary manufacturing process technologies and device scaling have helped the integration of analog and RF circuits with high performance, but often with high sensitivity to increasing process variations when chips are fabricated in high volumes. This trend has motivated designers to incorporate more digital circuits for performance optimizations of analog/RF circuits. A repercussion of adding on-chip circuits is the rise of design and verification complexity of RF devices, which is paralleled by demands for shorter design cycles and better reliability. These challenges create the need for improved simulation and testing methodologies.;This dissertation focuses on the design and integration of digital circuits with analog/RF circuits for performance optimizations. Spectral analysis for the evaluation of analog/RF circuits is a standard procedure for which the fast Fourier transform (FFT) algorithm is widely used. However, the majority of existing FFT implementations on chips consume excessive area and power for built-in testing applications. In this research, an FFT-based performance monitoring technique with multi-tone test signals has been created for efficient on-chip spectral analysis of analog/RF circuits. This method enables to estimate third-order intermodulation components of up to 50 dB below the fundamental tones with an accuracy of +/-1.5 dB based on the output spectrum of analog circuits. The capability of this technique to accurately determine the power of two test tones as well as their distortion components and intermodulation products was demonstrated by designing an on-chip linearity calibration scheme for a tunable low-noise amplifier.;A key aspect of practical circuit and system design is to ensure high performance with high reliability and low cost. Therefore, it is advantageous to utilize test and simulation methods for simultaneous optimization of a design under test and a performance enhancement technique (e.g., self-calibration circuits and linearization methods) prior to fabrication of chips or systems. In this research, a simulation approach to concurrently design and optimize an entire system at a desired abstraction level was developed for integrated amplifiers. The design and optimization of a 10 W inverted Doherty power amplifier (PA) with a digital predistortion (DPD) linearization technique was completed to exemplify the effectiveness of the simulation platform. In addition, an integrated hardware-software co-design approach that allows DPD tuning to meet specification requirements with minimum resources was developed together with industrial collaborators. Tuning of the DPD technique was performed with several off-the-shelf power amplifiers for performance optimization of the integrated PA-DPD system. Furthermore, a tuning method was developed that incorporates a digital-to-analog converter in the integrated PA-DPD system. With this approach, the error signal generated by the digital predistortion technique can be utilized to automatically tune a bias voltage in the power amplifier for optimal performance. Simulation results from a closed-loop system consisting of an inverted Doherty power amplifier with digital predistortion were evaluated to validate the tuning mechanism.