1Analog Signal Processing

Abstract—Analog signal processing (ASP) is presented as a systematic approach to address future challenges in high speed and high frequency microwave applications. The general concept of ASP is explained with the help of examples emphasizing basic ASP effects, such as time spreading and compression, chirping and frequency discrimination. Phasers, which repre-sent the core of ASP systems, are explained to be elements exhibiting a frequency-dependent group delay response, and hence a nonlinear phase response versus frequency, and various phaser technologies are discussed and compared. Real-time Fourier transformation (RTFT) is derived as one of the most fundamental ASP operations. Upon this basis, the specifications of a phaser – resolution, absolute bandwidth and magnitude balance – are established, and techniques are proposed to enhance phasers for higher ASP performance. Novel closed-form synthesis techniques, applicable to all-pass transmission-type cascaded C-section phasers, all-pass reflection-type coupled resonator phasers and band-pass cross-coupled resonator phasers are described. Several applications using these phasers are presented, including a tunable pulse delay system, a spectrum sniffer and a real-time spectrum analyzer (RTSA). Finally, future challenges and opportunities are discussed. Index Terms—Analog signal processing (ASP), phaser, frequency-dependent group delay, dispersion engineering, dis-persive delay structure, chirping, real-time Fourier transform, C-section and D-section, cross-coupled resonators, filter synthesis. I