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 represent 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 Csection 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 realtime spectrum analyzer (RTSA). Finally, future challenges and opportunities are discussed.
