Recent advances in microwave active filter design. Part 2: Tunable structures and frequency control techniques
This two-part paper presents a representative sample of recent advances in microwave active filter design. In the second part, we discuss design techniques for tunable structures and frequency control. First, we present switchable and continuously-tunable bandstop filters employing MMIC negative resistances to compensate for losses. Next, we detail several approaches to the design of tunable high-order "recursive-like" filters. Layouts and measurements are given for different MMIC implementations, with simulated results presented in other instances. Finally, we discuss new technologies and processes for future low-cost, low-noise microwave MMIC active functions. The article concludes with the description of a development, including experimental results, of frequency-control techniques based on locked-loop architectures. (C) 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 177-189, 2002.
microwave active filters frequency control fdnr active inductance recursive filters noise-wave formalism tunable filters