Computer aided design of broadband microwave diode detectors using filter approximations

Abstract

A new proposed computer aided method for the design of broadband microwave planar square law diode detectors is presented. In this method, a passive network is connected to the diode cathode, then this combination is modeled with an RLC load. Using the explicit formulas of filter approximations such as Butterworth and Chebyshev, a broadband matching network is synthesized between the RLC load and a resistive element which is not equal to the characteristic impedance. Then another matching network (filter) is synthesized between the resistive element and the characteristic impedance. This method produces diode detectors with low input VSWR over its useful broad bandwidth without using diode biasing (self bias) and without using resistance in the diode matching network. Examples of broadband square law Schottky barrier diode detectors with their analysis are presented to illustrate the design steps of the proposed method.