Design and Implementation of a Loss-Programmable Filtering Attenuator

Abstract

With the increased demand for modern wireless systems in various applications, the need for adaptable radio frequency (RF) systems has greatly increased. These modern systems rely on the ability to operate in the microwave frequency spectrum (1 GHz to 1 THz) without interference from other devices while also retaining the ability to detect very low and very high power signals simultaneously. There is also an ever-increasing demand for the reduction of cost, size, weight, and power (C-SWaP) of these modern RF systems that drives an ever-increasing demand for more agile filters in the microwave frequency spectrum. A filtering attenuator (filtenuator) is a device that combines the frequency-selective characteristics of a filter and the loss-programmable characteristics of an attenuator into a single component. In this thesis, a generalized theory of filtenuators is presented. A loss-programmable, third-order filtenuator is also designed to verify the generalized theory. The design of the filtenuator is based on tuning the resistance of a pi-network of resistors. The tuning of the resistances is achieved through the use of PIN diodes. The pi-network of resistances is built around a third-order filter that provides the filter response of the filtenuator. The filtenuator is designed to operate at 1 GHz and have a tunable attenuation range of 2-10 dB. This filtenuator demonstrates the feasibility of a tunable, low C-SWaP solution to increase RF system dynamic range as well as demonstrating a design process that allows for future development of filtenuators.