Effective Bandwidth Improvement Technique Based On Mismatch Analysis

The mismatch in cascaded two ports is a common cause of ripple increase and bandwidth reduction in broadband systems. A new mismatch factor, D, is defined to deal with the individual S 21 and global S 21 parameters in a cascaded network. The relationship between this D factor and the effective bandwidth is presented. This bandwidth can be improved inserting a matched attenuator. The method has been applied to a Q band broadband amplifier, based on two cascaded multistage MMIC amplifiers, used in a radiometer for a space application. Effective bandwidth has been improved inserting a series thin film resistor attenuator. The design expressions and criteria of such microstrip attenuators are described