90 DEG phase shifter apparatus and method using a directly coupled path and a switched path

摘要

A method and apparatus for accomplishing a 90 DEG relative phase shift employing a high characteristic impedance outer leg of length lambda /2 and a low characteristic impedance through leg of length lambda /4. The high characteristic impedance outer leg is directly connected to the input and the output. The low characteristic impedance through leg is connected to the input and output with first and second diode paths. When the first and second diode paths are in the on state, the low characteristic impedance through leg receives a majority of the input power. Because of the impedance disparity between the high characteristic impedance outer leg and low characteristic impedance through leg, only a small amount of power is routed through the high characteristic impedance outer leg when the first and second diode paths are in the on state and the combined signal phase is not substantially effected. When the first and second diode paths are in the off state, the input signal is routed through the high characteristic impedance outer leg. Because the relative lengths of the high characteristic impedance outer leg and the low characteristic impedance through leg differ by lambda /4, a relative phase shift of 90 DEG is provided at the output.