Bi-directional vector modulator/active phase shifter

Abstract

A novel bi-directional vector modulator to be used as an active phase shifter is proposed. The advantages of the active phase shifter include: 1) Compact size—By active current combining technique, short transmission lines are used to perform signal combining rather than using area-consuming Wilkinson combiner or splitter; 2) High phase resolution and flexibility—phase interpolation can be performed by vector addition through m-path vector modulators; 3) High efficiency—no signal switch loss, only switched matching capacitor; 4) Simplified signal interconnection; 5) No passive combiner needed—eliminate large size and losses in the passive combiner); 6) Can have unequal combining and/or splitting by changing the gain of vector modulator, which is difficult to realize with passive combining and/or splitting network; and 7) Can combine different signals.