Patent ID: 7342987
Filing Date: 2008-03-11
Classification: H03H,H03K

Abstract:
1. A 90-degree phase shifter comprising: a T flip-flop including a first variable current source that is connected to a node between the first input transistor and the dual differential circuit; a second variable current source that is connected to a node between the second input transistor and the dual differential circuit; a third variable current source that is connected to a node between the third input transistor and the dual differential circuit; a fourth variable current source that is connected to a node between the fourth input transistor and the dual differential circuit; and a phase comparator that compares phase differences between signals outputted from the T flip-flop in order to output signals commensurate with results of comparison, wherein the first to fourth variable current sources are controlled by signals based on the signals outputted from the phase comparator.