Patent ID: 6714602
Filing Date: 2004-03-30
Classification: H03D,H04B

Abstract:
A demodulator comprising:a first signal input terminal for receiving as an input a reception signal; a second signal input terminal for receiving as an input a local signal; a first branch circuit having a first terminal, a second terminal, and a third terminal, wherein the first terminal is connected to the first signal input terminal, branching the reception signal input to the first terminal to a signal to the second terminal and a signal to the third terminal, and branching a signal input to the second terminal to a signal to the first terminal and a signal to the third terminal; a second branch circuit having a first terminal, a second terminal, and a third terminal, branching a signal input to the first terminal to a signal to the second terminal and a signal to the third terminal, and branching a signal input to the second terminal to a signal to the first terminal and a signal to the third terminal; a third branch circuit having a first terminal, a second terminal, and a third terminal, wherein the first terminal is connected to the second signal input terminal, branching the local signal input to the first terminal to a signal to the second terminal and a signal to the third terminal, and branching a signal input to the second terminal to a signal to the first terminal and a signal to the third terminal; a first phase shifter having a first terminal and a second terminal, wherein the first terminal is connected to the second terminal of the first branch circuit and the second terminal is connected to the first terminal of the second branch circuit, and shifting the phases of a signal input from the first terminal and a signal input from the second terminal and outputting them from the second terminal and the first terminal; a second phase shifter having a first terminal and a second terminal, wherein the first terminal is connected to the second terminal of the second branch circuit and the second terminal is connected to the second terminal of the third branch circuit, and shifting the phases of a signal input from the first terminal and a signal input from the second terminal and outputting them from the second terminal and the first terminal; a first signal level detection circuit having an input terminal connected to the third terminal of the first branch circuit and detecting a level of a signal output from the third terminal of the first branch circuit; a second signal level detection circuit having an input terminal connected to the third terminal of the second branch circuit and detecting a level of a signal output from the third terminal of the second branch circuit; and a third signal level detection circuit having an input terminal connected to the third terminal of the third branch circuit and detecting a level of a signal output from the third terminal of the third branch circuit.