Patent ID: 7266062

Claim:
A signal output circuit comprising: a 180-degree phase shifting circuit for shifting a phase of an input signal by an odd multiple of 180 degrees, wherein the 180-degree phase shifting circuit further comprises: a second operational amplifier having a non-inverted input terminal, an inverted input terminal, and an output terminal, first through fourth resistors, and a first capacitor and a second capacitor; and a first operational amplifier having first and second input terminals and an output terminal, the first and second input terminals having a different polarity, wherein the input signal is input into the first input terminal, wherein a 180-degree shifted signal output from the 180-degree phase shifting circuit is input to the second input terminal, wherein a difference between the input signal and the 180-degree shifted signal is output from the output terminal of the first operational amplifier, wherein the input signal is input to the inverted input terminal via the first resistor, the first capacitor, and the third resistor, and input to the inverted input terminal via the first resistor and the second capacitor, and wherein an output of the output terminal of the second operational amplifier is fed back to the inverted input terminal via the third resistor, and fed back to the inverted input terminal via the first capacitor and the second capacitor, and fed back to a signal input side of the first resistor via the fourth resistor and the second resistor.