Patent Number: 7,714,644

Title: Amplifier circuit

Abstract: An amplifier circuit block and a compensation circuit block are provided. The amplifier circuit block includes an analog adder for subtracting an output signal of the compensation circuit block from an input signal and an amplifier circuit operating in a wide band. The compensation circuit block includes an amplifier circuit with a low offset voltage and a low noise in a low frequency region, an analog adder block for subtracting an output signal of the amplifier circuit from an output signal of the amplifier circuit and generating a differential signal thereof, and a feedback circuit block for negatively feeding back the differential signal to the analog adder. The amplifier circuit block can reduce the offset voltage and the low-band noise by the negative feedback of the differential signal, and at the same time, the operation band of the entire amplifier circuit can be decided by the characteristic of the amplifier circuit.

Inventors: Takemoto; Takashi (Kokubunji, JP), Yamashita; Hiroki (Hachioji, JP), Saito; Tatsuya (Kunitachi, JP)

Assignee: Hitachi, Ltd.

International Classification: H03F 1/02 (20060101)

Expiration Date: 5/11/12018