| US 7,501,893 B2 | ||
| Variable gain amplifier circuit | ||
| Nagayoshi Dobashi, Atsugi (Japan); and Shigeki Mabuchi, Atsugi (Japan) | ||
| Assigned to Mitsumi Electric Co., Ltd., Tokyo (Japan) | ||
| Filed on Oct. 24, 2007, as Appl. No. 11/877,895. | ||
| Claims priority of application No. 2006-324045 (JP), filed on Nov. 30, 2006. | ||
| Prior Publication US 2008/0129384 A1, Jun. 05, 2008 | ||
| Int. Cl. H03F 3/45 (2006.01) | ||
| U.S. Cl. 330—254 [330/51; 330/260] | 3 Claims |
| 1. A variable gain amplifier circuit comprising:
plural differential circuits, each differential circuit having two input terminals and one output terminal, one of the input
terminals of each of the differential circuits being connected in common to a signal input terminal to input a signal to each
of the differential circuits, any one of the differential circuits being selected to operate;
an output circuit having an input terminal connected in common to each output terminal of the differential circuits and one
signal output terminal, the output circuit inputting an output signal of any of differential circuits and outputting an output
signal from the signal output terminal; and
plural resistors connected in series between the signal output terminal and a terminal to which a reference voltage is applied,
wherein:
each of junctions between the resistors is connected to one of the other input terminals of the differential circuits.
|