US 7,321,266 B2
Current-matching variable gain amplifier
Ming-Chou Chiang, Taipei County (Taiwan)
Assigned to Integrated System Solution Corp., Hsinchu (Taiwan)
Filed on May 17, 2005, as Appl. No. 10/908,553.
Prior Publication US 2006/0261893 A1, Nov. 23, 2006
Int. Cl. H03F 3/45 (2006.01)
U.S. Cl. 330—254 15 Claims
OG exemplary drawing
 
1. A current-matching variable gain amplifier, comprising:
a reference current source, for providing a reference current;
at least a cascode amplifier, receiving an input signal and outputting an output signal according to the reference current;
a matching circuit, coupled to the cascode amplifiers, for equaling the voltage of a first node of each of the cascode amplifiers to the voltage of a second node of the matching circuit;
a control circuit, coupled to the matching circuit, for controlling the current of a first metal oxide semiconductor field effect transistor (MOS transistor) of the matching circuit; and
at least a first blocking circuit, each of the first blocking circuit(s) corresponding with the cascode amplifier and is coupled between the reference current source and the corresponding cascode amplifier, for blocking radio frequency signals.