Patent ID: 6803821
Filing Date: 2004-10-12
Classification: H03F

Abstract:
An amplifier circuit, comprising:(a) a current mirror circuit comprising: (i) a first current source for producing a reference current; (ii) an output transistor having an input electrode and an output electrode; (iii) a current gain device connected between an output of the first current source and the input electrode of the output transistor; (v) wherein a bias current is produced through the output electrode of the output transistor, such bias current being a function of the reference current produced by the first current source; (b) a second current source having an output coupled to an input of the current gain device, such second current source providing a current which is a fraction of the reference current; and (c) a switching transistor having an output electrode coupled to: (1) an input of the current gain device; and, (2) an output of the second current source, such switching transistor: (1) sinking the current from the second current source in response to an input signal fed to such switching transistor inhibiting current from the second current source to pass to the current gain device and thereby remove the bias current for the output transistor driving the output transistor to a non-conducting condition; or (2) enabling the current from the second current source to pass to the current gain device in response to the input signal fed to such switching transistor driving the output transistor to a conducting condition.