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Switchable amplifier circuit having reduced shutdown current

A technology of amplifier circuit and current, applied in the field of reversible power amplifier, which can solve the problem of excessive battery power consumption

Inactive Publication Date: 2006-05-03
FAIRCHILD SEMICON CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Transistor Q 1 must sink the current I of the current source, which can be as high as 5-10 mA in some applications, resulting in excessive battery power drain

Method used

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  • Switchable amplifier circuit having reduced shutdown current
  • Switchable amplifier circuit having reduced shutdown current
  • Switchable amplifier circuit having reduced shutdown current

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Embodiment Construction

[0018] Referring now to FIG. 3, RF amplifier circuit 10 is shown. Circuit 10 includes a current mirror circuit 12 . The current mirror circuit 12 includes a first current source 14 for generating a reference current I. Current source 14 is a high impedance device, where resistor R 1 express. The current mirror circuit 12 also includes an RF output transistor 16, here a bipolar transistor, preferably a heterojunction bipolar transistor (HBT) device. The output transistor 16 is set in a grounded emitter configuration, and its collector is connected to V through inductor 18 CC supply voltage, as shown. The RF input for amplification by RF output transistor 16 is coupled to the base electrode of RF output transistor 16 through an ac coupling capacitor C, as shown. The current mirror circuit 12 also includes a reference voltage generator 20, here a diode-connected bipolar transistor Q coupled to a predetermined reference voltage and to the gate electrode of the output transist...

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PUM

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Abstract

Switching amplifier circuit with current mirror. The current mirror includes: a first current source for generating a reference current; an output transistor having an input electrode and an output electrode; a current gain device connected between the output of the first current source and the input electrode of the output transistor. A bias current is generated via the output electrode of the output transistor, this bias current being a function of the reference current generated by the first current source. The second current source has an output coupled to the input of the current gain device. The second current source provides current that is part of the reference current. The output electrode of the switching transistor is coupled to: (1) the input of the current gain device; and (2) the output of the second current source. The switching transistor: (1) in response to an input signal fed to such a switching transistor, sinks current from a second current source to prevent current flow from the second current source to the current gain device and thereby de-bias the output transistor current to drive the output transistor into a non-conducting state; or (2) enabling current to flow from the second current source to the current gain device to drive the output transistor into a conducting state in response to an input signal fed to such a switching transistor.

Description

technical field [0001] This invention relates to amplifiers, and more particularly to switchable power amplifiers. Background technique [0002] As is known in the art, power amplifiers are used in a wide variety of applications. One such application is in telephones, such as battery-operated cellular telephones, for amplifying radio frequency (RF) signals. [0003] Such an RF amplifier is typically biased to the proper direct current (dc) operating point using a current mirror 9, as is also known in the art. Such a device is shown in Figure 1. Here, the amplifier consists of an RF, emitter-grounded, output transistor Q RF . The base of the RF transistor is fed with the input RF signal. The base of the output transistor is also coupled to the switching transistor Q 1 , diode-connected transistor Q 2 (i.e. p-n junction) is connected between ground and the RF output transistor Q RF between the bases. When this diode-connected transistor Q 2 When turned on, a fixed dc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03F3/04H03F3/72
CPCH03F3/72H03F3/04
Inventor 约翰·A·德法尔科米克黑尔·S·希罗柯弗
Owner FAIRCHILD SEMICON CORP