Dynamically biased amplifier
First Claim
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1. An amplifier, comprising:
- a preamplifier stage having an output terminal;
an amplifier stage for receiving an input signal from the preamplifier'"'"'s output terminal and providing an output signal; and
a control means coupled to the amplifier and preamplifier stages for initializing the amplifier stage to a first bias threshold level with a first bias signal before the amplifier stage provides the output signal, the control means further providing a second bias signal to the preamplifier and amplifier stages a predetermined time after providing the first bias signal to the amplifier stage, the amplifier stage provides the output signal in response to the second bias signal, the second bias signal increasing in bias level until it reaches a second bias threshold level which causes the control means to remove the first bias signal from the amplifier stage.
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Abstract
An amplifier (102) which can be dynamically biased is disclosed. A controller (118) determines when to change the bias to the amplifier (102), in order to achieve low frequency splatter. This is accomplished by changing the bias level of amplifier (102) between a substantially linear (class A) mode of operation, and a substantially nonlinear (class B) mode of operation. During the critical periods when the amplifier (102) is being turned into and out of operation, the amplifier (102) is placed in a substantially linear mode of operation, thereby reducing the output harmonics which develop. In another aspect of the invention a radio 300 which employs a dynamically biased amplifier (102) is disclosed.
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Citations
8 Claims
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1. An amplifier, comprising:
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a preamplifier stage having an output terminal; an amplifier stage for receiving an input signal from the preamplifier'"'"'s output terminal and providing an output signal; and a control means coupled to the amplifier and preamplifier stages for initializing the amplifier stage to a first bias threshold level with a first bias signal before the amplifier stage provides the output signal, the control means further providing a second bias signal to the preamplifier and amplifier stages a predetermined time after providing the first bias signal to the amplifier stage, the amplifier stage provides the output signal in response to the second bias signal, the second bias signal increasing in bias level until it reaches a second bias threshold level which causes the control means to remove the first bias signal from the amplifier stage. - View Dependent Claims (2, 3)
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4. A radio capable of transmitting information, comprising:
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a preamplifier stage having an output terminal; an amplifier stage for receiving an input signal from the preamplifier'"'"'s output terminal and providing an output signal; and a control means coupled to the amplifier and preamplifier stages for initializing the amplifier to a first bias threshold level with a first bias signal before the amplifier stage provides the output signal, the control means further providing a second bias signal to the preamplifier and amplifier stages a predetermined time after providing the first bias signal to the amplifier stage, the amplifier stage provides the output signal in response to the second bias signal, the second bias signal increasing in bias level until it reaches a second bias threshold level which causes the control means to remove the first bias signal from the amplifier stage. - View Dependent Claims (5, 6)
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7. A method for dynamically biasing an amplifier having an amplifier stage and a preamplifier stage, the amplifier providing an output signal, comprising the steps of:
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biasing the amplifier stage to a first bias threshold level with a first bias signal prior to the amplifier providing the output signal; applying a second bias signal which is increasing in bias level to the amplifier stage and to the preamplifier stage substantially upon the amplifier beginning to provide the output signal; and removing the first bias signal which is being applied to the amplifier stage upon the second bias signal reaching a second bias threshold level. - View Dependent Claims (8)
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Specification