Amplifier with improved noise performance and extended gain control range
AssigneeFreescale Semiconductor, Inc.
InventorsDaniel P. McCarthy, Lawrence E. Connell
Life of this patent
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Abstract
An amplifier and method of amplifying a signal is presented. The amplifier contains a fixed gain stage, a digitally controllable gain stage, and a continuously variable attenuator connected between the fixed and controllable gain stages. The attenuator and controllable gain stage are controllable such that the gain of the controllable gain stage is decreased when the attenuation of the attenuator reaches a predetermined maximum value and the attenuation of the attenuator is reduced thereafter. The output power level of the amplifier remains constant.
Claims23
An amplifier comprising:
- a variable attenuator having an input to receive an input signal to be attenuated, an output to supply an attenuated output signal, and a control terminal to receive a control signal from an automatic gain controller, wherein attenuation of the variable attenuator is dependent on the control signal;
- and
- a first gain stage having a controllable gain, an input of the first gain stage connected with the output of the attenuator, wherein the gain of the first gain stage is controlled by a first gain stage controller.
An electronic apparatus comprising:
- a variable attenuator having an input operable to receive an input signal to be attenuated, an output operable to supply an attenuated output signal, and a control terminal operable to receive a control signal such that attenuation of the attenuator is dependent on the control signal;
- a first gain stage having a controllable gain, the first gain stage having an output and an input connected with the output of the attenuator;
- and
- a control circuit connected with the output of the first gain stage and the control terminal of the attenuator, the control circuit operable to provide the control signal to the control terminal of the attenuator, the control circuit additionally connected with the first gain stage and operable to control the gain of the first gain stage, wherein the control circuit comprises:
- an automatic gain controller operable to provide the control signal to the control terminal of the attenuator;
- and
- a first gain stage controller operable to control the gain of the first gain stage.
A method of amplifying a signal in an amplifier comprising a variable attenuator and a controllable gain stage, the method comprising:
- receiving a signal to be attenuated;
- controlling attenuation of the attenuator with an output of an automatic gain controller, the attenuation dependent on an output level of an output of the amplifier;
- attenuating the signal to provide an attenuated signal;
- controlling gain of the controllable gain stage with a controller;
- and
- amplifying the attenuated signal using the controllable gain stage to provide a first amplified signal.
Dependencies are inferred from the claim text.