Active bias control circuit for an amplifier and method of power up sequencing the same
AssigneeHittite Microwave Corporation
InventorsFatih Kocer, Frank A. Traut, Yalcin Alper Eken, Katzin Peter
Life of this patent
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Abstract
An active bias control circuit for an amplifier includes a low dropout regulator for providing a regulated voltage to provide an input current to the amplifier, and a current sense circuit responsive to the low dropout regulator for sensing a scaled down replica of the input current to the amplifier. An amplifier control circuit adjusts a control voltage to the amplifier in response to the sensed, scaled down replica of the input current to regulate the input current to the amplifier. A method for power up sequencing an amplifier for an active bias control circuit for the amplifier is also disclosed.
Claims34
An active bias control circuit for an amplifier, comprising:
- a low dropout regulator for providing a regulated voltage and an input current to the amplifier;
- a current sense circuit responsive to the low dropout regulator for sensing a scaled down replica of the input current to the amplifier;
- and
- an amplifier control circuit for adjusting a control voltage to the amplifier in response to the sensed, scaled down replica of the input current to regulate the input current to the amplifier.
An active bias control circuit, comprising:
- a low dropout regulator for providing a regulated voltage and including a first transistor for providing an input current to the amplifier, and an error amplifier responsive to a reference voltage and the first transistor;
- a sense circuit including a second transistor having a control terminal coupled to a control terminal of the first transistor for providing and sensing the scaled down replica of the output current of the first transistor, the first and second transistors located on the same integrated circuit for matching one or more predetermined characteristics;
- and
- an amplifier control circuit for providing a control voltage to the amplifier and adjusting the control voltage of the amplifier in response to the sensed scaled down replica of the input current to keep the input current to the amplifier constant.
An active bias control circuit on an integrated circuit chip, comprising:
- a low dropout regulator for providing a regulated voltage and an input current to an amplifier;
- a current sense circuit responsive to the low dropout regulator for determining the input current to the amplifier;
- and
- an amplifier control circuit for providing a control voltage to the amplifier, the amplifier control circuit configurable to:
- provide a control voltage for an amplifier including either an enhancement mode or depletion mode device,
- operate using a negative voltage supply generated either by the integrated circuit chip or externally, and/or
- either provide a fixed control voltage or adjust the control voltage in response to the determined input current to keep the input current to the amplifier constant.
A low dropout regulator for providing a regulated voltage and an input current to an amplifier, the regulator comprising:
- a first transistor for providing an input current to the amplifier, and
- an error amplifier responsive to a reference voltage and the first transistor for adjusting the regulated voltage to the amplifier;
- a switch including a switching transistor coupled in series between the first transistor and the input of the amplifier for switching off the input current to the amplifier;
- and
- a level shifter coupled to the control terminal of the switching transistor for biasing the switching transistor.
A method for power up sequencing of an active bias controller for an external amplifier, the method comprising the steps of:
- controlling a control voltage of the amplifier to bring the amplifier control voltage below pinch off;
- if the amplifier control voltage is below pinch off, generating a first enable signal to enable supply current to flow to the amplifier;
- generating a second enable signal when the supply voltage is stabilized;
- and
- in response to the second enable signal, enabling the control voltage to achieve a predetermined amplifier input current.
Dependencies are inferred from the claim text.