Low output impedance RF amplifier
AssigneeBlack Sand Technologies, Inc.
InventorsSusanne Paul, Marius Goldenberg
Life of this patent
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Abstract
A radio frequency (RF) power amplifier includes a low impedance pre-driver driving the input of a common-source output amplifier stage. The preamplifier includes a first transistor that has a first terminal coupled to a preamplifier RF input node, a second terminal coupled to a preamplifier RF output node, and a third terminal coupled to a supply voltage node. A first inductor is coupled between the RF output node and a bias voltage node. A voltage difference between respective first and second voltages on the RF input node and the RF output node that are substantially in phase, determines current through the first transistor.
Claims32
An apparatus comprising:
- a radio frequency (RF) power amplifier stage including,
- a first transistor having a first terminal coupled to an amplifier RF input node, a second terminal coupled to an amplifier RF output node, wherein the second terminal is a source terminal of the first transistor, and a third terminal coupled to a supply voltage node;
- a first inductor coupled between the RF output node and a bias voltage node;
- wherein current through the first transistor is determined predominantly by a difference in voltage between the RF input node and the RF output node;
- and
- wherein the first inductor is resonant with the reactance present on the RF output node.
An apparatus comprising:
- a differential radio frequency (RF) power amplifier stage including,
- a positive transistor having a first terminal coupled to an amplifier positive RF input node, a second terminal coupled to an amplifier positive RF output node, wherein the second terminal of the positive transistor is a source terminal of the positive transistor, and a third terminal coupled to a positive supply voltage node;
- a negative transistor having a first terminal coupled to an amplifier negative RF input node, a second terminal coupled to an amplifier negative RF output node wherein the second terminal of the negative transistor is a source terminal of the negative transistor, and a third terminal coupled to a negative supply voltage node;
- a positive inductor coupled between the positive RF output node and a positive bias voltage node;
- a negative inductor coupled between the negative RF output node and a negative bias voltage node;
- wherein current through the positive transistor is determined predominantly by a difference in voltage between the positive RF input node and the positive RF output node;
- wherein current through the negative transistor is determined predominantly by a difference in voltage between the negative RF input node and the negative RF output node;
- wherein the positive inductor is resonant with a reactance present on the positive RF output node, and
- wherein the negative inductor is resonant with a reactance present on the negative RF output node.
A method for operating a low impedance amplifier comprising:
- receiving an RF signal at a control terminal of a transistor;
- receiving a supply voltage at a first current carrying terminal of the transistor;
- supplying an RF output signal from a second current carrying terminal of the transistor to an RF output node, the second current carrying terminal being a source terminal of the transistor;
- achieving a higher load impedance seen by the transistor at RF frequencies by resonating an inductor coupled to the RF output node with reactance present on the RF output node;
- and
- determining current through the transistor according to a difference in voltage between the control terminal and the RF output node.
Dependencies are inferred from the claim text.