US 6,137,367 AGranted

High power high impedance microwave devices for power applications

AssigneeAMCOM Communications, Inc.

InventorsAmin Ezzedine, Ho C. Huang

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Abstract

Simplified, efficient multiple-transistor power amplifiers provide high power and high impedance while avoiding the use of RF power divider and combiner circuits. The input signal is directly applied to a first transistor, amplified, and supplied to the succeeding transistor, and so on, for amplification in series. Feedback is provided between the drain of the last transistor and the gates of all the transistors. Series connection of the transistors allows their power outputs and their output impedances to be summed, such that no RF output combiner is required. In a first high voltage embodiment of the amplifier of the invention, e.g., as used for satellite transmission, bias voltage is provided in series. In a second low voltage embodiment, suitable for use in cordless telephones and other battery-powered equipment, bias voltage V.sub.ds is provided separately across the drain and source terminals of each transistor, through paired chokes.

Claims26

Dependent claims

An amplifier for amplifying an input signal, comprising:

a plurality of semiconductor amplifying elements, each comprising a control terminal to which a signal may be applied for controlling the flow of current between additional input and output terminals, and a source of bias voltage providing power for said amplifying elements,
said plurality of amplifying elements being connected in series, such that the output terminal of a first element of the series is connected to the input terminal of the next element of the series, and so on, the input signal being applied to the control terminal of the first element of the series, and the output terminal of the last element of the series being connected to an output circuit, and the output terminal of the last element of the series also being connected to the control terminals of each of the elements of the series, such that the output signal from the last element of the series is supplied to the control terminals of each of the elements of the series for feedback,
wherein capacitors are connected between the control terminals of each of the amplifying elements in the series except the first and ground, the value of each said capacitor being chosen to optimize the impedance of and power output by the corresponding amplifying elements;
wherein said source of bias voltage is connected to the output terminal of the last of said elements in said series through a choke, and wherein said bias voltage is provided to each of said elements by voltage-dividing resistors in series across the control terminals of said elements;
and
wherein said output signal is supplied to the control terminals of each of the elements of the series for feedback through the same series-connected resistors used to supply bias voltage.

3 more elements

A circuit for providing high-power, high-impedance amplification of a RF signal, comprising:

a plurality of amplifying elements, each comprising input, output, and control terminals,
said plurality of amplifying elements being connected in series, such that the output terminal of the first element in the series is connected to the input terminal of the second, and so on;
an input connection for applying a RF input signal to the control terminal of the first element in the series;
an output connection connected to the output terminal of the last element in the series, for applying an amplified RF output signal to a load;
a source of bias voltage operatively connected to each of said amplifying elements;
a feedback path for supplying a portion of the output signal to the control terminals of each of the elements in the series;
capacitors connected between the control terminals of each of the amplifying elements in the series except the first and ground, the value of each said capacitor being chosen to optimize the impedance of and power output by the corresponding amplifying element;
wherein said bias voltage is provided to each of said elements by voltage-dividing resistors in series across the control terminals of said elements;
and
wherein said output signal is supplied to the control terminals of each of the elements of the series for feedback through the same series-connected resistors used to supply bias voltage.

7 more elements

A method for providing high-power, high-impedance amplification of an RF input signal, comprising the steps of:

connecting a plurality of amplifying elements, each comprising input, output, and control terminals, in series, such that the output terminal of the first element in the series is connected to the input terminal of the second, and so on;
applying an RF input signal to the control terminal of the first element in the series;
providing bias voltage to each of said amplifying elements, such that the input RP signal is amplified in each element;
connecting a load to the output terminal of the last element in the series, for applying an amplified RF output signal to the load;
feeding back a portion of the output signal to the control terminals of each of the elements in the series;
and wherein
capacitors are connected between the control terminals of each of said amplifying elements, except the first, and ground, the value of each of said capacitors being chosen to adjust the impedance of and power output by the corresponding amplifying element;
wherein said step of providing bias voltage to each of said amplifying elements is performed by providing a voltage V.sub.dd greater than the desired bias voltage V.sub.ds, and dividing V.sub.dd into smaller voltages employing a plurality of series-connected resistors;
and
wherein said plurality of series-connected resistors are connected across the control terminals of said amplifying elements, and wherein said portion of the output signal is also fed back thereby to the control terminals of said amplifying elements.

7 more elements

Dependencies are inferred from the claim text.