Abstract A microwave amplifier and more particularly to a microwave amplifier configured as a
Doherty amplifier. In particular, the amplifier includes a carrier amplifier, a peak amplifier a
Lange coupler at the input of the amplifiers and quarter wave amplifier at the output of the
amplifiers. In order to improve isolation between the amplifiers to minimize the dependence of
each amplifier's inter-modulation (IM) performance on the others, matching networks are
provided, coupled to the output of the amplifiers. In addition, the microwave power amplifier
includes electronic tuning which allows for improved inter-modulation distortion over a wide
input power dynamic range, which allows the IM performance of the microwave amplifier to be
adjusted for the operating frequency of the amplifier.
A microwave power amplifier comprising: an input RF port a carrier amplifier having a first input and a first output a peak amplifier having a second input and a second output, said carrier amplifier and
said peak amplifier being symmetrically biased; a coupling device for coupling said first and second inputs of said carrier amplifier and
said peak amplifier to said RF input port; and an output terminal, said first and second outputs coupled to said output terminal.
Claim 2
Dependent Claim
44 words
The microwave power amplifier as recited in claim 1, wherein one or the other of said
carrier and peak amplifiers includes a biasing network configured to enable the biasing of said
one or the other of said carrier and peak amplifiers to be varied.
Claim 3
Dependent Claim
95 words
The microwave power amplifier as recited in claim 2, wherein said biasing network
includes an external source of DC voltage which enables the biasing of said one or the other of
said carrier and peak amplifiers to be varied by varying the amplitude of said DC voltage to
provide electronic tuning of said amplifier; and wherein the other of said one or the other of said
carrier and peak amplifiers includes a biasing network which provides electronic tuning of the
other of said one or the other of said carrier amplifier and said peak amplifier.
Claim 4
Dependent Claim
40 words
The microwave power amplifier as recited in claim 1, further including one or more
matching networks; and wherein said one or more matching networks include a series impedance
selected to prevent loading of said carrier amplifier by said peak amplifier.
Claim 5
Dependent Claim
21 words
The microwave power amplifier as recited in claim 4, wherein said series
impedance is a transmission line or is an inductance.
Claim 6
Dependent Claim
26 words
The microwave power amplifier as recited in claim 4, wherein said one or more
matching networks also includes a shunt impedance, coupled to said series impedance.
Claim 7
Dependent Claim
21 words
The microwave power amplifier as recited in claim 6, wherein said shunt
impedance is a capacitor, or is an open stub.
Claim 8
Dependent Claim
27 words
The microwave power amplifier as recited in claim 4, further including an impedance
transformer coupled between said one or more matching networks and said RF output terminal.
Claim 9
Dependent Claim
24 words
The microwave power amplifier as recited in claim 8, further including an output
impedance coupled between said RF output terminal and said impedance transformer.
Claim 10
Dependent Claim
48 words
The microwave power amplifier as recited in claim 1, wherein said coupler is a
Lange coupler having first and second input terminals and first and second output terminals, said
first input terminal defining said RF input port and said second input terminal coupled to an input
termination impedance.
References Cited (Backward Citations)
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