RF power amplifier with load mismatch compensation
First Claim
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1. An amplifying apparatus for RF signals applied to a mismatched output load, such amplifying apparatus being compensated for output signal level reduction due to the output load mismatch and comprising:
- a first quadrature coupling means having an input port to which RF signals to be amplified are applied, an isolate port, a 0°
output port, and a -90°
output port, for coupling the RF signals in quadrature to the 0° and
-90°
output ports and coupling signals from the isolate port in quadrature to the 0° and
-90°
output ports, wherein corresponding signals on the input port and the -90°
output port are in quadrature, and corresponding signals on the isolate port and the 0°
output port are in quadrature;
a first amplifying means, having a gain G and an insertion phase β
(f), for amplifying signals from the 0°
output port;
a second amplifying means, having essentially the same gain and insertion phase as the first amplifying means, for amplifying signals from the -90°
output port;
a second quadrature coupling means having a 0°
input port, a -90°
input port, an output port, and an isolate port, the -90°
input port coupled to the output of the first amplifying means, the 0°
input port coupled to the output of the second amplifying means, the output port coupling to the mismatched output load, for combining in quadrature signals from the 0° and
-90°
input ports to the output port and combining in quadrature signals from the 0° and
-90°
input ports to the isolate port, wherein corresponding signals signals on the -90°
input port and the output port are in quadrature and corresponding signals on the 0°
input port and the isolate port are in quadrature;
an attenuator coupled to the isolate port of the second quadrature coupling means; and
means for phase shifting a signal from the attenuator to the isolate port of the first quadrature hybrid coupler, to null the phase shift of the signal out of each one of the first and second amplifying means.
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Abstract
An RF power amplifier for delivering power to a load including a first quadrature hybrid coupler driving two class C amplifiers operating with high input compression, a second quadrature hybrid coupler coupled to the outputs of the amplifiers, an attenuator, and a phase shifter. An impedance mismatch by the load causes phase-pulling of the amplifiers which reduces output to the load. This is compensated for by feeding an error signal, indicating the magnitude and phase of the phase-pulling of the two amplifiers, from the second quadrature hybrid coupler through the attenuator and the phase shifter back to the first quadrature hybrid coupler. The attenuated and phase shifted error signal adds to or is subtracted from the input signals to the two amplifiers. Therefore, one of the two amplifiers is driven with more signal and the other amplifier is driven with less signal to phase-push the two amplifiers to compensate for the phase-pulling to thereby increase the output to the load.
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Citations
5 Claims
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1. An amplifying apparatus for RF signals applied to a mismatched output load, such amplifying apparatus being compensated for output signal level reduction due to the output load mismatch and comprising:
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a first quadrature coupling means having an input port to which RF signals to be amplified are applied, an isolate port, a 0°
output port, and a -90°
output port, for coupling the RF signals in quadrature to the 0° and
-90°
output ports and coupling signals from the isolate port in quadrature to the 0° and
-90°
output ports, wherein corresponding signals on the input port and the -90°
output port are in quadrature, and corresponding signals on the isolate port and the 0°
output port are in quadrature;a first amplifying means, having a gain G and an insertion phase β
(f), for amplifying signals from the 0°
output port;a second amplifying means, having essentially the same gain and insertion phase as the first amplifying means, for amplifying signals from the -90°
output port;a second quadrature coupling means having a 0°
input port, a -90°
input port, an output port, and an isolate port, the -90°
input port coupled to the output of the first amplifying means, the 0°
input port coupled to the output of the second amplifying means, the output port coupling to the mismatched output load, for combining in quadrature signals from the 0° and
-90°
input ports to the output port and combining in quadrature signals from the 0° and
-90°
input ports to the isolate port, wherein corresponding signals signals on the -90°
input port and the output port are in quadrature and corresponding signals on the 0°
input port and the isolate port are in quadrature;an attenuator coupled to the isolate port of the second quadrature coupling means; and means for phase shifting a signal from the attenuator to the isolate port of the first quadrature hybrid coupler, to null the phase shift of the signal out of each one of the first and second amplifying means. - View Dependent Claims (2, 3)
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4. An apparatus for amplifying a radio frequency signal applied to a mismatched output load, comprising:
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first quadrature coupling means having an input port connected to receive the radio frequency signal to be amplified, an isolate port, a 0°
output port, and a -90°
output port, for coupling the radio frequency signal in quadrature to the 0° and
-90°
output ports and for coupling signals from the isolate port in quadrature to the 0° and
-90°
output ports, wherein corresponding signals on the input port and the -90°
output port are in quadrature, and corresponding signals on the isolate port and the 0°
output port are in quadrature;first amplifying means, having a gain G and an insertion phase β
(f), for amplifying signals from the 0°
output port;second amplifying means, having essentially the same gain and insertion phase as the first amplifying means, for amplifying signals from the -90°
output port;second quadrature coupling means, having a 0°
input port, a -90°
input port, an output port, and an isolate port, the -90°
input port coupled to the output of the first amplifying means, the 0°
input port coupled to the output of the second amplifying means, the output port coupling to the mismatched output load, for combining in quadrature signals from the 0° and
-90°
input ports to the output port and combining in quadrature signals from the 0° and
-90°
input ports to the isolate port, wherein corresponding signals on the -90°
input port and the output port are in quadrature and corresponding signals on the 0°
input port and the isolate port are in quadrature; andmeans for phase-pushing, having an input coupled to the isolate port of the second quadrature coupling means and an output coupled to the isolate port of the first quadrature coupling means, for compensating for the phase-pulling effect of the load mismatch to the amplifiers. - View Dependent Claims (5)
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Specification
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Current AssigneeRaytheon Company (Rtx Corporation)
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Original AssigneeRaytheon Company (Rtx Corporation)
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InventorsSelin, John R.
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Primary Examiner(s)Mullins, James B.
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Application NumberUS06/825,418Time in Patent Office428 DaysField of Search330/84, 330/53, 330/124 R, 330/149, 330/295, 328/163US Class Current330/84CPC Class CodesH03F 2200/198 A hybrid coupler being used...H03F 3/602 Combinations of several amp...
