SUPPRESSION CIRCUIT FOR SUPPRESSING UNWANTED TRANSMITTER OUTPUT
First Claim
1. A suppression circuit for suppressing unwanted output from an amplifier having an input and an output, the input receiving an input signal, and the amplifier operable over a frequency band and operable to amplify the input signal to produce an amplified output signal, the suppression circuit connected between the input of the amplifier and the output of the amplifier, the suppression circuit comprising:
- a signal coupler coupled to the output of the amplifier, and arranged to provide a feedback signal derived from the amplified output signal;
a signal processing circuit arranged to receive the feedback signal, and configured to process the feedback signal to generate a negative feedback signal at a selected frequency within the frequency band of the amplifier; and
a further signal coupler coupled to the input of the amplifier, and arranged to receive the input signal and the negative feedback signal, and arranged to couple the negative feedback signal to the input signal, such that when the input signal is amplified by the amplifier any signals at the selected frequency can be suppressed.
1 Assignment
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Accused Products
Abstract
Aspects of the disclosure relate to a frequency suppression circuit arrangement, which allows at least one selected frequency band to be suppressed by coupling the frequency suppression circuit between the input and output of an RF power amplifier. The frequency circuit in the embodiments of the disclosure down-converts a feedback signal derived from the amplified output signal into baseband signals. Each of the baseband signals is fed into an inverting amplifier to generate a negative baseband signal. The negative baseband signal is subsequently filtered to selectively pass the negative baseband signal. The filtered signal is subsequently up-converted into an RF signal. The up-converted RF signal is combined and provided to a coupler connected at the input of the power amplifier such that when the input signal is amplified by the RF power amplifier any signals at the selected frequency can be suppressed.
18 Citations
20 Claims
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1. A suppression circuit for suppressing unwanted output from an amplifier having an input and an output, the input receiving an input signal, and the amplifier operable over a frequency band and operable to amplify the input signal to produce an amplified output signal, the suppression circuit connected between the input of the amplifier and the output of the amplifier, the suppression circuit comprising:
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a signal coupler coupled to the output of the amplifier, and arranged to provide a feedback signal derived from the amplified output signal; a signal processing circuit arranged to receive the feedback signal, and configured to process the feedback signal to generate a negative feedback signal at a selected frequency within the frequency band of the amplifier; and a further signal coupler coupled to the input of the amplifier, and arranged to receive the input signal and the negative feedback signal, and arranged to couple the negative feedback signal to the input signal, such that when the input signal is amplified by the amplifier any signals at the selected frequency can be suppressed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 18)
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10. A multi-frequency suppression circuit for suppressing unwanted outputs at multiple frequencies from an amplifier having an input and an output, the input receiving an input and the amplifier operable over a frequency band and operable to amplify the input signal to produce an amplified output signal, the multi-frequency suppression circuit connected between the input of the amplifier and the output of the amplifier, the multi-frequency suppression circuit comprising:
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a signal coupler coupled to the output of the amplifier, and arranged to provide a feedback signal derived from the amplified output signal; a signal splitter configured to split the feedback signal into a plurality of feedback signals; a plurality of sets of signal processing circuits, the sets respectively arranged to receive one of said plurality of feedback signals, and configured to process said one of said plurality of feedback signals to generate a respective negative feedback signal at a selected frequency within the frequency band of the amplifier; a signal combiner configured to combine said generated negative feedback signals from said signal processing circuits to produce a combined negative feedback signal; and a further signal coupler coupled to the input of the amplifier, and arranged to receive the input signal and the combined negative feedback signal, and arranged to couple the combined negative feedback signal to the input signal, such that when the input signal is amplified by the amplifier any signal at the selected frequencies can be suppressed. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 19)
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20. A method of suppressing unwanted transmitter output in a radio frequency (RF) amplifier, comprising:
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obtaining a feedback signal from the output of the RF amplifier; downconverting an excision frequency band of the feedback signal to one or more feedback signal baseband components, the excision frequency band being a band that it is desired to remove from the output of the RF amplifier; low pass filtering the feedback signal baseband components to remove signals outside the excision frequency band; upconverting the filtered feedback signal baseband components to RF; and feeding back the unconverted feedback signal to an input of the RF amplifier; the method further comprising inverting the feedback signal at any point in the signal processing chain to provide a negative feedback signal to the input of the RF amplifier.
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Specification