Frequency agile filter using a digital filter and bandstop filtering
First Claim
1. A frequency dependent signal attenuation apparatus, comprising:
- an input signal receiver coupled to a first directional coupler, which splits input signals into a first signal path and a second signal path;
a first RF/Analog frequency down converter coupled to the first directional coupler along the first signal path, the first RF/Analog frequency down converter having one or more down converter mixers coupled to a first filter and an analog to digital converter, and said one or more down converter mixers being controlled by a local frequency oscillator signal;
a second filter coupled to the one or more down converter mixers in the first RF/Analog frequency down converter through the first filter and analog to digital converter in the first RF/Analog frequency down converter;
a second RF/Analog frequency up converter coupled to the second filter, which Has one or more up converter mixers coupled to the second filter through a third filter and a digital to analog converter, each of said one or more up converter mixers being controlled by a local frequency oscillator signal;
a bandstop filter coupled to the second RF/analog frequency up converter, said bandstop filter provides its output signal to a second directional coupler that also receives a second signal along the second path from the first directional coupler, said signal from the first directional coupler passes through a component before being received at the second directional coupler; and
a signal output provided by the second directional coupler that includes recombined signals that have passed through the first and second paths, said signal from said first signal path attenuates the signal from the second signal path at the second directional coupler.
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Abstract
The present invention is a hybrid RF-digital signal processor-based filter for multiband radio architectures, systems capable of spectrum re-farming and software defined radios It performs low-loss frequency agile multiple notch filtering at RF where a large dynamic range exists at a filter input between signals in a stopband and passband It is a frequency dependent signal attenuation apparatus having two paths connected together by directional couplers The first path comprising a component such as a delay component or duplexer The second path comprising, in series, a down converter, a digital filter, an up converter, and a bandstop filter At the output of a power amplifier, the invention can be used to attenuate spurs, or noise within bands with strict emission constraints At the input of a low noise amplifier, the invention can be used to attenuate blockers and transmitter noise outside of the receiver passband.
20 Citations
23 Claims
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1. A frequency dependent signal attenuation apparatus, comprising:
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an input signal receiver coupled to a first directional coupler, which splits input signals into a first signal path and a second signal path; a first RF/Analog frequency down converter coupled to the first directional coupler along the first signal path, the first RF/Analog frequency down converter having one or more down converter mixers coupled to a first filter and an analog to digital converter, and said one or more down converter mixers being controlled by a local frequency oscillator signal; a second filter coupled to the one or more down converter mixers in the first RF/Analog frequency down converter through the first filter and analog to digital converter in the first RF/Analog frequency down converter; a second RF/Analog frequency up converter coupled to the second filter, which Has one or more up converter mixers coupled to the second filter through a third filter and a digital to analog converter, each of said one or more up converter mixers being controlled by a local frequency oscillator signal; a bandstop filter coupled to the second RF/analog frequency up converter, said bandstop filter provides its output signal to a second directional coupler that also receives a second signal along the second path from the first directional coupler, said signal from the first directional coupler passes through a component before being received at the second directional coupler; and a signal output provided by the second directional coupler that includes recombined signals that have passed through the first and second paths, said signal from said first signal path attenuates the signal from the second signal path at the second directional coupler. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A frequency dependent signal attenuation apparatus, comprising:
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an input signal receiver coupled to a first directional coupler, which splits input signals into a first signal path and a second signal path; a first RF/Analog frequency down converter coupled to the first directional coupler along the first signal path, the first RF/Analog frequency down converter having one or more down converter mixers coupled to a first filter and an analog to digital converter, and said one or more down converter mixers being controlled by a local frequency oscillator signal; a second filter coupled to one or more down converter mixers in the first RF/Analog frequency down converter through the first filter and analog to digital converter in the first RF/Analog frequency down converter; a second RF/Analog frequency up converter coupled to the second filter, which has one or more up converter mixers coupled to the second filter through a third filter and a digital to analog converter, each of said one or more up converter mixers being controlled by a local frequency oscillator signal; a bandstop filter coupled to the second RF/Analog frequency up converter, said bandstop filter provides its output signal to a second directional coupler that also receives a second signal along the second path from the first directional coupler, said signal from the first directional coupler passes through a component element before being received at the second directional coupler, a signal output provided by the second directional coupler includes recombined signals that have passed through the first and second pathways; and a third directional coupler coupled to the second directional coupler, which provides a signal to a third RF/Analog frequency down converter, said down converter providing a signal to a controller that provides a feedback control signal to the second filter. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of providing a frequency dependent attenuated signal comprising the steps of:
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receiving an input signal at a first directional coupler; splitting the input signal at the first directional coupler into a first signal path and a second signal path; receiving a signal along the first signal path at a first RF/Analog frequency down converter coupled to the first directional coupler, the first RF/Analog frequency down converter processing the received signal with one or more analog to digital converters, one or more down converter mixers and a first filter; providing an output signal from the first RF/Analog frequency down converter to a second filter, which processes and filters the signal provided on the first signal path; receiving the output of the second filter at a second RF/Analog frequency up converter, which processes the signal in one or more digital to analog converters, one or more up converter mixers, and a third filter; providing the signal from the second RF/Analog frequency up converter to a bandstop filter; providing a signal from the bandstop filter to a second directional coupler; and combining at the second directional coupler the output of the bandstop filter with a signal from the first directional coupler that passes through a component before being received at the second directional coupler, said combined signal produced at the output of the second directional coupler is said signal from said first signal path attenuated by the signal from said second signal path. - View Dependent Claims (20, 21, 22, 23)
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Specification