Tunable filter devices and methods
Analog interference filter devices and methods for isolation of desirable portions of a radio frequency signal. Signal compensation is used to provide desirable center frequency, passband width, ripple, rolloff, stopband and distortion performance. The filter is implemented with passive and/or active components.
1. A device for performing analog filtering of a signal, comprising:
a first unit comprising:
a first cell comprising:
a first splitter for splitting said signal into a first signal and a second signal;
a first channel connected to said first splitter for receiving said first signal;
a second channel having at least one of a first delay element, a first phase shifter and a first amplitude compensator, wherein said second channel is connected to said first splitter for receiving said second signal;
a first combiner for combining a signal output from said first channel with a signal output from said second channel to produce a first cell output signal;
a second cell coupled to said first cell for receiving said first cell output signal, said second cell comprising:
a second splitter for splitting said first cell output signal into a third signal and a fourth signal;
a third channel connected to said second splitter for receiving said third signal;
a fourth channel having at least one of a second delay element, a second phase shifter and a second amplitude compensator, wherein said third channel is connected to said second splitter for receiving said fourth signal;
a second combiner for combining a signal output from said third channel with a signal output from said fourth channel to produce a second cell output signal; and
a bypass for bypassing at least one of said first and second cells in accordance with a desired roll-off or stopband characteristic.
2. A device for performing analog filtering according to claim 1 , wherein said first channel comprises at least one of an amplitude compensator, a phase shifter, and a delay element.
3. A device for performing analog filtering according to claim 1 wherein said second channel further comprises a vector modulator.
4. A device for performing analog filtering according to claim 1 further comprising a second unit connected to said first unit.
5. A device for performing analog filtering according to claim 4 wherein said second unit comprises a third cell and a fourth cell.
6. A device for performing analog filtering according to claim 4 wherein said second unit is connected in parallel to said first unit.
7. A device for performing analog filtering according to claim 6 wherein said second unit is connected in series with said first unit.
8. A device for performing analog filtering according to claim 1 wherein said first delay element comprises one of the following types: fixed and variable.