Tunable narrow-band filter including sigma-delta modulator
AssigneeXilinx, Inc.
InventorsChristopher H. Dick, Frederic J. Harris
Life of this patent
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Abstract
A tunable narrow-band filter that includes a sigma-delta modulator. In one embodiment, a conventional DC canceler is modified to include a re-quantizer in the feedback loop in the form of a ΣΔ modulator. In another embodiment, a digital receiver employs a processing chip, such as an FPGA, that includes a ΣΔ modulator to requantize oversampled control signals in the digital receiver. In still another embodiment, a wide-bandwidth sigma-delta loop has a tunable center frequency.
Claims17
A DC canceler circuit comprising:
- a. a canceler input terminal adapted to receive a series of data input samples x(n);
- b. a canceler output terminal adapted to provide a series of data output samples y(n);
- c. a feedback path having:
- i. a feedback-path input terminal connected to the canceler output terminal;
- ii. a feedback-path output terminal connected to the canceler input terminal;
- and
- iii. a sigma-delta modulator having a sigma-delta input terminal indirectly connected to the feedback-path input terminal and a sigma-delta output terminal connected to the feedback-path output terminal.
A receiver comprising:
- a. a processing chip configured to include;
- i. a data input port;
- ii. a data output port;
- iii. sigma-delta modulator connected to the data input port and having a control-signal output port;
- and
- b. a feedback path connected between the control-signal output port and the data input port.
A sigma-delta loop having a tunable center frequency, the loop comprising:
- a. a data input terminal adapted to receive data x(n);
- b. a tunable all-pass network having an all-pass network input terminal indirectly connected to the data input terminal and an all-pass network output terminal;
- c. a global feedback network connected between the all-pass network output terminal and the all-pass network input terminal;
- and
- d. a local feedback network connected between the all-pass network output terminal and the all-pass network input terminal;
- wherein the sigma delta loop is used in a control loop application.
A tunable sigma-delta loop comprising:
- a. a data input terminal adapted to receive data x(n);
- b. a first subtractor having a first input terminal, a second input terminal, and an output terminal;
- c. a second subtractor having a first input terminal connected to the output terminal of the first subtractor, a second input terminal, and an output terminal;
- d. a first adder having a first input terminal connected to the output terminal of the second adder subtractor, a second input terminal, and an output terminal;
- e. a tunable all-pass network having an all-pass network input terminal connected to the output terminal of the first adder and an all-pass network output terminal connected to the second input terminal of the first adder;
- f. a local feedback network having a local-feedback input terminal connected to the all-pass network output terminal and a local-feedback output terminal connected to the second input terminal of the second subtractor;
- g. a global feedback network having a global-feedback input terminal connected to the all-pass network output terminal and a global-feedback output terminal;
- and
- h. a quantizer having a quantizer input terminal connected to the global-feedback output terminal and a quantizer output terminal connected to the second input terminal of the first subtractor;
- wherein the sigma delta loop is used in a control loop application.
Dependencies are inferred from the claim text.