System for calibrating integrated circuit filters
AssigneeRF Magic, Inc.
InventorsAlexander C. Kurylak, Narun Sooppipatt, Iconomos A. Koullias, Esa Petri Tarvainen, Peter Jivan Shah
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Abstract
A main signal path filter is calibrated by calibrating a replica filter that tracks parametric changes in the main signal path filter. Programmed values of the replica filter determined during calibration are used to set programmed values in the main signal path filter. The main signal path filter signal does not need to be interrupted while calibration occurs. Power on testing of the main signal path filter and the replica filter can be performed to determine the parametric tracking relationship between the two filters.
Claims17
A method of calibrating a signal filter comprising the steps of:
- applying a sinusoidal test tone to a replica filter in the transition band of the replica filter;
- calibrating the replica filter amplitude at the test tone frequency and producing replica filter calibration values;
- using the replica filter calibration values to calibrate the signal filter.
An integrated circuit filter with calibration comprising:
- a main signal path filter with programmable characteristics;
- a replica filter with programmable characteristics, wherein the replica filter tracks parameter changes occurring in the main signal path filter;
- a sinusoidal test tone generator that injects a tone into the replica filter in the transition band;
- a detector for detecting the amplitude output of the replica filter and setting a programmable characteristic of the replica filter;
- and
- means for setting the main signal path filter programmable characteristics with settings used for the replica filter.
A method of calibrating a programmable filter used in a tuner to a desired frequency band, the method comprising the steps of:
- generating a sinusoidal test signal, the test signal frequency selected to be in the transition region of the desired frequency band;
- applying the test signal to the programmable filter;
- applying the test signal to an attenuator;
- comparing amplitudes of the outputs of the programmable filter and the attenuator;
- adjusting the programmable filter corner frequency to cause the filter output level to match the attenuator output level.
A calibrator for a programmable filter used in a tuner to set a desired frequency band, the calibrator comprising:
- a frequency generator for generating a sinusoidal test signal, the test signal frequency selected to be in the transition region of the desired frequency band;
- the test signal coupled to the programmable filter;
- the test signal coupled to an attenuator;
- a comparing circuit that compares the amplitude output of the programmable filter and the attenuator;
- and
- a control circuit that adjusts the programmable filter corner frequency to cause the filter output level to match the attenuator output level.
Dependencies are inferred from the claim text.