US 7,843,257 B2Granted

Active filter calibration method and apparatus

AssigneeMaxim Integrated Products, Inc.

InventorsTheron Jones, Luiz Antonio Razera, Jr., Andrew Zocher

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Abstract

An example bandpass filter calibration system includes a MUX, first and second signal sources coupled to inputs of the MUX, a bandpass filter coupled to an output of the MUX, a rectification circuit including a plurality of rectifiers having a corresponding plurality of rectifier outputs coupled to an output of the bandpass filter, a summer having a plurality of inputs coupled to the plurality of rectifier outputs, a low pass filter coupled to an output of the summer, an ADC coupled to an output of the low pass filter, and a calibration processor unit coupled to an output of the ADC. The calibration processor unit controls the MUX to selectively apply the first signal source and the second signal source to the bandpass filter and calibrates the bandpass filter by a least one of increasing filter center frequency and decreasing filter center frequency of the bandpass filter.

Claims20

Dependent claims

A bandpass filter calibration apparatus comprising:

a MUX having a plurality of inputs, an output and a control input;
a first signal source of a frequency f0 coupled to a first input of said MUX;
a second signal source of a frequency f1 coupled to a second input of said MUX;
a bandpass filter having an input coupled to said output of said MUX, an output and a control input;
a rectification circuit having an input coupled to an output of said bandpass filter, said rectification circuit comprising a plurality of rectifiers having a corresponding plurality of rectifier outputs;
a summer having a plurality of inputs coupled to said plurality of rectifier outputs;
a low pass filter having an input coupled to an output of said summer;
an ADC having an input coupled to an output of said low pass filter;
and
a calibration processor unit having an input coupled to an output of said ADC, said calibration processor unit having a MUX control output coupled to said control input of said MUX and a filter control output coupled to said control input of said bandpass filter, wherein said calibration processor unit controls said MUX to selectively apply said first signal source and said second signal source to said bandpass filter and calibrates said bandpass filter by a least one of increasing filter center frequency and decreasing filter center frequency.

7 more elements

Dependencies are inferred from the claim text.