METHODS AND SYSTEMS FOR CALIBRATING AN ANALOG FILTER

摘要

Devices and methods capable of addressing filter responses are disclosed. For example, a method for compensating a first low-pass filter and a second low-pass filter is disclosed. The method includes injecting a reference tone fR and a cutoff tone fC into the first low-pass filter, and measuring respective filter responses of the reference tone fR and the cutoff tone fC while changing capacitor codes that control a cutoff frequency of the first low-pass filter until a first capacitor code ICODE is determined that most accurately causes the first low-pass filter to utilize a desired cutoff frequency f0, performing a similar operation for the second low-pass filter until a second capacitor code QCODE is determined, and calibrating for mismatch between the first low-pass filter and the second low-pass filter.

主权项

1. A method for compensating for non-idealities in a filter circuit that includes programmable filter circuitry including a first low-pass filter and a second low-pass filter both having a common desired cutoff frequency f0, the method comprising:
for a first desired bandwidth BW0 corresponding to the common desired cutoff frequency f0, injecting a reference tone fR and a cutoff tone fC into the first low-pass filter, and measuring respective filter responses of the reference tone fR and the cutoff tone fC while changing capacitor codes that control a cutoff frequency f0-I of the first low-pass filter until a first capacitor code ICODE is determined that most accurately causes the first low-pass filter to utilize the desired cutoff frequency f0; for the first desired bandwidth BW0, injecting the reference tone fR and the cutoff tone fC into the second low-pass filter, and measuring respective filter responses of the reference tone fR and the cutoff tone fC while changing capacitor codes that control a cutoff frequency f0-Q of the second low-pass filter until a second capacitor code QCODE is determined that most accurately causes the second low-pass filter to utilize the desired cutoff frequency f0; and further calibrating for mismatch between the first low-pass filter and the second low-pass filter for one or more additional bandwidths greater than the first desired bandwidth BW0.