Patent ID: 6862323
Filing Date: 2005-03-01
Classification: H03D

Abstract:
1. A method of producing an M-pole low pass filter configured to simultaneously filter first and second signal channels with a high degree of phase and gain match across a passband of the first and second signal channels, the method comprising: providing a first M-pole filter channel for filtering the first signal channel, M being an integer multiple of 2 and having a value of at least 4, the first filter channel comprising a first plurality of 2-pole low pass active filter stages coupled in series to provide M-pole filtering; providing a second M-pole filter channel for filtering the second signal channel, the second filter channel comprising a second plurality of 2-pole low pass active filter stages coupled in series to provide M-pole filtering, wherein one of the second plurality of 2-pole low pass filter stages includes two variable components; and adjusting a bias of the two variable components of the second M-pole filter channel to variably control component values of the two variable components to match the gain and phase of the second filter channel to the gain and phase of the first filter channel across a desired passband.