Active Inductor Circuits for Filtering in a Cable Tuner Circuit

Abstract

An integrated front-end filter for a tuner provides an array of from several to a multitude of passbands, each for passing at least one but less than all channels designated in a band of frequencies. Each passband is exclusively selectable. The integrated front end filter includes at least one active filter unit with an active reactance element in either of fixed and variable filter configurations and a decoder coupled to said at least one active filter unit and being responsive to a control signal for selecting a one of the passbands. In one example a multitude of active filter units of fixed filter configuration provide the multitude of passbands. Each data is stored at a predetermined location and reproduced in response to a corresponding control data signal from a tuner controller. Each data characterizes one of the plurality of passbands. The filter element is switchable from one passband to another in response to the control data signal. Lower power dissipation and lesser requirements of an on-following integrated circuitry tuner permit a reduction of “off chip” connections and cost.

1 . An integrated front end filter in a tuner for providing an array of passbands, each for passing at least one but less than all channels designated in a band of frequencies, each passband of said array of passbands being exclusively selectable, the integrated front end filter comprising:
 a control signal input port for receiving a control signal;   at least one active filter unit including an active reactance element in either of fixed and variable filter configurations; and,   a decoder coupled to said at least one active filter unit and being responsive to the control signal for selecting a one of the passbands.   
   
   
       2 . An integrated front end filter in a tuner as defined in  claim 1  wherein said array of passbands is provided by a corresponding array of filter units being of said fixed filter configuration, and corresponding decoders each for exclusively activating its associated filter unit with energizing power. 
   
   
       3 . An integrated front end filter in a tuner as defined in  claim 1  wherein said array of passbands is provided by said at least one active filter unit being of said variable filter configuration, and wherein said decoder comprises:
 at least one reactive value lookup table for translating the control signal to a passband code for characterizing the function of said active reactance element.   
   
   
       4 . An integrated front end filter in a tuner for providing an array of passbands, each for passing at least one but less than all channels designated in a band of frequencies, each passband of said array of passbands being exclusively selectable, the integrated front end filter comprising:
 at least one active filter unit including an active reactance element in either of fixed and variable filter configurations; and,   a decoder coupled to said at least one active filter unit and being responsive to a control signal for selecting a one of the passbands.   
   
   
       5 . An integrated front end filter in a tuner as defined in  claim 4  wherein said array of passbands is provided by a corresponding array of filter units being of said fixed filter configuration, and corresponding decoders each for exclusively activating its associated filter unit with energizing power. 
   
   
       6 . An integrated front end filter in a tuner as defined in  claim 4  wherein said array of passbands is provided by said at least one active filter unit being of said variable filter configuration, and wherein said decoder comprises:
 at least one reactive value lookup table for translating the control signal to a passband code for characterizing the function of said active reactance element.