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 . A tuner for receiving information signals within a channel selected from within a plurality of channels within a predetermined frequency band, the tuner comprising:
 a first filter for providing a passband, the passband being characterized by a bandwidth sufficiently broad to admit signals in at least one of the plurality of channels with lesser attenuation than other signals;   an input port for receiving information signals and conducting the received information signals to the first filter;   an output port for conducting any signals having been admitted by the first filter; and,   superheterodyne circuitry including a mixer and a second filter for processing any signals coupled thereto and to provide them via a second output port and discriminating the received information signals within the selected channel,   wherein at least one of the first filter and the second filter comprises active and passive elements including an artificial inductance.   
   
   
       2 . A tuner as defined in  claim 1  wherein at least one of the first and second filters is integrated within a semiconductor substrate. 
   
   
       3 . A tuner as defined in  claim 1  wherein the first filter comprises active and passive elements including an artificial inductance. 
   
   
       4 . A tuner as defined in  claim 1  wherein the second filter comprises active and passive elements including an artificial inductance. 
   
   
       5 . A tuner as defined in  claim 4  wherein the first filter comprises active and passive elements including an artificial inductance. 
   
   
       6 . A tuner as defined in  claim 2  wherein the first and the second filter are integrated on the same semiconductor substrate. 
   
   
       7 . A tuner as defined in  claim 1  wherein the first filter other than comprises a surface acoustic wave (SAW) filter. 
   
   
       8 . A tuner as defined in  claim 2  wherein the integrated filter includes the first filter and is integrated within the semiconductor substrate and comprises:
 a filter selection signal port for receiving a filter selection signal; and, a plurality of bandpass filters each including a switch controlled by data derived from the filter selection signal for exclusively activating said bandpass filter.   
   
   
       9 . A tuner as defined in  claim 1  wherein the first filter comprises:
 a filter selection signal port for receiving a filter selection signal; and,   a plurality of passbands, each passband being exclusively selectable in response to the filter selection signal designating a corresponding one of the plurality of passbands, each of said passbands being characterized by a bandwidth being sufficiently broad to admit signals in at least one of the plurality of channels with lesser attenuation than other signals.   
   
   
       10 . A tuner as defined in  claim 1  wherein the one of the first and second filters is integrated within a semiconductor substrate and comprises:
 a plurality of lowpass filters and a plurality of highpass filters each comprising:   a filter selection signal port for receiving a filter selection signal; and, a switch responsive to the filter selection signal, whereby one of said highpass filters and one of said lowpass filters are activatable in pairs, some of the filters comprising active and passive elements including an artificial inductance.   
   
   
       11 . A method of tuning to a predetermined signal having a predetermined frequency band from within a plurality of channels comprising the steps of:
 receiving the plurality of channels;   providing a filter having a bandwidth being sufficiently broad to admit the signal signals in at least one of the plurality of channels with lesser attenuation than other signals, the filter comprising active and passive elements including an artificial inductance;   filtering and amplifying a channel from the plurality of channels using the filter.   
   
   
       12 . A method according to  claim 11  comprising the step of providing a single integrated circuit for tuning and filtering of the received signal absent external components for filtering thereof. 
   
   
       13 . An integrated circuit tuner front end, responsive to a tuner controller signal, for tuning to a designated information modulated signal from a plurality of multiplexed information modulated signals each in a predetermined band of frequencies, comprising:
 an input port for receiving the multiplexed information modulated signals;   a first filter for passing all the multiplexed information modulated signals and for attenuating signals that are other than the multiplexed information modulated signals;   a first amplifier for amplifying all the passed multiplexed information modulated signals from the first filter;   a first IF filter for receiving the amplified and passed multiplexed information modulated signals from the first amplifier, the first IF filter for selecting at least one of a designated information modulated signal;   a frequency conversion circuit for receiving a selected at least one of a designated information modulated signal and for converting a baseband frequency thereof; and,   a second IF filter for receiving the converted signal from the frequency conversion circuit and for passing a single designated information modulated signal to an output port thereof, the integrated tuner circuit absent an amplifier circuit electrically between the first IF filter and the second IF filter.   
   
   
       14 . An integrated circuit tuner front end according to  claim 13  wherein at least one of the first IF filter and second IF filter comprises active and passive elements including an artificial inductance. 
   
   
       15 . An integrated circuit tuner front end according to  claim 14  wherein at least two of the first filter and first IF filter and second IF filter comprise active and passive elements including an artificial inductance.