FM tuner with band extraction and optimization of a PLL FM demodulator

Claim 2

A FM tuner for receiving a FM signal and developing a FM detected output in response to a select signal for controlling the filter characteristics of the FM tuner, comprising: band converting means for converting the band of said FM signal from a high frequency band into an intermediate frequency band; band component extracting means for extracting a portion of a band component from the FM signal converted in band by said band converting means in response to said select signal; demodulating means having a phase locked loop for FM demodulating said FM signal by employing said phase locked loop in response to said select signal; and optimizing means responsive to a bandwidth of the signal extracted by said band component extracting means for optimizing a lock range of the phase locked loop of said demodulating means in response to said select signal.

Claim 3

A FM tuner according to claim 1, wherein said band component extracting means comprises a plurality of bandpass filters for extracting signals having a plurality of bandwidths and selecting means for selecting one bandpass filter out of said plurality of bandpass filters in response to said select signal.

Claim 4

A FM tuner according to claim 2, wherein said optimizing means comprises input signal level switching means for switching the level of an input signal to be transmitted to said demodulating means in response to an extraction bandwidth of said band component extracting means determined by said one bandpass filter selected by said selecting means.

Claim 5

A FM tuner according to claim 3, wherein said input signal level switching means comprises a first path for transmitting therethrough said FM signal having a band width extracted by said band component extracting means directly to said demodulating means; a second path for attenuating or amplifying said FM signal having a bandwidth extracted by said band component extracting means and transmitting the attenuated or amplified FM signal to said demodulating means and enabling means responsive to said select signal from said selecting means for enabling said first path or said second path.

Claim 6

A FM tuner according to claim 4, wherein said second path comprises an attenuator.

Claim 7

A FM tuner according to claim 4, wherein said second path comprises an amplifier.

Claim 8

A FM tuner according to claim 2, wherein said demodulating means comprises a phase comparator, a voltage controlled oscillator, and a loop filter connected between an output of said phase comparator an input of said voltage controlled oscillator.

Claim 9

A FM tuner according to claim 7, wherein said optimizing means comprises gain control means for switching a gain of said loop filter in response to the extraction bandwidth of said band component extracting means.

Claim 10

A FM tuner for receiving a FM signal and developing a FM detected output, comprising: amplifying/converting means for amplifying said FM signal and converting the band of the amplified signal from a high frequency band into an intermediate frequency band; first extracting means for extracting a first band component from the FM signal converted into the intermediate frequency band by said amplifying/converting means; second extracting means for extracting a second band component having a more narrow bandwidth than the bandwidth of said first band component from the FM signal converted into the intermediate frequency band by said amplifying/converting means; demodulating means comprising a phase locked loop having a lock range optimized for a first extraction bandwidth of said first extracting means for demodulating said FM signal by employing said phase locked loop; and means for applying said first band component extracted by said first extracting means to said demodulating means, while said first extracting means is being selected by said selecting means, and for attenuating the second band component extracted by said second extracting means so that the lock range of said phase locked loop is optimized for a second extraction bandwidth of said second extracting means, and applying the attenuated second band component to said demodulating means, while said second extracting means is being selected by said selecting means.

Claim 11

A FM tuner for receiving a FM signal and developing a FM detected output, comprising: amplifying/converting means for amplifying said FM signal and converting the band of the amplified signal from a high frequency band into an intermediate frequency band; first extracting means for extracting a first band component from the FM signal converted into the intermediate frequency band by said amplifying/converting means; second extracting means for extracting a second band component having a more narrow bandwidth than the bandwidth of said first band component from the FM signal converted into the intermediate frequency band by said amplifying/converting means; demodulating means comprising a phase locked loop having a lock range optimized for a first extraction bandwidth of said first extracting means for demodulating said FM signal by employing said phase locked loop; and means for applying said first band component extracted by said first extracting means to said demodulating means, while said first extracting means is being selected by said selecting means, and for attenuating the second band component extracted by said second extracting means so that the lock range of said phase locked loop is optimized for a second extraction bandwidth of said second extracting means, and applying the attenuated second band component to said demodulating means, while said second extracting means is being selected by said selecting means.

Claim 12

A FM tuner for receiving a FM signal and developing a FM detected output in response to a select signal for controlling the filter characteristics of the FM tuner, comprising: band converting means for converting the band of said FM signal from a high frequency band into an intermediate frequency band; band component extracting means for extracting a portion of a band component from the FM signal converted in band by said band converting means in response to said select signal, said band component extracting means including, a plurality of bandpass filters for extracting signals having a plurality of bandwidths, and selecting means for selecting one bandpass filter out of said plurality of bandpass filters in response to said select signal; demodulating means having a phase locked loop for FM demodulating said FM signal by employing said phase locked loop in response to said select signal said demodulating means including a phase comparator, a voltage controlled oscillator, and a loop filter connected between an output of said phase comparator and an input of said voltage controlled oscillator; and optimizing means responsive to a bandwidth of the signal extracted by said band component extracting means for optimizing a lock range of said phase locked loop of said demodulating means in response to said select signal, said optimizing means including gain control means for switching a gain of said loop filter in response to the extraction bandwidth of said band component extracting means.

Claim 13

A FM tuner for receiving a FM signal and developing a FM detected output in response to a select signal for controlling the filter characteristics of the FM tuner, comprising: band converting means for converting the band of said FM signal from a high frequency band into an intermediate frequency band; band component extracting means for extracting a portion of a band component from the FM signal converted in band by said band converting means in response to said select signal, said band component extracting means including, a plurality of bandpass filters for extracting signals having a plurality of bandwidths, and selecting means for selecting one bandpass filter out of said plurality of bandpass filters in response to said select signal; demodulating means having a phase locked loop for FM demodulating said FM signal by employing said phase locked loop in response to said select signal said demodulating means including a phase comparator, a voltage controlled oscillator, and a loop filter connected between an output of said phase comparator and an input of said voltage controlled oscillator; and optimizing means responsive to a bandwidth of the signal extracted by said band component extracting means for optimizing a lock range of said phase locked loop of said demodulating means in response to said select signal, said optimizing means including gain control means for switching a gain of said loop filter in response to the extraction bandwidth of said band component extracting means.

Claim 14

A FM tuner for receiving a FM signal and developing a FM detected output in response to a select signal for controlling the filter characteristics of the FM tuner, comprising: band converting means for converting the band of said FM signal from a high frequency band into an intermediate frequency band; band component extracting means for extracting a portion of a band component from the FM signal converted in band by said band converting means in response to said select signal, said band component extracting means including, a plurality of bandpass filters for extracting signals having a plurality of bandwidths, and selecting means for selecting one bandpass out of said plurality of bandpass filters in response to said select signal; demodulating means having a phase locked loop for FM demodulating said FM signal by employing said phase locked loop in response to said select signal, and optimizing means responsive to a bandwidth of the signal extracted by said band component extracting means for optimizing a lock range of said phase locked loop of said demodulating means in response to said select signal, said optimizing means including input signal level switching means for switching the level of an input signal to be transmitted to said demodulating means in response to an extraction bandwidth of said band component extracting means determined by said one bandpass filter selected by said selecting means.

Claim 15

A FM tuner for receiving a FM signal and developing a FM detected output in response to a select signal for controlling the filter characteristics of the FM tuner, comprising: band converting means for converting the band of said FM signal from a high frequency band into an intermediate frequency band; band component extracting means for extracting a portion of a band component from the FM signal converted in band by said band converting means in response to said select signal, said band component extracting means including, a plurality of bandpass filters for extracting signals having a plurality of bandwidths, and selecting means for selecting one bandpass out of said plurality of bandpass filters in response to said select signal; demodulating means having a phase locked loop for FM demodulating said FM signal by employing said phase locked loop in response to said select signal, and optimizing means responsive to a bandwidth of the signal extracted by said band component extracting means for optimizing a lock range of said phase locked loop of said demodulating means in response to said select signal, said optimizing means including input signal level switching means for switching the level of an input signal to be transmitted to said demodulating means in response to an extraction bandwidth of said band component extracting means determined by said one bandpass filter selected by said selecting means.

Claim 16

A FM tuner according to claims 11, wherein said input signal level switching means comprises a first path for transmitting therethrough said FM signal having a bandwidth extracted by said band component extracting means directly to said demodulating means; a second path for attenuating or amplifying said FM signal having a bandwidth extracted by said band component extracting means and transmitting the attenuated or amplified FM signal to said demodulating means; and enabling means responsive to said select signal from said selecting means for enabling said first path or said second path.

Claim 17

A FM tuner according to claim 12, wherein said second path comprises an attenuator.

Claim 18

A FM tuner according to claim 12, wherein, said second path comprises an amplifier.