Dual mode tuner for co-existing digital and analog television signals

A receiver comprising:

• an input for receiving an RF signal having a plurality of channels, wherein said channels are in either a first signal format or a second signal format;
• a conversion circuit for converting received RF signals to IF signals;
• a first signal filter receiving said IF signals from said conversion circuit and having a frequency response suitable for passing channels in said first signal format;
• and
• a second signal filter switchably coupled to an output of said first signal filter and providing a combined frequency response suitable for passing channels in said second signal format when operating with said first signal filter;
• wherein said conversion circuit includes a circuit for providing first and second reference signals, said circuit including:
• a plurality of PLLs, wherein a first PLL accepts a reference signal which is out of the bandwidth of each selected frequency, said PLLs having low phase noise and a step size resolution smaller than the loop bandwidth of the individual PLLs;
• and
• wherein said PLLs operate from input reference signals some of which are outside of said bandwidth, and at least one of which is within said bandwidth and wherein said one within said bandwidth is isolated from said output reference signals.

A receiver comprising:

• an input for receiving an RF signal having a plurality of channels, wherein said channels are in either a first signal format or a second signal format;
• a conversion circuit for converting received RF signals to IF signals;
• a first signal filter receiving said IF signals from said conversion circuit and having a frequency response suitable for passing channels in said first signal format;
• a second signal filter switchably coupled to an output of said first signal filter and providing a combined frequency response suitable for passing channels in said second signal format when operating with said first signal filter;
• and
• a coherent oscillator switchably coupled to an IF output from either said first signal filter or said second signal filter and providing a first reference signal.

A method of receiving signals comprising the steps of:

• receiving an RF signal having a plurality of channels;
• converting said RF signal to an IF signal, wherein said IF signal contains all of said plurality of channels;
• producing a filtered IF signal by selectively filtering said IF signal either through a first IF filter or through a first IF filter and a second IF filter;
• creating a first reference signal from said filtered IF signal, wherein said first reference signal is in phase with said filtered IF signal;
• and
• generating an in-phase signal by mixing said first reference signal with said filtered IF signal.

A tuner comprising:

• means for receiving an RF signal having a plurality of channels;
• means for converting said RF signal to an IF signal;
• means for selectively filtering said IF signal through a first filter or through said first filter and a second filter, wherein said first filter is suitable for passing a first format of data and a combination of said first filter and said second filter is suitable for passing a second format of data;
• means for generating a first reference signal;
• and
• means for producing a first output signal from said filtered IF signal and said first reference signal.

A receiver comprising:

• an input for receiving an RF signal having a plurality of channels, wherein said channels are in either a first signal format or a second signal format;
• a conversion circuit for converting received RF signals to IF signals;
• a first signal filter receiving said IF signals from said conversion circuit and having a frequency response suitable for passing channels in said first format;
• a substitute filter switchably replacing said first signal filter for providing a frequency response suitable for passing channels in said second format;
• and
• an input filter coupled between said receiver input and said conversion circuit for removing all frequencies above an input cutoff frequency in said RF signal;
• wherein said conversion circuit includes a circuit for providing first and second reference signals, said circuit comprising:
• a plurality of PLL, wherein a first PLL accepts a reference signal which is out of the bandwidth of each selected channel, said PLLs having low phase noise and a step size resolution smaller than the loop bandwidth of the individual PLLs;
• and
• wherein said PLL operates from input reference signals some of which are outside of said channel bandwidth, at least one of said input reference signals is within said channel bandwidth, and said at least one said input reference signal within said channel bandwidth is isolated from said output reference signals.

A receiver comprising:

• an input for receiving an RF signal having a plurality of channels, wherein said channels are in either a first signal format or a second signal format;
• a conversion circuit for converting received RF signals to IF signals;
• a first signal filter receiving said IF signals from said conversion circuit and having a frequency response suitable for passing channels in said first format;
• a substitute filter switchably replacing said first signal filter for providing a frequency response suitable for passing channels in said second format;
• and a
• a coherent oscillator switchably coupled to an IF output from either said first signal filter or said substitute signal filter and providing a first reference signal.