Patent ID: 7079195

Claim:
A radio frequency (RF) tuner comprising: a first mixer having a first input for receiving RF signal and a second input in communication with a first local oscillator signal, wherein said first mixer outputs a first intermediate frequency (IF) signal; a first IF filter in communication with said first mixer, wherein said first IF filter provides coarse signal selection by removing all signals outside a first selected frequency band from said first IF signal; a second mixer having a first input in communication with said first IF filter and a second input in communication with a second local oscillator signal wherein said second mixer outputs a second IF signal; a second IF filter in communication with said second mixer, wherein said second IF filter provides fine signal selection by removing all signals outside a second selected frequency band from said second IF signal, wherein said second selected frequency band is smaller than said first selected frequency band; a coherent oscillator circuit in communication with said second IF filter, wherein said coherent oscillator circuit generates an in-phase reference signal and an out-of-phase reference signal; and a video detector having a first input in communication with said second IF filter and a second input in communication with said in-phase reference signal from said coherent oscillator.