Patent ID: 6177964
Filing Date: 2001-01-23
Classification: H03D,H03J,H04N

Abstract:
A dual conversion IF tuner serving as the front end of a television receiver comprising:a low noise amplifier passing all channels in a received television band;a first mixer having a first input coupled to said low noise amplifier and a second input coupled to a first local oscillator signal, wherein said first mixer output a first IF signal;a first IF filter coupled to said first mixer and providing coarse channel selection, wherein said first IF filter removes all channels outside a selected frequency band from said first IF signal;a second mixer having a first input coupled to said first IF filter and a second input coupled to a second local oscillator signal;a second IF filter coupled to said second mixer and providing tine channel selection:an input filter coupled between a receiver input and said low noise amplifier, wherein said input filter removes all signals above an input cutoff frequency from received RF signals;a coherent oscillator circuit coupled to said second IF filter, wherein said coherent oscillator circuit generates an in-phase reference signal and a quadrature reference signal; anda video detector having a first input coupled to said second IF filter and a second input coupled to said in-phase reference signal from said coherent oscillator.