Digital TV receiver with a low IF

A TV receiver design that uses the quadrature-receiver principle is presented. Due to a low IF (intermediate frequency) of 2.6 MHz, normal video analog-to-digital (A/D) converters are sufficient to digitize the complete modulated signal. A lot of RF processing is done within the digital domain. This processing includes fine selection, separation of picture and sound, and demodulation of picture and sound. Applying the principle of analog quadrature mixing eases the integration of most parts of a front end, coming closer to the target of a `one-chip TV´. With a word length of 8 bit for the A/D converters, a satisfactory SNR of 42 dB of the video signal can be achieved. For the second sound signal, where the carrier is 20 dB below the picture carrier, the SNR is 34 dB. A good SNR needs a word length of 9 bit for the A/D converters