HDTV data carrier separation using a multiplexing filter

An interleaving, symbol-shaping quadrature demodulator architecture that demodulates the two data carriers in the digital video signal used in the advanced digital high definition television (AD-HDTV) system is described. The demodulator accepts separate 10-b digitized intermediate frequency (IF) data input, for both carriers, to produce spectrally shaped inphase and quadrature baseband signals using only one decimate-by-two 58-tap multiplexed finite-impulse-response (FIR) filter. A 15.36-MHz multiplexed FIR filter has been designed from a high-level description of the filter characteristics using a technology-independent, silicon generator approach. The 58-tap FIR filter achieves the 17% excess bandwidth and the 40-dB attenuation required by the AD-HDTV system. It also achieves an intersymbol interference of 29 dB. The interleaving, all-digital spread-spectrum quadrature amplitude modulation (SS-QAM) demodulator chip is fabricated in a 1.0-μm CMOS N-well process, contains 48 K transistors, and has a die area of 34 mm² and an estimated 359-mW power dissipation with a 5-V power supply. This architecture makes possible a single-chip, low-cost demodulator