A direct conversion tuner down-converts television signals, cable signals, or
other
signals directly from an RF frequency to an IF frequency and/or baseband, without
an intermediate up-conversion step for image rejection. The direct conversion tuner
includes a pre-select filter, an amplifier, an image reject mixer, and a poly-phase
filter. The pre-select filter, amplifier, and the image reject mixer can be calibrated
to provide sufficient image rejection to meet the NTSC requirements for TV signals.
The entire direct conversion tuner can be fabricated on a single semiconductor
substrate without requiring any off-chip components. The tuner configuration described
herein is not limited to processing TV signals, and can be utilized to down-convert
other RF signals to an IF frequency or baseband.