Direct conversion tuner
AssigneeBroadcom Corporation
InventorErlend Olson
Life of this patent
Estimating the term…
Abstract
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.
Claims21
1-55. (canceled)
A tuner, comprising:
- a pre-select filter that receives a plurality of channels;
- an amplifier that is coupled to said pre-select filter;
- an image reject mixer that is coupled to said amplifier;
- an IF filter coupled to an output of said image reject mixer;
- means for determining an IQ imbalance of one of said pre-select filter and said amplifier;
- and
- means for correcting said IQ imbalance determined by said means for determining.
A tuner, comprising:
- a pre-select filter that receives a plurality of channels;
- an amplifier having an input coupled to an output of said pre-select filter;
- an image reject mixer having an input coupled to an output of said pre-select filter;
- a local oscillator coupled to said image reject mixer;
- an IF filter coupled to an output of said image reject mixer, said IF filter combining I and Q outputs of said image reject mixer;
- wherein said image reject mixer directly down converts a selected channel from said plurality of channels to an IF frequency that is within a passband of said IF filter, said selected channel determined by a frequency of said local oscillator;
- wherein an IQ imbalance of one of said pre-select filter and said amplifier is determined during a calibration period based on injecting a local oscillator signal from said local oscillator into an input of said pre-select filter.
In a tuner that processes an RF signal having a plurality of channels, said tuner having tuner components that include a pre-select filter, an amplifier, an image reject mixer, all of which are serially coupled, a method of determining an IQ imbalance in one or more of said tuner components at a selected channel of said plurality of channels, the method comprising the steps of:
- generating a test signal having a frequency that corresponds to said selected channel;
- injecting said test signal into an input of said pre-select filter;
- and
- examining an output of one of said pre-select filter, said amplifier, and said image reject mixer to determine a corresponding IQ imbalance.
Dependencies are inferred from the claim text.