Method and apparatus for compensation of cross modulation effects
OwnerBo Lindellinventor
Life of this patent
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Abstract
The present invention relates generally to a method and apparatus for cross modulation compensation in RF devices giving rise to cross modulation. A test signal as well as a wanted signal are applied to the RF device in which cross modulation appears. The cross modulation experienced by the test signal is measured, and the result hereby obtained is used for cross modulation compensation of the wanted signal at the RF device output.
Claims24
A method for reducing the effects of cross modulation of an RF signal applied to an amplifier or mixer (105,310), the amplifier or mixer (105,310) operable in a pass band, the method characterised by the following steps:
- generating a test signal;
- simultaneously applying the RF signal and the test signal to said amplifier or mixer (105, 310) in order to obtain an amplified or mixed RF signal and an amplified or mixed test signal;
- detecting the amplified or mixed test signal;
- measuring the amplitude modulation of the amplified or mixed test signal;
- generating a test signal AM detector output representing the amplitude modulation measured in the step of measuring;
- compensating the amplified or mixed RF signal for cross modulation effects by using said test signal AM detector output.
An electronic circuit for cross modulation compensation of an RF signal, the RF signal applied to an amplifier or mixer (105, 310) forming a part of the electronic circuit, the electronic circuit characterised by:
- a test signal generator (110) for generating a test signal to be applied, simultaneously to the RF signal, to the amplifier or mixer (105, 310);
- a test signal filter (115) operable on an extracted part of the amplified or mixed RF signal for filtering out the amplified or mixed test signal;
- a test signal AM detector (120) for detecting the amplified or mixed test signal at the output of the test signal filter and for measuring the amplitude modulation of the amplified or mixed test signal, the test signal AM detector (120) capable of generating a test signal AM detector output representing the amplitude modulation of the amplified or mixed test signal;
- and
- cross modulation compensating means (130, 205) for cross modulation compensating the amplified or mixed RF signal by use of said test signal AM detector output.
Dependencies are inferred from the claim text.