MULTIPLE FREQUENCY CONVERTER USING DIGITAL MIXERS

摘要

When using a DSP to digitally predistort the RF input to a power amplifier, it is necessary to downconvert the frequency the of the input signal to enable it to be processed by the DSP. The predistored amplifier input signal produced by the DSP is then upconverted to its original frequency and supplied to the power amplifier. The downconverter and the upconverter processes each comprise a number of mixers that operate in series upon the amplifier input signal. Each of the mixers mixes a respective reference signal into the amplifier input signal to change the latter's frequency. All of the reference signals are derived from the same reference oscillator. If the total number of mixers that perform high-sided mixing is constrained to be even, then frequency errors associated with the downconversion and subsequent upconversion are eliminated.