Quantization Noise Cancellation of Fractional-N Frequency Synthesizers Using Pre-distortion Technique
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This work proposes a novel pre-distortion technique for the quantization noise cancellation of fractional-N frequency synthesizers. The proposed technique utilizes the coordinate rotation digital computer (CORDIC) algorithm to pre-distort the baseband signal of a wireless system with the quantization noise. The pre-distorted signal then modulates the noisy output signal of the fractional-N frequency synthesizer. The transmitter (Tx) modulation quality is thereby improved. In the receiver (Rx) mode, the phase noise of the Rx carrier signal can also be improved by modulation with a pre-distorted sinusoidal signal rather than a baseband signal. Experimental results demonstrate that the novel pre-distortion technique effectively improves the modulation quality of a Tx by an error vector magnitude (EVM) of about 10 % under a 13 Mbps QPSK modulation. The carrier in-band and out-band phase noise of the fractional-N frequency synthesizer is improved by approximately 6 dB and 10 dB, respectively.
KeywordsFractional-N frequency synthesizer, delta-sigma modulation, quantization noise, CORDIC, pre-distortion
Document typePeer reviewed
Document versionFinal PDF
SourceRadioengineering. 2014, vol. 23, č. 2, s. 671-678. ISSN 1210-2512
- 2014/2