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Automatic Gain Control ADC based on signal statistics for a cognitive radio cross-correlation spectrum analyzer

Heusden, A.J. van (2011) Automatic Gain Control ADC based on signal statistics for a cognitive radio cross-correlation spectrum analyzer.

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Abstract:For integration purposes of a cross-correlation spectrum analyzer for cognitive radio, the use of low-resolution ADCs is investigated. In radio astronomy cross-correlation is exploited intensively together with low resolution ADCs and therefore a 2-bit ADC concept originating from ASTRON is analyzed and implemented. This ADC has automatic gain control and o�set canceling based on estimates of the cumulative distri- bution function of the input signal. The ADC is worked out at system level and simulated to verify its correctness. The comparator is a critical component in the ADC and it is implemented on circuit level in a 90 nm CMOS process. Performance dependencies on both system level and circuit level are analyzed. The ADC allows a SFDR of the spectrum analyzer of 60 dB when the measurement time is 0.2 seconds, the sample frequency is 1536 MHz and the resolution bandwidth is 6 MHz. In prac- tical cases this SFDR is lowered to 55 dB. The implemented comparator allows a SFDR of 54 dB. The AGC mechanism causes input signal de- pendency which degrades performance. The required measurement time to achieve substantial SFDR results in less e�cient spectrum estimation than when higher resolution ADCs are used.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:53 electrotechnology
Programme:Electrical Engineering MSc (60353)
Link to this item:http://purl.utwente.nl/essays/61004
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