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Title: Delta Modulation Technique for Improving the Sensitivity of Monobit Subsamplers in Radar and Coherent Receiver Applications

Abstract

This paper introduces a technique for improving the sensitivity of RF subsamplers in radar and coherent receiver applications. The technique, referred to herein as “delta modulation” (DM), feeds the time-average output of a monobit analog-to-digital converter (ADC) back to the ADC input, but with opposite polarity. Assuming pseudo-stationary modulation statistics on the sampled RF waveform, the feedback signal corrects for aggregate DC offsets present in the ADC that otherwise degrade ADC sensitivity. Two RF integrated circuits (RFICs) are designed to demonstrate the approach. One uses analog DM to create the feedback signal; the other uses digital DM to achieve the same result. A series of tests validates the designs. The dynamic time-domain response confirms the feedback loop’s basic operation. Measured output quantization imbalance, under noise-only input drive, significantly improves with the use of the DM circuit, even for large, deliberately induced DC offsets and wide temperature variation from -55°C to +85 °C. Examination of the corrected vs. uncorrected baseband spectrum under swept input signal-tonoise ratio (SNR) conditions demonstrates the effectiveness of this approach for realistic radar and coherent receiver applications. In conclusion, two-tone testing shows no impact of the DM technique on ADC linearity.

Authors:
 [1];  [1];  [1];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1140866
Report Number(s):
SAND2014-2348J
Journal ID: ISSN 0018-9480; 505919
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
IEEE Transactions on Microwave Theory and Techniques
Additional Journal Information:
Journal Volume: 62; Journal Issue: 8; Journal ID: ISSN 0018-9480
Publisher:
IEEE
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; Analog-to-digital conversion; Doppler radar; RF integrated circuits (RFICs); coherent receivers; sampled data circuits

Citation Formats

Rodenbeck, Christopher T., Tracey, Keith J., Barkley, Keith R., and DuVerneay, Brian B. Delta Modulation Technique for Improving the Sensitivity of Monobit Subsamplers in Radar and Coherent Receiver Applications. United States: N. p., 2014. Web. doi:10.1109/TMTT.2014.2332433.
Rodenbeck, Christopher T., Tracey, Keith J., Barkley, Keith R., & DuVerneay, Brian B. Delta Modulation Technique for Improving the Sensitivity of Monobit Subsamplers in Radar and Coherent Receiver Applications. United States. doi:10.1109/TMTT.2014.2332433.
Rodenbeck, Christopher T., Tracey, Keith J., Barkley, Keith R., and DuVerneay, Brian B. Fri . "Delta Modulation Technique for Improving the Sensitivity of Monobit Subsamplers in Radar and Coherent Receiver Applications". United States. doi:10.1109/TMTT.2014.2332433. https://www.osti.gov/servlets/purl/1140866.
@article{osti_1140866,
title = {Delta Modulation Technique for Improving the Sensitivity of Monobit Subsamplers in Radar and Coherent Receiver Applications},
author = {Rodenbeck, Christopher T. and Tracey, Keith J. and Barkley, Keith R. and DuVerneay, Brian B.},
abstractNote = {This paper introduces a technique for improving the sensitivity of RF subsamplers in radar and coherent receiver applications. The technique, referred to herein as “delta modulation” (DM), feeds the time-average output of a monobit analog-to-digital converter (ADC) back to the ADC input, but with opposite polarity. Assuming pseudo-stationary modulation statistics on the sampled RF waveform, the feedback signal corrects for aggregate DC offsets present in the ADC that otherwise degrade ADC sensitivity. Two RF integrated circuits (RFICs) are designed to demonstrate the approach. One uses analog DM to create the feedback signal; the other uses digital DM to achieve the same result. A series of tests validates the designs. The dynamic time-domain response confirms the feedback loop’s basic operation. Measured output quantization imbalance, under noise-only input drive, significantly improves with the use of the DM circuit, even for large, deliberately induced DC offsets and wide temperature variation from -55°C to +85 °C. Examination of the corrected vs. uncorrected baseband spectrum under swept input signal-tonoise ratio (SNR) conditions demonstrates the effectiveness of this approach for realistic radar and coherent receiver applications. In conclusion, two-tone testing shows no impact of the DM technique on ADC linearity.},
doi = {10.1109/TMTT.2014.2332433},
journal = {IEEE Transactions on Microwave Theory and Techniques},
number = 8,
volume = 62,
place = {United States},
year = {Fri Aug 01 00:00:00 EDT 2014},
month = {Fri Aug 01 00:00:00 EDT 2014}
}

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