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Title: Blocker-tolerant and high-sensitivity $Δ$$\!$$Σ$ correlation digitizer for radar and coherent receiver applications

In this study, a coherent subsampling digitizer for pulsed Doppler radar systems is proposed. Prior to transmission, the radar system modulates the RF pulse with a known pseudorandom binary phase shift keying (BPSK) sequence. Upon reception, the radar digitizer uses a programmable sample-and-hold circuit to multiply the received waveform by a properly time-delayed version of the known a priori BPSK sequence. This operation demodulates the desired echo signal while suppressing the spectrum of all in-band noncorrelated interferers, making them appear as noise in the frequency domain. The resulting demodulated narrowband Doppler waveform is then subsampled at the IF frequency by a delta-sigma modulator. Because the digitization bandwidth within the delta-sigma feedback loop is much less than the input bandwidth to the digitizer, the thermal noise outside of the Doppler bandwidth is effectively filtered prior to quantization, providing an increase in signal-to-noise ratio (SNR) at the digitizer's output compared with the input SNR. In this demonstration, a delta-sigma correlation digitizer is fabricated in a 0.18-μm CMOS technology. The digitizer has a power consumption of 1.12 mW with an IIP3 of 7.5 dBm. The digitizer is able to recover Doppler tones in the presence of blockers up to 40 dBm greater thanmore » the Doppler tone.« less
ORCiD logo [1] ;  [2] ;  [2] ;  [3]
  1. Texas A & M Univ., College Station, TX (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Texas A & M Univ., College Station, TX (United States)
  3. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); U.S. Naval Research Lab., Washington, D.C. (United States)
Publication Date:
Report Number(s):
SAND-2017-2186J; SAND-2016-11563J
Journal ID: ISSN 0018-9480; 651237
Grant/Contract Number:
Accepted Manuscript
Journal Name:
IEEE Transactions on Microwave Theory and Techniques
Additional Journal Information:
Journal Volume: PP; Journal Issue: 99; Journal ID: ISSN 0018-9480
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; analog-to-digital conversion; coherent receivers; Doppler radar; RF integrated circuits; sampled data circuits; subsampling
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1372389