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VLSI Implemented 60 Mb/s QPSK/OQPSK Burst Digital Demodulator for Radio Application
Yoichi MATSUMOTO Kiyoshi KOBAYASHI Tetsu SAKATA Kazuhiko SEKI Shuji KUBOTA Shuzo KATO
IEICE TRANSACTIONS on Electronics
Publication Date: 1994/12/25
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Multimedia, Analog and Processing LSIs)
Category: Multimedia System LSIs
demodulator, carrier recovery, bit-timing recovery, VLSI, TDMA,
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This paper presents a fully digital high speed (60 Mb/s) Quadrature Phase Shift Keying (QPSK)/Offset QPSK (OQPSK) burst demodulator for radio applications, which has been implemented on a 0.5 µm Complementary Metal Oxide Semiconductor (CMOS) master slice Very Large Scale Integrated circuit (VLSI). The developed demodulator VLSI eliminates analog devices such as mixers, phase-shifters and Voltage Controlled Oscillator (VCO) for bit-timing recovery, which are used by conventional high-speed burst demodulators. In addition to the fully digital implementation, the VLSI achieves fast carrier and bit-timing acquisition in burst modes by employing a reverse-modulation carrier recovery scheme with a wave-forming filter for OQPSK operation, and a bit-timing recovery scheme with bit-timing estimation and interpolation using a pulse-shaping filter. Results of performance evaluation assuming application in Time Division Multiple Access (TDMA) systems show that the developed VLSI achieves excellent bit-error-rate and carrier-slipping-rate performance at high speed (60 Mb/s) with short preamble words (less than 100 symbols) in low Eb/No environments.