A New Fully-Digitalized π/4-Shift QPSK Modulator for Personal Communication Terminals

Tetsu SAKATA  Kazuhiko SEKI  Shuji KUBOTA  Shuzo KATO  

IEICE TRANSACTIONS on Communications   Vol.E77-B   No.7   pp.921-926
Publication Date: 1994/07/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Personal, Indoor and Mobile Radio Communications)
digitalized modulator,  π/4-shift QPSK,  low power consumption,  

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This paper proposes a new fully-digitalized π/4-shift QPSK modulator consisting of a digital pulse shaping filter and a baseband quadrature modulator. By employing a novel digital filter configuration, the required filter memory is reduced to just 6.25% of the conventional one. Moreover, since the proposed baseband modulation scheme does not employ analog mixers or an analog 90 divider, a very accurate, high-stable and compact modulator is realized. It is shown that the proposed scheme achieves excellent low power consumption characteristics and is more suitable for digital LSIC implementation of personal communication terminals than a direct RF modulation scheme and an analog IF modulation scheme.