Efficient implementation of an I-Q GMSK modulator

An efficient implementation of GMSK modulators achieved by taking advantage of symmetry properties of the premodulation filter is described. The design bypasses typical processing steps such as modulating waveform ROM lookup, integration, and sine/cosine ROM lookup, and therefore does not introduce the related errors. A design for a cordless telephony IC with a bit rate of 72 kbps and 64 samples per symbol was implemented using only simple logic and 128/spl times/6 bits of ROM plus 2 simple 6b+sign DACs.