This paper will describe two 30K-gate chips which have been designed and fabricated to transmit and receive CEFT4 and STM-1 signals at 140 Mbiti sec and 156 Mbitisec data rate operations for SDHiSONET 2.5 Gbitisec transmission systems. A mixed full custom and standard cell design technique has been demonstrated to be very effective in providing short design intervals and attractive costs for high speed, low power systems.