High-speed mesa type SAGCM avalanche photodiodes for 2.5 Gb s-1 optical receivers have been realized for the first time. The device is designed by dimensional analysis based on the electric field distribution in a multiplication layer and a charge plate layer. Very low dark current and high gain are obtained with an active region of 30 mum diameter. From the 1.55 mum wavelength 2.488 Gb s-1 transmission experiment, sensitivity of -33.6 dBm is measured using pseudorandom (2(23) - 1) NRZ patterns.