High-speed digital and analog performance of low-noise integrated MSM-HEMT photoreceivers

The digital and analog performance of high-speed, monolithically integrated, low-noise metal-semiconductor-metal MSM-HEMT photoreceivers is reported. The MSM photodetectors were vertically integrated with the HEMT´s using a stacked layer structure, with the HEMT layers beneath the MSM layers. The photoreceivers were implemented using a HEMT-based low-noise three-stage transimpedance amplifier. The amplifier transimpedance was 803 /spl Omega/, and the photoreceivers exhibited -3 dB bandwidths up to 7.2 GHz. Analog noise performance was characterized, and average input-referred noise current spectral densities of 6.5 and 7.3 pA/Hz¹2 / were found for receivers with 1and 1.5-μm MSM inter-electrode spacings, respectively. The digital performance of the photoreceivers was examined at bit rates up to 10 Gb/s, and open eye patterns obtained. The measured sensitivity for a bit-error rate of 10/sup -9/ was found to be -16.9 and -13.1 dBm at 5 and 8 Gb/s, respectively, for photoreceivers with a 1.5 μm inter-electrode spacing, and -10.7 dBm at 10 Gb/s for photoreceivers with a 1-μm inter-electrode spacing. To the authors´ knowledge, this is the first report of multigigabit measured sensitivities of MSM-HEMT photoreceivers on InP substrates.