Performance of fiber-optic data links using 670-nm cw VCSELs and a monolithic Si photodetector and CMOS preamplifier

Silicon Photo-Receivers

“…The data rate was increased to 622 Mb/s for this wavelength. No measured result for the responsivity was given in [11]. Instead, a three times larger responsivity value of approximately 0.2 A/W for λ = 670 nm was estimated due to the lower penetration depth than for λ = 850 nm.…”

“…A standard BiCMOS technology with a minimum effective channel length of 0.45 µm (corresponding to a drawn or nominal channel length of about 0.6 µm) without any modifications was used [10,11] to exploit a fast photodiode. The buried N + -collector in Fig.…”

“…The dark current of the photodiode was 10 nA for a reverse voltage of 2.5 V at room temperature. In [11] a laser with a wavelength of 670 nm was used for the characterization of the same OEIC as in [10]. The data rate was increased to 622 Mb/s for this wavelength.…”

“…This estimation, however, may be doubtful, because possible destructive interference in the isolation and passivation stack is neglected. The main drawback for the photodiode used in [10,11] was its low responsivity due to the thin epitaxial layer in the SBC-bipolar based BiCMOS process.…”

Investigation of optical interconnect receivers in standard micron and submicron MOS technology

“…The optical receivers described in their articles demonstrated a data rate 8 of 50 Mbit/s and a frequency response 9 of 147 MHz at a supply voltage of 5 V, although the pin photodiodes showed bandwidths of Ϸ300 MHz at a bias of 3 V. A thin p ϩ /n-collector/n ϩ -buried-collector pin photodiode in a BiCMOS process was used together with a MOS amplifier with a rather low responsivity of the photodiode. 10,11 An even lower responsivity of 0.04 A/W was reported for the p ϩ /n-well photodiode of a 1-Gbit/s OEIC in a 0.35-m CMOS technology. 12 It would be possible, to compensate this low receiver sensitivity with a strong VCSEL light source; however, to save VCSEL current and electrical emitter power, it would be desirable to have a higher receiver sensitivity.…”