10 Gb/s 5 Vpp AND 5.6 Vpp drivers implemented together with a monolithically integrated silicon modulator in 0.25 μm SiGe:C BiCMOS

Abstract

Two modulator drivers in 0.25μm SiGe:C BiCMOS, which are integrated each together with a Mach–Zehnder modulator for electro-optical modulation (optical C-band) are presented. The fully integrated modulator occupies an area of 12.3mm2. Carrier depletion in reverse biased pn junctions is used to adjust the refractive index in both arms of the Mach–Zehnder modulator (dual-drive configuration). The first integrated driver has a low power consumption of 0.68W but a high gain of S21=37dB and delivers an inverted as well as a non-inverted output data signal between 0V and 2.5V (5Vpp differential). The driver circuit is supplied with 2.5V and at the output stage with 3.5V. Bit-error-ratio (BER) measurements with a pseudo-random-bit-sequence (PRBS 231−1) resulted in a BER better than 10−12 for input voltage differences down to 50mVpp. A second adapted driver is supplied with 2.5V and 4.2V, consumes 0.87W and delivers a differential data signal with 5.6Vpp having a gain of S21=40dB. The fully integrated modulator achieved at an optical wavelength of 1540nm and 10Gb/s data rate an extinction ratio of 3.3dB for a 1mm long modulator (VπLπ≈2Vcm) with driver variant 1 and 8.4dB for a 2mm long modulator with driver variant 2.