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

Two modulator drivers in 0.25 μm 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 12.3 mm2. 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 0.68 W but a high gain of S21=37 dB and delivers an inverted as well as a non-inverted output data signal between 0 V and 2.5 V (5 Vpp differential). The driver circuit is supplied with 2.5 V and at the output stage with 3.5 V. 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 50 mVpp. A second adapted driver is supplied with 2.5 V and 4.2 V, consumes 0.87 W and delivers a differential data signal with 5.6 Vpp having a gain of S21=40 dB. The fully integrated modulator achieved at an optical wavelength of 1540 nm and 10 Gb/s data rate an extinction ratio of 3.3 dB for a 1 mm long modulator (VπLπ≈2 V cm) with driver variant 1 and 8.4 dB for a 2 mm long modulator with driver variant 2.