Microwave Photonic ICs for 25 Gb/s Optical Link Based on SiGe BiCMOS Technology

The design, simulation and experimental results of the integrated optical and electronic components for 25 Gb/s microwave photonic link based on a 0.25 µm SiGe:C BiCMOS technology process are presented. A symmetrical depletion-type Mach-Zehnder modulator (MZM) and driver amplifier are intended for electro-optical (E/O) integrated transmitters. The optical divider and combiner of MZM are designed based on the self-imaging theory and then simulated with EM software. In order to verify the correctness of the theory and material properties used in the simulation, a short test (prototype) MZM of 1.9 mm length is produced and measured. It shows an extinction ratio of 19 dB and half-wave voltage-length product of Vπ ∙ L = ~1.5 V·cm. Based on these results, the construction of the segmented modulator with several driver amplifier units is defined. The designed driver amplifier unit provides a bandwidth of more than 30 GHz, saturated output power of 6 dBm (output voltage of Vpp = 1.26 V), and matching better than −15 dB up to 35 GHz; it dissipates 170 mW of power and occupies an area of 0.4 × 0.38 mm2. The optical-electrical (O/E) receiver consists of a Ge-photodiode, transimpedance amplifier (TIA), and passive optical structures that are integrated on a single chip. The measured O/E 3 dB analog bandwidth of the integrated receiver is 22 GHz, and output matching is better than −15 dB up to 30 GHz, which makes the receiver suitable for 25 Gb/s links with intensity modulation. The receiver operates at 1.55 μm wavelength, uses 2.5 V and 3.3 V power supplies, dissipates 160 mW of power, and occupies an area of 1.46 × 0.85 mm2.