Optically clocked switched-emitter-follower THA in a photonic SiGe BiCMOS technology

In this paper a novel opto-electronic Track-and-Hold Amplifier (OE-THA) is presented. The OE-THA can be used as a sampler in a photonic analog-to-digital-converter (ADC). It is fabricated in a silicon photonic 250 nm SiGe BiCMOS technology to allow for monolithic integration of photonic and electronic components. The OE-THA chip exhibits a small signal bandwidth of over 65 GHz, a total harmonic distortion below -34 dB up to 75 GHz and a signal-to-noise and distortion ratio (SINAD) of over 35 dB (5.5 effective bits, ENOB) up to 45 GHz. The measured resolution bandwidth products result in a corresponding equivalent jitter of below 80 fs rms from 20 to 70 GHz. The best equivalent jitter is achieved at 41 GHz with a value of 55.8 fs rms. This is enabled by using a low-jitter optical pulse train, generated by a Mode-Locked-Laser (MLL), as an optical sampling clock. The circuit integrates all optical and electronic components besides the MLL. It draws 110 mA operated from a supply voltage of -4.6 V and occupies a silicon area of only 0.59 mm².