## 1 Introduction  
Multi-Gb/s serial data links are largely deployed in high energy physics (HEP) environments to exchange data between on-detector readout modules and off-site processing electronics. Luminosity and sensors' granularity growth foreseen for future HEP experiments will lead to a tremendous increase in data volumes and radiation exposures [1]. State-of-the-art radiation-tolerant optical links have been developed in the framework of versatile link (VL) and gigabit transceiver (GBT) projects and are now deployed inside the Large Hadron Collider (LHC) experiments at CERN [2; 3]. They are currently based on both single-mode edge-emitting lasers (EELs) and multi-mode vertical cavity surface emittinglasers (VCSELs) [4], which are directly modulated by means of radiation-hard application-specific integrated circuits (ASICs) [5]. Laser diode-based technologies however suffer from radiation-induced degradation caused by displacement damage. In the next-generation HEP apparatus, particle fluences will become too high (\(\approx 10^{16}\)cm\({}^{-2}\) 1 MeV neutron equivalent) to guarantee VCSELs' operation in the innermost detector layers, and suitable alternatives need to be investigated [6]. In the last few decades, silicon photonics (SiPh) has attracted interest as a viable technology for the realization of power-efficient short-reach optical interconnects. The low-cost, high-yield, and complementary metal oxide semiconductor (CMOS) fabrication processes along with the possibility to integrate different optical functionalities on a single chip allowed it to rapidly become the workhorse of datacom businesses [7]. A similar traction is gradually rising also inside the HEP community since silicon (Si) has already been proven to be an excellent radiation-tolerant material [8]. Moreover, the technological compatibility with electronics opens up new levels of integration at the detector-level, which can alleviate material budget constraints [9]. Much effort has been focused on verifying whether SiPh-based data links can tolerate the harsh conditions typical of HEP experiments. SiPh devices are relatively insensitive to neutron radiation, but they show strong degradation under ionizing X-rays exposure [10]. It was proven that the X-ray-induced impairments can be moved beyond the MGy-level by following some radiation-hardening-by-design (RHBD) techniques [11] or by periodically modifying the driving conditions [12]. Given the recent technology readiness level (TRL) boost, SiPh modulators are starting to become almost as commercial off-the-shelf (COTS) components [13]. Many foundries already provide design kits and layout cells of photonic components that ever more frequently lead to modulation performances up to 50 Gb/s [14]. Nevertheless, equally high-speed and radiation-resistant ASICs are needed to interface these photonic devices with the front-end electronics and make the complete readout units fit into compact modules. From a system-level viewpoint, the best achievement would be the realization of an electronic circuit that is capable of driving a broad variety of SiPh devices, mimicking the GBT driving flexibility for the laser diode case [15]. SiPh-based wavelength division multiplexing (WDM) schemes applied to HEP scenarios are currently under development, and the exploitation of general-purpose drivers could indeed help to attain high aggregate bandwidth readout systems [16]. In this work, we will show that small architectural changes to conventional CMOS drivers for SiPh devices can enable multi-Gb/s transmission on both lumped-element Mach-Zehnder modulators (MZMs) and ring modulators (RMs), at least for relatively low bandwidths compared to datacom frameworks, but still of interest for HEP applications. This paper extends the contribution in [17] in terms of conceptual modeling and experimental results, evaluating the operation of a full-custom CMOS driver with different classes of SiPh modulators. Section 2 provides a background on SiPh modulators and traditional driver circuits.