We have systematically studied the transmission of electrical signals along several 2-strip Resistive Plate Chambers (RPCs) in the frequency range f = 0.1 − 3.5GHz. Such a range was chosen to fully cover the bandwidth associated to the very short rise-times of signals originated in RPCs used for sub-100ps timing applications. This work conveys experimental evidence of the dominant role of modal dispersion in counters built at the 1 meter scale, a fact that results in large cross-talk levels and strong signal shaping. It is shown that modal dispersion appears in RPCs due to the intrinsic unbalance between the capacitive and the inductive coupling Cm/Co = Lm/Lo. A practical way to restore this symmetry has been introduced (hereafter 'electrostatic compensation'), allowing for a cross-talk suppression factor of around ×12 and a rise-time reduction by 200ps. Under conditions of compensation the signal transmission is only limited by dielectric losses, yielding a length-dependent cutoff frequency of around 1GHz per 2 meter for typical float glass -based RPCs (tan δ| glass = 0.025 ± 0.005).It is further shown that 'electrostatic compensation' can be achieved for an arbitrary number of strips as long as the nature of the coupling is 'short-range', that is an almost exact assumption for typical strip-line RPCs. Evidence for deviations from the dominant TEM propagation mode has been observed, although they seem to have negligible influence in practical signal observables. This work extends the bandwidth of previous studies by a factor of almost ×20.

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STiC is a mixed-mode Application Specific Integrated Circuit (ASIC) for Silicon Photomultiplier (SiPM) readout with very high timing resolution. It is designed for the Timeof-Flight (ToF) measurement in Positron Emission Tomography (PET) and in high energy physics experiments. STiC is dedicated particularly to the EndoTOFPET-US project, which is developing and building a multi-modal instrument combing ToFPET and ultrasound endoscopy for the development of new biomarkers for pancreas and prostate oncology. A 64-channel prototype (STiC v3) has been developed and produced in 0.18µm UMC CMOS technology. A fully differential analog front-end has been developed to suppress the common-mode noise from both the on-chip digital part and the outer sources, while it allows for both differential and single-ended readout connection schemes with SiPM. A digital-to-analog converter on the input stage tunes the SiPM bias voltage with a range of ∼ 900 mV, providing the possibility to compensate the variation on the breakdown voltage of the connected SiPMs. A linearized time-over-threshold method has been implemented to provide better energy resolution than the conventional ToT method. The time and energy information are converted into two time stamps, which are digitized by a build-in TDC with time binning of 50.2 ps. A dedicated digital part has been developed for chip configuration with a Serial Peripheral Interface and for data transmission to an external Data Acquisition System using a 160 MBit/s LVDS serial link with 8/10-bit encoding. Measurements have shown a time jitter < 20 ps on the analog front-end and a time jitter of ∼ 37 ps on the TDC and digital part. A Coincidence Time Resolution of ∼ 214 ps FWHM has been obtained by STiC v3 with 3.1 × 3.1 × 15 mm 2 LYSO:Ce crystals and Hamamatsu MPPCs (S12643-050CN(x)). Here we present the details of the ASIC design, measurement results as well as the 128-channel frontend module for EndoTOFPET-US project.

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