This thesis investigates integrated timing and readout architectures for high-channel-density detection systems, with emphasis on free-running oscillators as compact, continuously available time references. The work addresses the joint design of detector front ends, reference distribution, local time sampling, digitization, calibration, and hierarchical readout under strict constraints on area, power, and routing. It first discusses the timing requirements of silicon pixel detectors and the advantages of monolithic and SiGe BiCMOS technologies for mixed-signal readout. Three architectures are then developed. The first is a multichannel Time-to-Digital Converter for a LiDAR prototype, based on a shared ring oscillator, local fine sampling, coarse counting, and phase-distribution networks. The second is an asynchronous hierarchical readout scheme for the 100 µPET monolithic pixel sensor, organized into quadrants, superpixels, and supercolumns. The third is a picosecond TDC using analog sampling of interpolated oscillator phases and phase reconstruction with calibration of non-uniform time bins for dense detector arrays.