Gray-code TDC with improved linearity and scalability for LiDAR applications

This paper presents a TDC architecture based on a gray code oscillator with improved linearity, for FPGA implementations. The proposed architecture introduces manual routing as a method to improve the TDC linearity and precision, by controlling the gray code oscillator Datapath, which also reduces the need for calibration mechanisms. Furthermore, the proposed manual routing procedure improves the performance homogeneity across multiple TDC channels, enabling the use of the same calibration module across multiple channels, if further improved precision is required. The proposed TDC channel uses only 16 FPGA logic resources (considering the Xilinx 7 series platform), making it suitable for applications where a large number of measurement channels are required. To validate the proposed architecture and routing procedure, two channels were integrated with a coarse counter, a FIFO memory and an AXI interface, to assemble the pulse measurement unit. A comparison between the default routing implementation and the proposed manual routing has been performed, shown an improvement of 27% on the overall TDC single-shot precision. The implemented TDC achieved a 380 ps RMS resolution, a maximum DNL of 0.38 LSB and a peak-to-peak INL of 0.69 LSB, corresponding to a 21.7% and 70.4% improvement, respectively, when compared to the default design approach.FCT - Fundação para a Ciência e a Tecnologia(037902

Digitial Readout for Microwave Kinetic Inductance Detectors and Applications in High Time Resolution Astronomy

This dissertation spans two topics relating to optical tonear-infrared astronomical cameras built around Microwave KineticInductance Detectors (MKIDs). The first topic is the development of adigital readout system for 10- to 30-kilopixel arrays of MKIDs. MKIDs aresuperconducting detectors that can detect individual photons with a widerange of wavelengths with high time resolution (\SI{2}{\micro s}) and low energyresolution. The advantage of MKIDs over other low temperature detectors with similar capabilities is that it is relatively straightforward to multiplex MKIDs into largearrays. All the complexity of readout is in room temperature electronics.This work discusses the implementation and programming of theseelectronics.The second part of this work demonstrates the capabilities of the prototypeoptical and near-infrared MKID instrument with observations ofpulsars. Detecting optical pulsations in these objects require high timeresolution and low noise. The discovery of a correlation between thebrightness of optical pulses from the Crab pulsar and the time of arrivalof coincident giant radio pulses is presented. The search for opticalpulses from a millisecond pulsar J0337+1715 is discussed along with a newupper limit on the brightness of its optical pulses