A Wide Input-Range, Low-Power and Highly Flexible 18 Bit Time-to-Digital Converter with Compact Differential Circuit Topology

This paper presents a wide-dynamic-range high-resolution time-domain converter concept tailored for low-power sensor interfaces. The unique system structure applies different techniques to reduce circuit complexity, power consumption, and noise sensitivity. A multi-cycle concept, which allows a virtual delay line extension, is applied to achieve high resolution down to 1 ns. At the same time, it expands the dynamic range drastically up to 2.35 ms. Moreover, individually tunable delay elements in the range of 1 ns to 12 ns allow on the one hand on-demand flexible operation in a low- or high-resolution mode for smart sensing applications and flexible power control. On the other hand, delay stage mismatch calibration. The concept of this paper is evaluated through both simulation and hardware by a custom-designed PCB using commercially available components. An HDL state machine operates as control logic on a generic FPGA. The presented concept is highly suitable for on-chip integration.