Carry Chain used as delay line - Problems with supllying LUT-s with ones and zeros

I don't think you may obtain better resolution based on this simple TDC, all improvements for FPGA based designs I have read about, are based on more complicated structures and processing (wave union, double sampling, vernier methods etc) which I find unjustified effort at list in my case. Instead I am investigating analog interpolators which are quite simple and allow easy achievable high resolution with good linearity. Classical analog interpolator are based on pulse stretching method, you will find lot of examples by simple google search. Another novel method you may see in the attached paper, I find it very interesting and promising, it could be a small add on board with sigma-delta ADC on FPGA if you want to avoid any external ADC or additional microcontroller with embedded ADC...