Thermometer code

[Lizwi]

Why is output code of a delay line Time to Digital converter called thermometer code and why does it need to be ecoded to binary because to me it is a binary number?

 

[Delta Prime]

Because that is the fundamentals of DAC architecture.
You ever heard of... Lord Kelvin?

 

[Harald Kapp]

A thermometer code can be used to minimize glitches during switching, see the explanation here.