Comparator circuit, comparator, level sensing circuit and threshold voltage setting method

In a comparing circuit, an input signal switching circuit has a first input terminal, a second input terminal, a first output terminal and a second output terminal. The input signal switching circuit is configured to receive a first input signal inputted to the first input terminal and a second input signal inputted to the second input terminal. The input signal switching circuit is also configured to output the first input signal to switchably one of the first and second output terminals and the second input signal to other thereof in accordance with a switching signal. A comparator has a reverse input terminal and a non-reverse input terminal and configured to receive through the reverse input terminal a first signal outputted from the first output terminal, and receive through the non-reverse input terminal a second signal outputted from the second output terminal.