A sampling clock generating circuit and an analog to digital converter includes a variable resistance circuit, and a NOT-gate type circuit, where an input end of the NOT-gate type circuit receives a pulse signal whose period is T; a power supply terminal of the NOT-gate type circuit is connected to a power supply; a ground terminal of the NOT-gate type circuit is connected to one end of the variable resistance circuit; and the other end of the variable resistance circuit is grounded; the NOT-gate type circuit is configured to: when the pulse signal is a high level, output a low level; and when the pulse signal is a low level, output a high level.