Patent ID: 7475319

Claim:
A threshold voltage control apparatus that controls a threshold voltage for a level comparing section that detects a logic pattern of an input signal by comparing a level of the input signal with the threshold voltage, comprising: a plurality of timing generators that generate periodic signals each with different phase and each with approximately the same period; a shift register section having a plurality of flip-flops in a cascade arrangement that successively propagates data of the logic pattern through the plurality of flip-flops, in response to a first of the periodic signals outputted by a first of the timing generators; a plurality of registers that successively propagate data outputted by one of the flip-flops pre-selected, in one-to-one correspondence with the timing generators except for the first of the timing generators and installed in a cascade arrangement, in response to the periodic signals outputted by the corresponding timing generators; and a threshold voltage generating section that generates the threshold voltage given to the level comparing section, based on data value outputted by the plurality of registers and data value outputted by the plurality of flip-flops.