Patent ID: 8645742

Claim:
A semiconductor device that operates according to a certain operation clock, comprising: a serial communication interface that performs serial communication with outside, according to a unit transfer time based on the operation clock, wherein the serial communication interface includes: a baud rate generator that generates a basic clock for counting the operation clock to define the unit transfer time, based on a result of the count; a transmission/reception controller that controls transmission and reception according to the basic clock generated by the baud rate generator; and a bit rate modulator capable of realizing a desired bit rate by partially masking supply of the operation clock to the baud rate generator, according to preset information, and wherein the bit rate modulator includes: a first counter that counts the operation clock; a weight reversing circuit that reverses a weight for output bits of the first counter; a first register that allows information for determining a duty of the basic clock to be set; a first comparator that compares an output of the weight reversing circuit with an output of the first register; and a logic gate that partially masks the supply of the operation clock to the baud rate generator by performing logical operation between a result of comparison by the comparator and the operation clock.