Patent ID: 8311153

Claim:
A data receiving apparatus for receiving command data encoded by using a combination of high-level periods during which there is radio wave and low-level periods during which there is no radio wave, said data receiving apparatus comprising: a receiving circuit including a differential amplifier circuit receiving said command data through an antenna, and a demodulator outputting a reproduced signal corresponding to said command data in response to an output of said differential amplifier; and an offset adjustment switch circuit judging a logic level of said reproduced signal in said low level periods of said command data using a plurality of logic circuits while said receiving circuit receives said command data, and generates offset switch signals based on said logic level of said reproduced signal in said low level periods, wherein said differential amplifier circuit includes an offset control section adjusting an offset value of said differential amplifier circuit in response to said offset switch signals, wherein said plurality of logic circuits includes: a timing signal generator that generates a plurality of timing signals, wherein each of said plurality of timing signals is generated at a different time; a plurality of data latches that each latch said reproduced signal in response to one of said plurality of timing signals; an offset determination unit that generates an offset determination signal in response to output signals received from said plurality of data latches; and an offset switch signal control circuit that receives said offset determination signal to generate said offset switch signals.