| 摘要 |
PURPOSE: An apparatus and a method for detecting a frequency are provided to detect a frequency with accuracy of n multiplication rate using a reference clock. CONSTITUTION: An apparatus for detecting the frequency of an input signal includes a count value setting unit(10) that sets a reference clock frequency such that the reference clock cycle is calculated in n times of count values, and an A/D converter(20) for sampling an analog input signal by the reference clock cycle to convert the analog signal into digital values having positive and negative signs. The apparatus further has zero crossover detector(30) for detecting a variation in the signs to generate a zero crossover detection signal. The apparatus also includes a calculation processor(40), a counter(50), and a frequency calculator(60). The calculation processor divides two sampling sections having a zero crossover point between the sections, and predicts a section where the zero crossover point is located to calculate the count value of each reference clock. The counter accumulates the calculated count value until a variation in the signs occurs. The frequency calculator divides the count value accumulated in the counter by the value set by the count value setting unit to calculate the frequency of the input signal.
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