A frequency detection apparatus and method for generating a stable clock signal synchronized with an input signal and a signal boost filter used in the frequency detection apparatus and method, the frequency detection apparatus includes a signal boost filter filtering out the high frequency component of an input signal and boosting the high frequency component, and a frequency detector receiving an input signal with the boosted high frequency component and a clock signal, detecting a frequency difference between the input signal and the clock signal, and producing a control voltage corresponding to the frequency difference. Accordingly, even when there is a big difference between the frequency of the input signal and an oscillating frequency, a frequency error can be stably detected. Thus, a stable clock signal can be obtained.