| 摘要 |
A frequency synthesizer is provided, including a voltage-controlled oscillator (VCO), a frequency prescaler, a divide-by-2.5 circuit, and a selector. The VCO determine the frequency of a first signal according to an input voltage. The frequency prescaler determines the frequency of a second signal to be the frequency of the first signal divided by 3, 3.5, or 4 according to a first selection signal, and the frequency prescaler also determines the frequency of a third signal to be the frequency of the first signal divided by 6, 7, or 8 according to the first selection signal. The divide-by-2.5 circuit generates a fourth signal, wherein the frequency of the fourth signal is the frequency of the first signal divided by 2.5. The selector selects one of the second signal, the third signal, and the fourth signal as a fifth signal according to a second selection signal.
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