| 摘要 |
PURPOSE: A reference frequency generation circuit of a PLL(Phase Locked Loop) for cordless phone is provided to reduce manufacturing costs by using a variable resistance to control a reference frequency of the PLL. CONSTITUTION: A reference frequency generation circuit of a PLL for cordless phone includes a crystal oscillator(28-1), a frequency control portion(28-2), and a temperature compensation circuit(28-3). The crystal oscillator(28-1) is connected to a frequency input terminal of a PLL IC(19). The frequency control portion(28-2) includes fixed capacitors(C11,C12) and a variable resistance(VR11) which are connected in parallel to the crystal oscillator(28-1). The temperature compensation circuit(28-3) includes capacitors(C13,C14) and a resistance(R11) which are connected in parallel to the crystal oscillator(28-1).
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