| 摘要 |
A frequency synthesizer is provided to have nearly zero variation according to temperature variation of a PLL(Phase Locked Loop) loop bandwidth. A frequency synthesizer uses a phase locked loop(PLL), and includes a VOC(Voltage-Controlled Oscillator) (10), a 1/N divider(20), a temperature controlled crystal oscillator(30), a phase detector(50), a charge pump(60) and a loop filter(70). The charge pump designs temperature variation of a charge pump current in order to have nearly zero variation of the loop bandwidth according to the temperature variation. |
