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调频范围是压控振荡器的一个重要的性能指标,当调频范围增大时,振荡器的振幅会随着频率的不同而改变。为了保证压控振荡器在调频范围内振幅恒定,提出了一种新型的自动振幅控制的电路结构。自动振幅控制电路由峰值检测、比较器和低通滤波器几部分构成,自动振幅控制电路与压控振荡器组成的反馈环路控制压控振荡器的输出恒定。电路采用标准的0.35μm CM O S工艺流片并进行测试。测试结果表明:压控振荡器的调频范围为18.2MH z~24.3MH z,达到了28.7%,自动振幅控制电路保证压控振荡器的振幅变化仅为8.7%。
FM range is a VCO important performance indicators, when the FM range increases, the oscillator amplitude will vary with the frequency change. In order to ensure the VCO amplitude constant in the FM range, a new type of automatic amplitude control circuit structure is proposed. Automatic amplitude control circuit consists of peak detection, comparator and low-pass filter several parts, automatic amplitude control circuit and voltage-controlled oscillator feedback loop control voltage-controlled oscillator output constant. The circuit uses a standard 0.35μm CM O S process chip and tested. The test results show that the VCO frequency range is 18.2MH z ~ 24.3MH z, reaching 28.7%. The automatic amplitude control circuit ensures that the VCO amplitude changes only 8.7%.