VCXO: 电压控制震荡器

A VCXO (Voltage Controlled Crystal Oscillator) is a crystal oscillator the output frequency of which is controlled by adding an external control voltage via a frequency control input on a variable capacitance component such as a varactor diode connected in parallel to a load capacitance (CL). Epson VCXOs are divided into two types according to Voltage-Frequency (V-F) characteristic slopes depending on the AFC (Automatic Frequency Control) input configuration of the VCXO. One is a VCXO with a positive V-F slope and the other is a VCXO with a negative V-F slope. Please note that the input voltage of a control circuit will vary according to the individual type, as shown in Figs. 3 and 4. Epson's VCXOs are capable of either, depending on the customer's preference. Epson's VCXOs have been increasingly used for broader applications such as slave oscillators in phased-lock loops, or frequency modulators. Among the above types, a VCXO combined with a TCXO is called a VC-TCXO , respectively. These components have the merit of delicately controlling their output frequency electrically.