Mos varactor and voltage-controlled oscillator using the same
A technology of voltage-controlled oscillators and varactors, applied in power oscillators, electrical components, etc., can solve the problem of difficulty in determining the voltage of capacitance changes, achieve small capacitance changes, small changes in oscillation frequency, and reduce the number and size of components Effect
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no. 1 example
[0033] The first embodiment of the present invention relates to the construction of the MOS varactor used in the voltage controlled oscillator according to the present invention.
[0034] figure 1 (A) to 1(C) schematically show the MOS varactor and its equivalent circuit according to the first embodiment of the present invention. figure 1 (A) shows the first configuration in which one end of the resistor is connected to the base terminal of the MOS transistor, and the other end of the resistor is grounded. figure 1 (B) shows a second configuration in which one end of the capacitor is connected to the base terminal of the MOS transistor, and the other end of the capacitor is grounded. figure 1 (C) shows a third configuration in which one end of a resistor and a capacitor is connected to the base terminal of the MOS transistor, a bias voltage is applied to the other end of the resistor, and the other end of the capacitor is grounded.
[0035] First, like figure 1 As shown in (...
no. 2 example
[0044] image 3 It is a circuit diagram schematically showing the configuration of a voltage controlled oscillator according to the second embodiment of the present invention. The voltage-controlled oscillator according to this embodiment is a MOS varactor, and the MOS varactor according to the first embodiment of the present invention is used. Here, the figure 1 The third configuration shown in (C).
[0045] As in image 3 As shown in, even in the voltage-controlled oscillator according to this embodiment, the Figure 6 In the same manner as in the prior art voltage-controlled oscillator shown in, the source and drain of each of the first and second MOS transistors 5a and 6a are short-circuited. In addition, a variable capacitive element using electrostatic capacitance between the source terminal and the gate terminal or between the drain terminal and the gate terminal of each of the first and second MOS transistors 5a and 6a is used. In particular, the voltage-controlled oscilla...
no. 3 example
[0049] FIG. 4 is a circuit diagram schematically showing a voltage controlled oscillator according to a third embodiment of the present invention. The voltage controlled oscillator according to this embodiment is an oscillator circuit including an amplifier including an inverter 2 and a feedback resistor 1, a crystal vibrator 3, and a load capacitor forming a feedback circuit. As the load capacitor, the first DC blocking capacitor 8, including figure 1 The variable capacitor of the MOS transistor 6b and the second DC blocking capacitor 9 of the third configuration shown in (C).
[0050] According to this configuration, the phase difference between the gate terminal and the source / drain terminals of the MOS transistor 6b is 180°. Therefore, the capacitance value of the MOS varactor becomes equivalent to approximately twice the capacitance value due to the mirror effect.
PUM
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