Correction circuit for improving capacitance and bias characteristics of varactor diode, and equipment using the same
A varactor diode and diode technology, which is applied to electrical components, power oscillators, etc., can solve the difficulty of the nuclear magnetic resonance field measuring instrument to search for the resonance frequency to lock the resonance point, the oscillation frequency of the voltage-controlled oscillator cannot be uniformly changed, and the frequency search circuit cannot Locking resonance points, etc.
Inactive Publication Date: 2016-11-16
NAT INST OF METROLOGY CHINA
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[0007] Secondly, it is precisely because of the nonlinear relationship between the capacitance of the varactor diode and the bias voltage that the oscillation frequency of the voltage-controlled oscillator cannot change uniformly with the bias voltage of the varactor diode. When the oscillation frequency of the voltage-controlled oscillator reaches the resonance frequency , if the oscillation frequency of the voltage-controlled oscillator changes too fast, it will cause the frequency search circuit to be unable to lock the resonance point, making it difficult for the NMR field tester to search for the resonance frequency and lock the resonance point
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[0043] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the application. However, the present application can be implemented in many other ways different from those described here, and those skilled in the art can make similar promotions without violating the connotation of the present application. Therefore, the present application is not limited by the specific implementation disclosed below.
[0044] The application provides a correction circuit for improving the capacitance and bias characteristics of the varactor diode; in addition, the application further provides a voltage-controlled oscillator and a nuclear magnetic resonance field measuring instrument.
[0045] An embodiment corresponding to a correction circuit for improving the capacitance and bias characteristics of a varactor diode is as follows:
[0046] refer to figure 1 -- figure 2 , which shows a correction circuit provided by this embodim...
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The invention discloses a correction circuit for improving capacitance and bias voltage characteristics of a variode. The correction circuit comprises an input end, an output end, a low pass filter, a crystal triode, a first field-effect transistor, a second field-effect transistor, a base resistor and a crystal diode. The crystal diode is used as a switch element. The second field-effect transistor is used for enabling the output voltage of the output end to keep constant when the voltage between the drain electrode and the source electrode of the second field-effect transistor increases. The first field-effect transistor is used for controlling the output voltage value. The second field-effect transistor is used for enabling the output voltage of the output end to increase along with the input voltage in a linear mode when the second field-effect transistor is in a saturated mode. According to the correction circuit, the search frequency of a nuclear magnetic resonance field measurement instrument changes uniformly along with the search voltage, so the nuclear magnetic resonance field measurement instrument can be more accurate in the process of searching for a field to be measured and more reliable in the process of locking the field to be measured. The invention further provides a device using the circuit.
Description
technical field [0001] The present application relates to the technical field of voltage-controlled oscillators, in particular to a correction circuit for improving the capacitance and bias characteristics of a varactor diode. The application also relates to a voltage-controlled oscillator and a nuclear magnetic resonance field measuring instrument. Background technique [0002] A voltage-controlled oscillator (VCO, voltage-controlled oscillator) refers to an oscillating circuit whose output frequency corresponds to the input control voltage. The voltage controlled oscillator is one of the very important basic circuits in integrated circuits, and is widely used in various circuits. The oscillation frequency is one of the main parameters to measure the performance of the voltage-controlled oscillator. The oscillation frequency of the voltage-controlled oscillator is determined by the inductance and capacitance in the resonant circuit. In most cases, a varactor diode is used ...
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IPC IPC(8): H03B5/04H03B5/08
Inventor 韩冰张钟华贺青王少华王永瑞李正坤鲁云峰
Owner NAT INST OF METROLOGY CHINA