Variable capacity device

Abstract

This invention relates to a variable condenser device including a condenser set and a condenser circuit of a first transistor bridge-jointing said condenser set, a first variable resistor and a second transistor, in which, said second transistor is coupled to said first transistor and serial to said first variable resistor for feeding back the output signal generated by applying the voltage on the condenser circuit to the first transistor to control the gain of the first transistor by adjusting the first variable resistor.

Description

technical field [0001] The invention relates to a variable capacitance device, in particular to a variable capacitance device which can continuously adjust the capacitance in a wide range. Background technique [0002] Traditional varactors can be completed using MOS process, such as figure 1 The MOS varactor shown has a capacitance tuning ratio of less than 3 and requires a complex mask, which does not meet actual needs. figure 2 It is a diode varactor (Diode varactor) made by CMOS process, and its capacitance tuning ratio is less than 2. Therefore, the capacitance can only be adjusted in a small range, and it is difficult to meet the actual needs. [0003] There are also digitally designed varactors, such as image 3 The digital varactor circuit shown, which consists of a capacitor C F 、C DO～N and switching transistors SO~N, where the switching transistor S O～N respectively control the capacitor C DO～N is connected in parallel to CF, therefore, by controlling the sw...

AI Technical Summary

Problems solved by technology

[0002] Traditional varactors can be completed using MOS process, such as figure 1 The MOS varactor shown has a Capacitance tuning ratio of less than 3 and requires a complex mask, which does not meet actual needs

figure 2 It is a diode varactor (Diode varactor), which is completed using a CMOS process, and its capacitance tuning rate is less than 2. Therefore, the capacitance can only be adjusted in a small range, and it is difficult to meet actual needs.

[0003] There are also digitally designed varactors, such as image 3 The digital varactor circuit shown, which consists of a capacitor C F 、C DO～N and switching transistors SO~N, where the switching transistor S O～N respectively control the capacitor C DO～N is connected in parallel to CF, therefore, by controlling the switching transistor S O～N Whether it is turned on or not, the number of capacitors connected in parallel can be changed, so the effect of adjusting the capacitance can be achieved, and by increasing the capacitor C DO～N The number can greatly increase its capacitance tuning rate. However, this capacitance change can only adjust the capacitance to a specific value, and cannot continuously adjust the capacitance.

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