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Positive-bias BE transistor variable capacitance circuit

A junction transistor and transistor technology, which is applied in the field of forward-biased BE junction transistor varactor circuits, can solve the problems of difficult to achieve wide tuning, difficult design and fabrication, and complex structure.

Inactive Publication Date: 2016-11-16
SOUTHWEST JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, using a BE junction as a varactor has a small capacitance value, and it is usually difficult for a single varactor to achieve wide tuning in the microwave low-frequency range. Therefore, in a VCO, multiple varactors are often used to form an array to achieve wide tuning, and its structure is complex. , there are certain difficulties in designing and making

Method used

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  • Positive-bias BE transistor variable capacitance circuit
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  • Positive-bias BE transistor variable capacitance circuit

Examples

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Effect test

Embodiment 1

[0045] This embodiment takes forward-biased BE junction transistor varactor circuit as an example for illustration

[0046] like figure 1As shown, the forward-biased BE junction transistor varactor circuit in this example includes a bias voltage port 1, a straight-through device 2, a current-limiting resistor 3, a first capacitor 4, a transistor 5, a second capacitor 6, a direct-current limiter 7 and application port 8. In this example, the transistor 5 adopts a BJT transistor, the direct device 2 is an inductive structure with a large inductance value, and the direct limiter 7 is a capacitive structure with a large capacitance value. In this example, the positive pole of the bias voltage is connected to the direct device 2, and the negative pole is grounded. The straight-through device 2, the current-limiting resistor 3, the first capacitor 4, and the direct-current limiter 7 are sequentially connected in series. The first capacitor 4 is connected to the base of the transi...

Embodiment 2

[0048] Such as figure 1 As shown, the transistor in this example is an HBT transistor, and the other structures are the same as those in Embodiment 1, and will not be repeated here.

[0049] image 3 This example shows the relationship between the bias voltage and capacitance change, from which it can be seen that when the frequency is 2GHz and the bias voltage changes from 0V to 10V, the port capacitance changes from 0.19pF to 7.1pF.

Embodiment 3

[0051] Such as figure 1 As shown, the transistor in this example is an HBT transistor, and the first capacitor 4 is short-circuited. Other structures are the same as those in Embodiment 1, and will not be repeated here.

[0052] Figure 4 The graph of the relationship between the bias voltage and the capacitance change in this example shows that when the frequency is 2GHz and the bias voltage changes from 0V to 10V, the port capacitance changes from 0.11pF to 360pF.

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Abstract

The invention discloses a positive-bias BE transistor variable capacitance circuit. A bias voltage anode is connected to a straight device, and a bias voltage cathode is grounded; the straight device, a current-limiting resistor, a first capacitor and a straight-limiting device are in series connection in sequence; a collector electrode and an emitting electrode of a transistor are grounded, and a base electrode of the transistor is connected between the current-limiting resistor and the first resistor; one end of a second capacitor is grounded, and the other end of the second capacitor is connected between the first capacitor and the straight-limiting device; and the other end of the straight-limiting device is connected to an application port. The circuit disclosed by the invention is simple in structure and low in cost, has the characteristics of large capacitance ratio and broad tuning, and effectively solves the problem that a single transistor variable capacitance structure is difficult to realize broad tuning in microwave low-frequency stage MMIC. The variable capacitance structure of the circuit can be used for various transistors, the bias voltage, variable capacitance range, capacitance value and capacitance ratio of the variable capacitance structure can be adjusted in a wide range, the implementation of an MMIC technology is facilitated, and the circuit has extremely high practical application value.

Description

technical field [0001] The invention belongs to the field of microwave technology and microwave circuits, and in particular relates to a novel forward-biased BE junction transistor varactor circuit Background technique [0002] Varactor circuits are widely used in various electronic and microwave devices to achieve electronic tuning and increase the operating bandwidth of the device. In the microwave field, varactor circuits can be applied to filters, amplifiers, phase shifters, and oscillators. Among them, due to the inherent narrow-frequency characteristics of their resonant circuits, oscillators become the most urgently tuned devices in practical applications, and they are also varactors. The main application device of the circuit. With the increasing miniaturization and low power requirements of radio frequency circuits, and the increasing development of modern communication technology, the voltage-controlled oscillator (VCO) designed and manufactured using the monolith...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L29/93
CPCH01L29/93
Inventor 熊祥正薛力源廖成高明均罗杰郭晓东
Owner SOUTHWEST JIAOTONG UNIV