JPH0629739A - Voltage controlled oscillator - Google Patents

Abstract

PURPOSE:To stabilize the characteristic of a voltage controlled oscillator improve the reproducibility. CONSTITUTION:A transistor TR 1 as an active element for oscillation, a resonance circuit 2, an NPN TR 3, a DC stop capacitor 4, and a resistance element 5 for bias are provided on a semiconductor substrate 7. The junction capacity between the base and the collector of the NPN TR 3 is used as a variable capacity element, and a positive voltage is applied to the collector side and a negative voltage is applied to the base side to change the junction capacity. Thus, the change of the junction capacity is used to control the oscillation frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage controlled oscillator, and more particularly to a microwave band and millimeter wave band voltage controlled oscillator formed as an integrated circuit on a semiconductor substrate.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional voltage controlled oscillator is provided with a transistor 1, a resonance circuit 2, which is an active element for oscillation, and a DC element capacitor 4, on a semiconductor substrate 7, and a bias resistor. Element 5 and variable capacitance diode 6
Was attached externally. Then, the resonance circuit 2 whose approximate oscillation frequency is determined by the length is connected to the base of the transistor 1 so that the base and collector of the transistor 1 and the base
An oscillating circuit is formed by high-frequency feedback with the interelectrode capacitance between the emitters, and the variable capacitance diode 6 is connected to the other end of the resonance circuit 2 via the DC blocking capacitor 4 and the junction of the variable capacitance diode 6 is connected. When the control voltage is applied in the opposite direction, the junction capacitance is changed, and the resonance frequency of the resonance circuit 2 is equivalently changed, thereby changing the oscillation frequency.

[0003]

The variable-capacitance diode used in this conventional voltage-controlled oscillator is extremely difficult to form together with a transistor or the like, which is an active element for oscillation, on a semiconductor substrate. Is externally attached to the outside of a semiconductor substrate on which a transistor, which is an active element for oscillation, is mounted by using a thin film hybrid integrated circuit technology or the like. Therefore, particularly in the microwave and millimeter wave super high frequencies, the influence of the parasitic inductance due to the connecting line cannot be ignored, and the characteristic reproducibility during manufacturing cannot be sufficiently obtained, and the characteristic can be unstable. There were problems such as.

An object of the present invention is to stabilize the characteristics of the voltage controlled oscillator and improve the reproducibility.

[0005]

In order to achieve the above object, according to the present invention, an active element for oscillation, a resonance circuit, a DC blocking capacitor, a variable capacitance element and a resistance element for bias are interconnected on a semiconductor substrate. The voltage controlled oscillator is configured by connecting a variable capacitance element to a base and an emitter of a transistor.

In order to achieve the above object, the present invention provides a voltage controlled oscillator in which an active element for oscillation, a resonance circuit, a DC blocking capacitor, a variable capacitance element and a resistance element for bias are interconnected on a semiconductor substrate. , A variable capacitance element is connected to the base and collector of the transistor.

[0007]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a voltage controlled oscillator according to an embodiment of the present invention. In FIG. 1, on the semiconductor substrate 7,
Transistor 1 which is an active element for oscillation, resonance circuit 2, N
A PN transistor 3, a DC blocking capacitor 4, and a bias resistance element 5 are provided. The junction capacitance between the base and collector of the NPN transistor 3 is used as the variable capacitance element, and a positive voltage is applied to the collector side and a negative voltage is applied to the base side to change the junction capacitance. FIG. 2 shows an example of the logarithm of the junction capacitance between the base and the collector and the voltage between the base and the collector. In this way, the oscillation frequency can be controlled by utilizing the change in the junction capacitance. In the present embodiment, the base and the emitter are short-circuited to make them equipotential. However, it is also possible to short the base and the collector and use the junction capacitance between the base and the emitter.

[0009]

Since the present invention is constructed as described above, it is possible to eliminate the influence of the parasitic inductance due to the connecting line which occurs when the variable capacitance element is externally attached, and the microwave band and the millimeter wave band can be eliminated. Even at super high frequencies of
The effect that the characteristics are stable and the reproducibility is good can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a voltage controlled oscillator according to an embodiment of the present invention.

FIG. 2 is a diagram showing characteristics of the variable capacitance element of the voltage controlled oscillator according to the embodiment of the present invention.

FIG. 3 is a circuit diagram of a conventional voltage controlled oscillator.

[Explanation of symbols]

 1 Transistor 2 Resonant Circuit 3 NPN Transistor 4 DC Blocking Capacitor 5 Bias Resistor

Claims (2)

[Claims] 1. A voltage controlled oscillator in which an active element for oscillation, a resonance circuit, a DC blocking capacitor, a variable capacitance element and a resistance element for bias are interconnected on a semiconductor substrate, the variable capacitance element connecting a base and an emitter of a transistor. A voltage-controlled oscillator characterized by being configured by: 2. A voltage controlled oscillator in which an active element for oscillation, a resonance circuit, a DC blocking capacitor, a variable capacitance element and a resistance element for bias are interconnected on a semiconductor substrate, the variable capacitance element connecting the base and collector of a transistor. A voltage-controlled oscillator characterized by being configured by: