CN204442287U - A kind of high-frequency generator - Google Patents

Abstract

The utility model discloses a high-frequency oscillator, which comprises a transistor amplifier and an LC oscillating circuit. The LC oscillating circuit is a capacitor feedback oscillating circuit. In a series circuit, the base of the transistor amplifier is connected to the ground through an inductor, one of the collectors of the transistor amplifier is connected to the series circuit and then connected to the ground, and the other is connected to the base of the transistor amplifier through a parasitic capacitance, One of the emitters of the transistor amplifier is connected between the first capacitor and the second capacitor, and the other is connected to a constant current source and grounded. In the resonant network of the high-frequency oscillator of the utility model, the parasitic capacitance Cbc is connected in series with C1 and C2, which can effectively increase the oscillation frequency of the oscillator, and not only eliminates the influence of the parasitic capacitance on the high-frequency oscillator to reduce its oscillation frequency, but also fully The use of parasitic capacitance helps to increase the oscillation frequency of the high-frequency oscillator.

Description

a high frequency oscillator

technical field

The utility model relates to an oscillator, in particular to a high-frequency oscillator.

Background technique

With the increasing tension of modern communication frequency bands and the rapid development of microwave communication, the design of high-frequency oscillator circuits has become a hot issue in the field of MMIC (Monolithic Microwave Integrated Circuit). Copitts oscillators are widely used in the design of high-frequency oscillation circuits, as shown in Figure 1, which is a typical Copitts oscillator circuit, but due to the influence of the parasitic capacitance between the collector and the base, the Copitts oscillator in Figure 1 The Colpitts oscillating circuit returns to the ground through the parasitic capacitance Cbc1 all the way, returns to the ground through L1 all the way, and returns to the ground through C11 and C12 all the way, so Cbc1, C11 and C12 in the equivalent resonant circuit are connected in parallel. As shown in Figure 2, it is the resonant network diagram of the Copitts oscillator in Figure 1. It can be seen from Figure 2 that the parasitic capacitance Cbc1 is connected in parallel with C11 and C12. It can be seen that the oscillation frequency of the oscillator will be reduced, resulting in that the oscillation frequency cannot be further increased, thus failing to meet the increasingly higher frequency of microwave communication.

Contents of the invention

In order to solve the problem that the existing Copitts oscillator is affected by parasitic capacitance, resulting in the problem that the oscillation frequency cannot be continuously increased, the utility model proposes a high-frequency oscillator, which can solve the above-mentioned problem.

In order to solve the above-mentioned technical problems, the utility model adopts the following technical solutions to realize:

A high-frequency oscillator, comprising a transistor amplifier and an LC oscillating circuit, the LC oscillating circuit is a capacitive feedback oscillating circuit, the capacitive feedback oscillating circuit includes an inductance and a series connection composed of a first capacitor and a second capacitor connected in series circuit, the base of the transistor amplifier is connected to the ground through an inductor, one of the collectors of the transistor amplifier is connected to the series circuit and then connected to the ground, and the other is connected to the base of the transistor amplifier through a parasitic capacitance One of the emitters of the transistor amplifier is connected between the first capacitor and the second capacitor, and the other is connected to a constant current source and grounded.

Further, the inductor is connected in series with the second resistor and then connected to the ground terminal.

Wherein, the transistor amplifier is an NPN transistor or a PNP transistor.

The utility model also proposes another high-frequency oscillator, including a transistor amplifier and an LC oscillating circuit, the LC oscillating circuit is an inductance feedback oscillating circuit, and the inductance feedback oscillating circuit includes a capacitor and a first inductance, a second A series circuit composed of two inductors connected in series, the base of the transistor amplifier is connected to the ground through a capacitor, one of the collectors of the transistor amplifier is connected to the series circuit and then connected to the ground, and the other is connected to the ground through a parasitic capacitance The base of the transistor amplifier is connected, one of the emitters of the transistor amplifier is connected between the first inductor and the second inductor, and the other is connected to a constant current source and grounded.

Further, the capacitor is also connected in series with a resistor and then connected to the ground terminal.

In addition, the utility model also proposes another high-frequency oscillator, including a field effect tube amplifier and an LC oscillating circuit, the LC oscillating circuit is a capacitive feedback oscillating circuit, and the capacitive feedback oscillating circuit includes an inductor and a A series circuit composed of a capacitor and a second capacitor connected in series, the gate of the field effect tube amplifier is connected to the ground terminal through an inductor, and one of the drains of the field effect tube amplifier is connected to the series circuit and then connected to the ground terminal , the other one is connected to the gate of the field effect tube amplifier after passing through the parasitic capacitance, one of the sources of the field effect tube amplifier is connected between the first capacitor and the second capacitor, and the other is connected to the constant current source back to ground.

Further, the inductor is also connected in series with a resistor and then connected to the ground terminal.

Still further, the field effect transistor amplifier is an NMOS transistor or a PMOS transistor.

The utility model also proposes another high-frequency oscillator, including a field effect tube amplifier and an LC oscillating circuit, the LC oscillating circuit is an inductive feedback oscillating circuit, and the inductive feedback oscillating circuit includes a capacitor and a first inductance 1. A series circuit composed of the second inductance in series, the grid of the field effect tube amplifier is connected to the ground terminal through a capacitor, and one of the drains of the field effect tube amplifier is connected to the ground terminal after being connected to the series circuit. In addition One path is connected to the gate of the FET amplifier after passing through the parasitic capacitance, one path of the source of the FET amplifier is connected between the first inductance and the second inductance, and the other path is connected to a constant current source and grounded .

Further, the capacitor is also connected in series with a resistor and then connected to the ground terminal.

Compared with the prior art, the advantages and positive effects of the utility model are: in the resonant network of the high-frequency oscillator of the utility model, the parasitic capacitance Cbc is connected in series with C1 and C2, and since the capacitor value in series decreases, the It can be seen that the oscillation frequency of the oscillator can be effectively increased, which not only eliminates the influence of parasitic capacitance on reducing the oscillation frequency of the high-frequency oscillator, but also makes full use of the parasitic capacitance to help it increase the oscillation frequency of the high-frequency oscillator.

After reading the detailed description of the embodiments of the utility model in conjunction with the accompanying drawings, other features and advantages of the utility model will become clearer.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are only some embodiments of the utility model, and those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a kind of embodiment circuit schematic diagram of the high-frequency oscillator of prior art;

Fig. 2 is the schematic diagram of the resonant network of the high frequency oscillator in Fig. 1;

Fig. 3 is the circuit principle diagram of the first embodiment of the high-frequency oscillator proposed by the utility model;

Fig. 4 is the schematic diagram of the resonant network of the high-frequency oscillator in Fig. 3;

Fig. 5 is the equivalent replacement circuit schematic diagram of the intermediate frequency oscillator of the first embodiment;

Fig. 6 is the circuit schematic diagram of the second embodiment of the high-frequency oscillator proposed by the utility model;

Fig. 7 is a circuit schematic diagram of the third embodiment of the high-frequency oscillator proposed by the utility model.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Embodiment 1. This embodiment proposes a high-frequency oscillator, as shown in FIG. 3 , including a transistor amplifier Q1 and an LC oscillating circuit, the LC oscillating circuit is a capacitive feedback oscillating circuit, and the capacitive feedback oscillating circuit It includes an inductance L and a series circuit composed of a first capacitor C1 and a second capacitor C2 connected in series, the base of the transistor amplifier Q1 is connected to the ground terminal through the inductance L, and one of the collectors of the transistor amplifier Q1 is connected to the series circuit After the circuit is connected, it is connected to the ground terminal, and the other one is connected to the base of the transistor amplifier Q1 through the parasitic capacitance Cbc, and one of the emitters of the transistor amplifier Q1 is connected between the first capacitor C1 and the second capacitor C2 , the other way is grounded after connecting the constant current source Is. Taking the NPN triode as an example in the transistor amplifier Q1 in Figure 3, the oscillation principle of this oscillator is: Assume that the small signal phase of the base of the NPN transistor Q1 is "﹢", and according to the principle of the direction of the triode, the phase of the collector is "-", the small signal (noise signal) at the collector of the triode flows through the resonant network formed by the inductance L, the parasitic capacitance Cbc, the first capacitance C1, and the second capacitance C2 to generate an oscillation signal of the corresponding frequency. At the same time, the phase of the base signal It can be seen that the phase of the small signal generated after the feedback signal flows through the resonant network is "+", which is positively superimposed on the base signal with the phase of "+", so oscillation occurs. The resonant network of the high-frequency oscillator in this embodiment is shown in Figure 4. It can be seen from Figure 4 that the parasitic capacitance Cbc is connected in series with C1 and C2. It can be seen that the oscillation frequency of the oscillator can be effectively increased.

In order to prevent the transistor amplifier Q1 from being damaged due to excessive oscillating current, the inductance L is connected in series with the second resistor R2 and then connected to the ground terminal. The second resistor R2 is a bias resistor to prevent the current flowing into the base of the transistor amplifier Q1 from being too large. to its damage.

It should be noted that, in addition to using the NPN triode in this embodiment as the transistor amplifier, the PNP triode can also be used as the transistor amplifier, as shown in Figure 5, the resonant network of the high-frequency oscillator described in Figure 5 and The resonant network of the high frequency oscillator in FIG. 3 is the same, as shown in FIG. 4 , and will not be repeated here.

Embodiment 2. This embodiment also proposes another high-frequency oscillator, as shown in FIG. 6 , which includes a transistor amplifier Q1 and an LC oscillating circuit. The LC oscillating circuit is an inductive feedback oscillating circuit, and the inductive feedback The oscillating circuit includes a capacitor C and a series circuit composed of a first inductance L1 and a second inductance L2 connected in series, the base of the transistor amplifier Q1 is connected to the ground terminal through the capacitor C, and one of the collectors of the transistor amplifier Q1 is connected to the After the series circuit is connected, it is connected to the ground terminal, and the other one is connected to the base of the transistor amplifier Q1 through the parasitic capacitance Cbc, and one of the emitters of the transistor amplifier Q1 is connected to the first inductance L1 and the second inductance L2 Between, the other road is connected to the constant current source I0 and then grounded. This embodiment is an inductive three-point high-frequency oscillator, and its resonant principle is similar to that of Embodiment 1, and will not be repeated here. The capacitor is also connected in series with a resistor and then connected to the ground terminal.

Embodiment three, this embodiment proposes another high-frequency oscillator, as shown in Figure 7, including a field effect tube amplifier Q2 and an LC oscillating circuit, the LC oscillating circuit is a capacitive feedback oscillating circuit, and the capacitive feedback The oscillating circuit includes an inductance L and a series circuit composed of a first capacitor C1 and a second capacitor C2 connected in series. Taking the field effect tube amplifier Q2 in FIG. 7 as an example using an NMOS tube, the gate of the field effect tube amplifier Q2 passes The inductance L is connected to the ground terminal, one of the drains of the field effect tube amplifier Q2 is connected to the series circuit and then connected to the ground terminal, and the other one is connected to the gate of the field effect tube amplifier Q2 after passing through the parasitic capacitance Cbc, One of the sources of the FET amplifier Q2 is connected between the first capacitor C1 and the second capacitor C2, and the other is connected to the constant current source Is and grounded. The oscillation principle of this oscillator is as follows: Assume that the small signal phase of the field effect tube amplifier Q2 gate is "+", according to the direction principle of the field effect tube amplifier, the phase of the drain is "-", and the drain of the field effect tube amplifier is "-". The small signal (noise signal) of the small signal (noise signal) flows through the resonant network composed of the inductor L, the parasitic capacitor Cbc, the first capacitor C1, and the second capacitor C2 to generate an oscillation signal of the corresponding frequency. At the same time, it can be seen from the phase of the gate signal that the feedback signal The phase of the small signal generated after flowing through the resonant network is "+", which is positively superimposed with the gate signal of "+", so oscillation occurs. The resonant network of the high-frequency oscillator in this embodiment can also be referred to as shown in FIG. 4. It can be seen from FIG. 4 that the parasitic capacitance Cbc is connected in series with C1 and C2. It can be seen that the oscillation frequency of the oscillator can be effectively increased.

In order to prevent excessive oscillating current from damaging the FET amplifier Q2, the inductance L is connected in series with a resistor R2 and then connected to the ground terminal. The resistor R2 is a bias resistor to prevent excessive current flowing into the grid of the FET amplifier Q2. to its damage.

In addition to the NMOS transistor used in the field effect transistor amplifier Q2 of this embodiment, it can also be realized by using a PMOS transistor.

Of course, the above description is not a limitation of the present utility model, and the present utility model is not limited to the above-mentioned examples. Those of ordinary skill in the art may make changes, modifications, additions or replacements within the essential scope of the present utility model. It should also belong to the protection scope of the present utility model.

Claims (10)

1. A high-frequency oscillator, comprising a transistor amplifier and an LC oscillating circuit, is characterized in that: the LC oscillating circuit is a capacitive feedback oscillating circuit, and the capacitive feedback oscillating circuit includes an inductance and a first capacitance, a second A series circuit composed of capacitors in series, the base of the transistor amplifier is connected to the ground terminal through an inductor, one of the collectors of the transistor amplifier is connected to the series circuit and then connected to the ground terminal, and the other is connected to the ground terminal through a parasitic capacitance. The base of the transistor amplifier is connected, one of the emitters of the transistor amplifier is connected between the first capacitor and the second capacitor, and the other is connected to a constant current source and grounded. 2. The high-frequency oscillator according to claim 1, wherein the inductor is further connected in series with the second resistor and then connected to the ground terminal. 3. The high-frequency oscillator according to claim 1 or 2, characterized in that: the transistor amplifier is an NPN transistor or a PNP transistor. 4. A high-frequency oscillator, comprising a transistor amplifier and an LC oscillating circuit, characterized in that: the LC oscillating circuit is an inductive feedback oscillating circuit, and the inductive feedback oscillating circuit includes a capacitor and a first inductance, a second A series circuit composed of inductors in series, the base of the transistor amplifier is connected to the ground terminal through a capacitor, one of the collectors of the transistor amplifier is connected to the series circuit and then connected to the ground terminal, and the other is connected to the ground terminal through a parasitic capacitance. The base of the transistor amplifier is connected, one of the emitters of the transistor amplifier is connected between the first inductance and the second inductance, and the other is connected to a constant current source and grounded. 5. The high-frequency oscillator according to claim 4, wherein the capacitor is also connected in series with a resistor and then connected to the ground terminal. 6. A high-frequency oscillator, comprising a field effect tube amplifier and an LC oscillating circuit, characterized in that: the LC oscillating circuit is a capacitance feedback oscillation circuit, and the capacitance feedback oscillation circuit includes an inductor and a first capacitor, A series circuit composed of the second capacitor connected in series, the gate of the field effect tube amplifier is connected to the ground terminal through an inductor, one of the drain poles of the field effect tube amplifier is connected to the series circuit and then connected to the ground terminal, and the other circuit is connected to the ground terminal. After passing through the parasitic capacitance, it is connected to the gate of the FET amplifier, one of the sources of the FET amplifier is connected between the first capacitor and the second capacitor, and the other is connected to a constant current source and grounded. 7. The high-frequency oscillator according to claim 6, wherein the inductor is further connected in series with a resistor and then connected to the ground terminal. 8. The high frequency oscillator according to claim 6 or 7, characterized in that: the field effect transistor amplifier is an NMOS transistor or a PMOS transistor. 9. A high-frequency oscillator, comprising a field effect tube amplifier and an LC oscillating circuit, characterized in that: the LC oscillating circuit is an inductive feedback oscillating circuit, and the inductive feedback oscillating circuit includes a capacitor and a first inductance, A series circuit composed of the second inductance in series, the gate of the field effect tube amplifier is connected to the ground terminal through a capacitor, one of the drains of the field effect tube amplifier is connected to the series circuit and then connected to the ground terminal, and the other circuit is connected to the ground terminal. After passing through the parasitic capacitance, it is connected to the gate of the field effect tube amplifier. One of the sources of the field effect tube amplifier is connected between the first inductor and the second inductor, and the other is connected to a constant current source and grounded. 10. The high-frequency oscillator according to claim 9, wherein the capacitor is connected in series with a resistor and then connected to the ground terminal.