JP2012257111A - Active circuit - Google Patents

Abstract

An active circuit for preventing an operation of a second harmonic processing circuit from being hindered and preventing deterioration in operation efficiency is obtained.
In a bias circuit, a filter circuit is connected to an output side of a fundamental wave matching circuit, passes all fundamental wave frequency components and reflects a second harmonic frequency component, and an output of the fundamental wave matching circuit. Connected to the filter circuit 51, connected to the second harmonic absorption circuit 52 and the second harmonic absorption circuit 52, which resonates in parallel at the fundamental frequency and becomes substantially pure resistance to the second harmonic frequency. And a bias voltage supply circuit 53 for supplying a bias voltage.
In the bias circuit 5, the second harmonic frequency component is absorbed without being reflected to the high frequency transistor 2 side, so that the second harmonic processing circuit 3 and the bias circuit 5 do not cause parallel resonance. It is possible to obtain an active circuit that prevents the operation of the wave processing circuit 3 from being hindered and prevents deterioration in operation efficiency.
[Selection] Figure 1

Description

  The present invention relates to an active circuit including a bias circuit, a second harmonic processing circuit, and a fundamental matching circuit in a high-frequency transistor.

  As a conventional active circuit, connected to the drain terminal of a high frequency transistor, connected to the output side of the third harmonic matching circuit and the third harmonic matching circuit that supplies drain bias power and performs impedance matching with the third harmonic And a second harmonic matching circuit that performs impedance matching with respect to the second harmonic, and a fundamental wave matching circuit that is connected to the output side of the second harmonic matching circuit and performs impedance matching with respect to the fundamental. (Patent Document 1 below).

JP 2000-106510 A

Since the conventional active circuit is configured as described above, the second harmonic matching circuit is set to resonate in series with the second harmonic.
In addition, the bias circuit may have a reactance component at the second harmonic.
In this case, in the vicinity of the second harmonic, parallel resonance occurs between the series resonant circuit of the second harmonic matching circuit and the reactance component of the bias circuit, and the impedance viewed from the high frequency transistor is opened.
As a result, there has been a problem that the operation of the second harmonic matching circuit may be hindered and the operation efficiency of the active circuit may be deteriorated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an active circuit that prevents the operation of the harmonic processing circuit from being hindered and prevents the operation efficiency from being deteriorated.

  The active circuit of the present invention is configured such that the fundamental frequency component is completely passed through the bias circuit and the harmonic frequency component is absorbed without being reflected to the high frequency transistor side.

According to the present invention, the bias circuit can have a function basically required as an active circuit by allowing the fundamental frequency component to pass through.
Moreover, in the bias circuit, the harmonic frequency component is absorbed without being reflected to the high-frequency transistor side, so that the harmonic processing circuit and the bias circuit do not cause parallel resonance, and as a result, the operation of the harmonic processing circuit. Therefore, there is an effect that an active circuit can be obtained which prevents the deterioration of the operation efficiency and prevents the deterioration of the operation efficiency.

It is a circuit diagram which shows the active circuit by Embodiment 1 of this invention. It is a circuit diagram which shows the case where parallel resonance is caused by the 2nd harmonic processing circuit and the bias circuit. It is a circuit diagram which shows the active circuit by Embodiment 2 of this invention. It is a circuit diagram which shows the active circuit by Embodiment 3 of this invention. It is a circuit diagram which shows the active circuit by Embodiment 4 of this invention.

Embodiment 1 FIG.
1 is a circuit diagram showing an active circuit according to Embodiment 1 of the present invention.
In FIG. 1, the high frequency transistor 2 is composed of a field effect transistor, and amplifies a high frequency signal from the input terminal 1.

  The second harmonic processing circuit 3 is connected to the drain terminal of the high frequency transistor 2 and controls the impedance with respect to the second harmonic frequency of the fundamental frequency (a frequency twice the fundamental frequency) to an optimum position. The fundamental wave matching circuit 4 controls the impedance with respect to the fundamental frequency to an optimum position.

The bias circuit 5 supplies power to the high frequency transistor 2 and absorbs the fundamental frequency component completely without passing it through the high frequency transistor 2 without reflecting it to the high frequency transistor 2 side.
The capacitor 6 blocks the direct current component, and the fundamental frequency component amplified by the high frequency transistor 2 is output from the output terminal 7.

  In the second harmonic processing circuit 3, the distributed constant line 31 has a length that is ¼ times the wavelength of the second harmonic, and is arranged along the distributed constant line 41 of the fundamental wave matching circuit 4 at a constant interval. One end on the high frequency transistor 2 side is connected to the ground.

  In the fundamental wave matching circuit 4, the distributed constant line 41 is connected to the drain terminal of the high-frequency transistor 2, and one end of the distributed constant line 42 is connected to the output side of the distributed constant line 41 and the other end is open. The distributed constant lines 41 and 42 are set to a line length that realizes a desired impedance.

  In the bias circuit 5, the filter circuit 51 passes all the fundamental frequency components and reflects the second harmonic frequency components. The second harmonic absorption circuit 52 resonates in parallel at the fundamental frequency and becomes substantially pure resistance to the second harmonic frequency. The bias voltage supply circuit 53 supplies a bias voltage.

  In the filter circuit 51, the distributed constant lines 51a to 51d each have a length that is ¼ times the wavelength of the second harmonic. The distributed constant lines 51 a and 51 b are connected in series to the output side of the fundamental wave matching circuit 4. One end of the distributed constant line 51c is connected between the distributed constant lines 51a and 51b, and the other end is opened. The distributed constant line 51d has one end connected to the output side of the distributed constant line 51b and the other end open.

  In the second harmonic absorption circuit 52, the distributed constant line 52a is connected to the node A and has a length that is ¼ times the fundamental wavelength. The radial stub 52b is connected to the node B, the other end is opened, and the length of the radius is 1/4 times the fundamental wavelength. The radial stub 52c is connected to the node B, the other end is opened, and the length of the radius is shorter than ¼ of the second harmonic wavelength. The distributed constant line 52d is connected to the node B and has a length that is ¼ times the wavelength of the second harmonic. Resistance element 52e has one end connected to node B. The distributed constant line 52f is connected to the other end of the resistance element 52e, the other end is opened, and has a length that is 1/4 times the wavelength of the second harmonic wave.

  In the bias voltage supply circuit 53, the capacitor 53a is connected between the distributed constant line 52d and the ground, and the bias voltage terminal 53b is connected between the distributed constant line 52d and the capacitor 53a to supply a bias voltage.

Next, the operation will be described.
The high frequency transistor 2 amplifies the high frequency signal input from the input terminal 1 based on the bias voltage supplied from the bias voltage terminal 53 b of the bias circuit 5.

At this time, the second harmonic processing circuit 3 short-circuits the second harmonic frequency component by the distributed constant line 31 arranged in parallel to the distributed constant line 41, and controls the impedance with respect to the second harmonic frequency to the optimum position.
Further, the fundamental wave matching circuit 4 controls the impedance with respect to the fundamental wave frequency to an optimum position by using the distributed constant lines 41 and 42.
However, in the second harmonic processing circuit 3, not all the second harmonics are absorbed, but the second harmonic is transmitted to the bias circuit 5 while being superimposed on the fundamental wave.

Regarding the bias circuit 5, first, an operation on the fundamental wave will be described.
In the double wave absorption circuit 52, the radius of the radial stub 52b is set to ¼ times the fundamental wave wavelength, so that the node B becomes an electrical short-circuit point. Therefore, the node A, which is the other end of the distributed constant line 52a, becomes an electrical open point. In addition, since the filter circuit 51 passes all of the fundamental wave, the fundamental wave of the high-frequency signal is output from the output terminal 7 without loss.

Next, the operation of the bias circuit 5 with respect to the second harmonic will be described.
The filter circuit 51 reflects the second harmonic wave.

In the second harmonic absorption circuit 52, the radial stub 52b has a radius set to ¼ times the fundamental wave wavelength, and therefore exhibits a slightly inductive reactance at the second harmonic.
On the other hand, since the radial stub 52c adjacent to the radial stub 52b is set to have a radius shorter than ¼ of the second harmonic wavelength, the second harmonic exhibits capacitive reactance.
Therefore, both of them resonate in parallel at the second harmonic frequency.

On the other hand, the node C which is one end of the distributed constant line 52d terminated by the capacitor 53a serves as an electrical open point. In addition, the resistance element 52e functions as a pure resistance at the second harmonic frequency together with the distributed constant line 52f.
Therefore, the second harmonic wave reflected by the filter circuit 51 is absorbed by the resistance element 52e.

Thus, the impedance with respect to the fundamental wave of the second harmonic absorption circuit 52 viewed from the node A is opened by parallel resonance. Therefore, the fundamental wave passes through the filter circuit 51 without loss and is output from the output terminal 7.
On the other hand, since the impedance with respect to the second harmonic of the second harmonic absorption circuit 52 viewed from the node A is the resistance element 52e, the second harmonic is absorbed by the resistance element 52e.

Next, the effect of being able to absorb the second harmonic component by the bias circuit 5 will be described.
FIG. 2 is a circuit diagram showing a case where parallel resonance occurs in the second harmonic processing circuit and the bias circuit.
Since the second harmonic processing circuit 3 is short-circuited at the second harmonic, it can be expressed as a series resonant circuit of an inductor L and a capacitor C that resonate at the second harmonic frequency.
Here, when the bias circuit 5 has a reactance component at the second harmonic frequency, parallel resonance occurs between the series resonance circuit of the second harmonic processing circuit 3 and the reactance component of the bias circuit 5 in the vicinity of the second harmonic frequency. Can be considered.

  On the other hand, in the active circuit shown in FIG. 1, the bias circuit 5 can absorb the second harmonic, and unnecessary resonance with the second harmonic processing circuit 3 can be suppressed.

  According to the first embodiment, the bias circuit 5 absorbs the second harmonic frequency component without reflecting it to the high frequency transistor 2 side, thereby causing parallel resonance between the second harmonic processing circuit 3 and the bias circuit 5. As a result, it is possible to obtain an active circuit that prevents the operation of the second harmonic processing circuit 3 from being hindered and prevents deterioration in operation efficiency.

  Further, the filter circuit 51 and the second harmonic wave absorption circuit 52 can be configured using a distributed constant circuit.

According to the first embodiment, the second harmonic processing circuit 3 is provided, and the bias circuit 5 includes the filter circuit 51 that reflects the second harmonic and the second harmonic absorption circuit 52 that absorbs the second harmonic. .
However, not only the second harmonic but also the one corresponding to the harmonic frequency n (n is an arbitrary natural number of 2 or more) times the fundamental frequency has the same effect.

  Further, according to the first embodiment, the low-pass filter is shown as the filter circuit 51. However, the same effect can be obtained even with the band rejection filter.

Embodiment 2. FIG.
In the first embodiment, unnecessary resonance on the output side of the high frequency transistor 2 is suppressed. However, in the second embodiment, unnecessary resonance on the input side of the high frequency transistor 2 is suppressed.

FIG. 3 is a circuit diagram showing an active circuit according to Embodiment 2 of the present invention.
In FIG. 3, an input terminal 1, a capacitor 8 that blocks a DC component, a bias circuit 9, a fundamental wave matching circuit 10, a second harmonic processing circuit 11, a high-frequency transistor 2, and an output terminal 7 are connected in this order.

In the bias circuit 9, the filter circuit 91 totally passes the fundamental frequency component and reflects the second harmonic frequency component. The second harmonic absorption circuit 92 resonates in parallel at the fundamental frequency and becomes substantially pure resistance to the second harmonic frequency. The bias voltage supply circuit 93 supplies a bias voltage.
The internal configurations of the filter circuit 91, the second harmonic absorption circuit 92, and the bias voltage supply circuit 93 are the same as those in FIG.

  In the fundamental wave matching circuit 10, the distributed constant line 101 is connected to the bias circuit 9 and the gate terminal of the high-frequency transistor 2, and one end of the distributed constant line 102 is connected between the bias circuit 9 and the distributed constant line 41, The other end is open. The distributed constant lines 101 and 102 are set to have a line length that realizes a desired impedance.

  In the second harmonic processing circuit 11, the distributed constant line 111 has a length that is ¼ times the second harmonic wavelength, and is arranged along the distributed constant line 101 of the fundamental wave matching circuit 10 at a constant interval. One end on the high frequency transistor 2 side is connected to the ground.

  According to the second embodiment, since the bias circuit 9, the fundamental wave matching circuit 10, and the second harmonic processing circuit 11 are provided on the input side of the high frequency transistor 2, the second harmonic frequency component is generated in the bias circuit 9. By absorbing without reflecting to the high frequency transistor 2 side, the second harmonic processing circuit 11 and the bias circuit 9 do not cause parallel resonance. As a result, on the input side of the high frequency transistor 2, the second harmonic processing circuit Thus, an active circuit can be obtained in which the obstruction of the operation 11 is prevented and the deterioration of the operation efficiency is prevented.

  Further, the filter circuit 91 and the second harmonic wave absorption circuit 92 can be configured using a distributed constant circuit.

According to the second embodiment, the second harmonic processing circuit 11 is provided, and the bias circuit 9 includes the filter circuit 91 that reflects the second harmonic and the second harmonic absorption circuit 92 that absorbs the second harmonic. .
However, not only the second harmonic but also the one corresponding to the harmonic frequency n (n is an arbitrary natural number of 2 or more) times the fundamental frequency has the same effect.

  Further, according to the second embodiment, the low-pass filter is shown as the filter circuit 91, but the same effect can be obtained even with the band rejection filter.

Embodiment 3 FIG.
In the first embodiment, unnecessary resonance is suppressed only on the output side of the high-frequency transistor 2 and in the second embodiment only on the input side of the high-frequency transistor 2. It is intended to suppress unnecessary resonance on the input side and output side.

4 is a circuit diagram showing an active circuit according to a third embodiment of the present invention.
4, the input side of the high frequency transistor 2 is connected in the order of the input terminal 1, the capacitor 8, the bias circuit 9, the fundamental wave matching circuit 10, the second harmonic processing circuit 11, and the high frequency transistor 2 in the same manner as in FIG. The output side of the high-frequency transistor 2 is connected in the order of the second harmonic processing circuit 3, the fundamental wave matching circuit 4, the bias circuit 5, the capacitor 6 and the output terminal 7 as in FIG.

  According to the third embodiment, the bias circuit 9, the fundamental wave matching circuit 10, and the second harmonic processing circuit 11 are provided on the input side of the high frequency transistor 2, and the second harmonic processing circuit is provided on the output side of the high frequency transistor 2. 3. Since the fundamental wave matching circuit 4 and the bias circuit 5 are provided, it is possible to obtain an active circuit that does not cause parallel resonance on the input side and output side of the high-frequency transistor 2 and prevents deterioration in operating efficiency.

  Although the single-stage amplifier has been described according to the third embodiment, the same effects can be obtained even when applied to a multi-stage amplifier.

Embodiment 4 FIG.
In the first to third embodiments, the bias circuits 5 and 9 are configured by distributed constant circuits and resistance elements. However, in the fourth embodiment, the bias circuits 5 and 9 are lumped constant circuits. It is composed of

5 is a circuit diagram showing an active circuit according to a fourth embodiment of the present invention.
In the filter circuit 51 of the bias circuit 5, the inductors 51 e and 51 f are connected in series to the output side of the fundamental wave matching circuit 4. The capacitor 51g has one end connected between the inductors 51e and 51f and the other end connected to the ground.

In the second harmonic absorption circuit 52, the inductor 52g and the capacitor 52h are connected to the node A and constitute a parallel resonance circuit that resonates in parallel with the fundamental frequency.
The inductor 52i is connected to the parallel resonance circuit, and constitutes a series resonance circuit that performs series resonance with the second harmonic frequency together with the capacitor 52h.
Resistance element 52j has one end connected to inductor 52i and the other end connected to capacitor 53a.
The bias voltage supply circuit 53 is the same as that in FIG.

Next, the operation will be described.
In the second harmonic absorption circuit 52, the impedance with respect to the fundamental wave of the second harmonic absorption circuit 52 as viewed from the node A is opened by the parallel resonance of the inductor 52g and the capacitor 52h. Further, the filter circuit 51 constitutes a low-pass filter and passes all the fundamental wave, so that the fundamental wave of the high-frequency signal is output from the output terminal 7 without loss.

  On the other hand, the impedance to the second harmonic of the second harmonic absorption circuit 52 viewed from the node A is substantially equivalent to the resistance element 52j due to the series resonance of the capacitor 52h and the inductor 52i. Further, since the filter circuit 51 reflects the second harmonic wave, the second harmonic wave is absorbed by the resistance element 52j.

  According to the fourth embodiment, the bias circuit 5 absorbs the second harmonic frequency component without reflecting it to the high frequency transistor 2 side, thereby causing parallel resonance between the second harmonic processing circuit 3 and the bias circuit 5. As a result, it is possible to obtain an active circuit that prevents the operation of the second harmonic processing circuit 3 from being hindered and prevents deterioration in operation efficiency.

  The filter circuit 51 and the second harmonic wave absorption circuit 52 can be configured using a lumped constant circuit.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Input terminal, 2 High frequency transistor, 3,11 2nd harmonic processing circuit, 4,10 Fundamental wave matching circuit, 5,9 Bias circuit, 6, 8, 51g, 52h, 53a Capacitor, 7 Output terminal, 31, 41, 42, 51a to 51d, 52a, 52d, 52f, 101, 102, 111 Distributed constant line, 51, 91 Filter circuit, 51e, 51f, 52g, 52i Inductor, 52, 92 Double wave absorption circuit, 52b, 52c Radial stub 52e, 52j Resistive element, 53, 93 Bias voltage supply circuit, 53b Bias voltage terminal.

Claims (8)

A high frequency transistor for amplifying a high frequency signal;
A harmonic processing circuit that is connected to the output side of the high-frequency transistor and controls an impedance for a harmonic frequency that is n (n is an arbitrary natural number of 2 or more) times the fundamental frequency to an optimum position;
A fundamental matching circuit that is connected to the output side of the harmonic processing circuit and controls the impedance with respect to the fundamental frequency to an optimum position;
A bias circuit connected to the output side of the fundamental matching circuit and supplying power to the high-frequency transistor;
The bias circuit includes:
An active circuit characterized in that a fundamental frequency component is completely passed and a harmonic frequency component is absorbed without being reflected to the high frequency transistor side. The bias circuit includes:
A filter circuit that is connected to the output side of the fundamental wave matching circuit, passes all fundamental frequency components, and reflects harmonic frequency components;
A harmonic absorption circuit connected between the output side of the fundamental matching circuit and the filter circuit, resonating in parallel at the fundamental frequency, and being substantially pure resistance to the harmonic frequency;
2. The active circuit according to claim 1, further comprising a bias voltage supply circuit connected to the harmonic absorption circuit and supplying a bias voltage. A bias circuit that inputs a high-frequency signal and supplies power;
A fundamental matching circuit that is connected to the output side of the bias circuit and controls the impedance to the fundamental frequency to an optimum position;
A harmonic processing circuit that is connected to the output side of the fundamental wave matching circuit and controls an impedance for a harmonic frequency that is n (n is an arbitrary natural number of 2 or more) times the fundamental frequency to an optimal position;
A high-frequency transistor that is connected to the output side of the harmonic processing circuit and amplifies a high-frequency signal by a power source supplied from the bias circuit via the fundamental wave matching circuit and the harmonic processing circuit;
The bias circuit includes:
An active circuit characterized in that a fundamental frequency component is completely passed and a harmonic frequency component is absorbed without being reflected to the high frequency transistor side. The bias circuit includes:
A filter circuit that inputs a high-frequency signal, passes all fundamental frequency components, and reflects harmonic frequency components;
A harmonic absorption circuit connected between the filter circuit and the input side of the fundamental matching circuit, resonating in parallel at the fundamental frequency, and being substantially pure resistance to the harmonic frequency;
4. The active circuit according to claim 3, further comprising a bias voltage supply circuit connected to the harmonic absorption circuit and supplying a bias voltage. The filter circuit is
A first distributed constant line having a length ¼ times the harmonic wavelength;
A second distributed constant line having a length that is ¼ times the harmonic wavelength connected at one end to the first distributed constant line;
A third distributed constant line having a length of ¼ times the harmonic wavelength with one end connected between the first distributed constant line and the second distributed constant line and the other end open; ,
And a fourth distributed constant line having one end connected to the other end of the second distributed constant line and having a length that is ¼ times the harmonic wavelength with the other end open. The active circuit according to claim 2 or 4. The filter circuit is
A second inductor having one end connected to the first inductor;
5. The first capacitor having one end connected between the first inductor and the second inductor and the other end connected to the ground. Active circuit. The harmonic absorption circuit is
A fifth distributed constant line having a length of ¼ times the fundamental wave wavelength, one end of which is connected between the fundamental wave matching circuit and the filter circuit;
A first radial stub having one end connected to the other end of the fifth distributed constant line and having a length that is 1/4 times the fundamental wavelength with the other end open;
A second radial stub having one end connected to the other end of the fifth distributed constant line and exhibiting capacitance with respect to a harmonic frequency having the other end open;
A sixth distributed constant line having a length of ¼ times the harmonic wavelength, one end connected to the other end of the fifth distributed constant line and the other end connected to the bias voltage supply circuit;
A resistance element having one end connected to the other end of the fifth distributed constant line;
7. A seventh distributed constant line having one end connected to the other end of the resistance element and having a length that is 1/4 times the harmonic wavelength, the other end being open. The active circuit according to claim 4. The harmonic absorption circuit is
A third inductor having one end connected between the fundamental matching circuit and the filter circuit;
One end connected between the fundamental matching circuit and the filter circuit, and a second capacitor constituting a parallel resonance circuit that resonates in parallel with the third inductor with respect to a fundamental frequency,
A fourth inductor that constitutes a series resonance circuit having one end connected to the other ends of the third inductor and the second capacitor, and in series resonance with the second capacitor with respect to a harmonic frequency;
5. The active circuit according to claim 2, further comprising: a resistance element having one end connected to the other end of the fourth inductor and the other end connected to the bias voltage supply circuit.

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