KR100696212B1 - A method for avoiding high-frequency oscillation in high impedance amplification circuit - Google Patents

Abstract

A high-frequency oscillation prevention method in a high-impedance amplifying circuit and a ground implement are provided to minimize the influence of distributed capacity between components or collector capacity by installing the ground implement to approach a ground electrode having stable potential to a transistor element when the transistor element is disposed in a circuit board. In a constant current darlington transistor circuit in which the first transistor(Qa1) and the second transistor(Qa2) are approached and disposed, a band unit and a ground lead unit are combined. The band unit is formed as an electric closed-circuit to approach and cover the circumference of the first transistor(Qa1) and the second transistor(Qa2). The ground lead unit is electrically connected to the band unit and is electrically connected to a pattern of a circuit board.

Description

A METHOD FOR AVOIDING HIGH-FREQUENCY OSCILLATION IN HIGH IMPEDANCE AMPLIFICATION CIRCUIT}

Figure 1a: embodiment in which the improved ground mechanism is installed in the present invention

Figure 1b: Example of an amplifier circuit experimented in the present invention

1C: perspective view of the grounding mechanism of the first embodiment

1D: perspective view of the grounding mechanism of the second embodiment

1E: perspective view of the folding mechanism of the third embodiment

2A: An explanatory diagram showing a distribution capacity relationship with peripheral components in the prior art

2b is an exploded view showing the capacitance relationship between electrodes in a transistor;

Figure 2c: Example amplifier circuit diagram experimented in the prior art

2d: Circuit and Operational Concept of Constant Current Darlington Transistor

In an amplifier using a constant current Darlington transistor with high input impedance characteristics, the present invention relates to an improvement method for removing noise due to high frequency oscillation or interference by capacitance between electrodes of transistor elements and distribution capacitance between circuit elements in a batch. .

FIG. 2C is a circuit diagram of a two-class Class-A voltage amplifier using a constant current Darlington transistor, which was used as an amplification circuit for experimenting the influence on the inflow of external signals in the high input impedance circuit.

A base terminal (b) connected to the base of the first transistor Q2a1, an emitter of the first transistor Q2a1, a resistor R2a1 and a base of the second transistor Q2a2, and a emitter of the second transistor Q2a2 and a constant voltage source CV2a1, The first constant current Darlington transistor comprising a collector terminal (c) to which the collector of the first transistor Q2a1 and the collector of the second transistor Q2a2 are connected, and an emitter terminal (e) to which the other terminal of the resistor R2a1 and the other terminal of the constant voltage source CV2a1 are connected. CCD21;

A base terminal (b) connected to the base of the third transistor Q2b1, an emitter of the third transistor Q2b1, a resistor R2b1, a base of the fourth transistor Q2b2, and a emitter of the fourth transistor Q2a2 and a constant voltage source CV2a1, A second constant current darlington transistor comprising a collector terminal (c) to which the collector of the third transistor Q2b1 and the collector of the fourth transistor Q2b2 are connected, and an emitter terminal (e) to which the other terminal of the resistor R2b1 and the other terminal of the constant voltage source CV2b1 are connected. CCD22;

An input terminal configured to connect an input terminal IN2 receiving the input signal and a base of the CCD21 and a first capacitor C21 for direct insulation;

A bias stage comprising resistors R22 and R23 for dividing the power supply voltage for biasing the base of the CCD21 and resistor R24 for supplying the divided bias voltage to the base of the CCD21;

The first load resistors R25 and emitters of the CCD21 connected to the base (b) of the CCD21 receiving the input signal and the collector (c) of the CCD21 outputting the amplified current are converted into voltage and output the signal to the next stage. a first voltage amplifier stage composed of a first emitter resistor R26 connected to e);

The second load resistors R28 and Emmy of the CCD22 are connected to the base (b) of the CCD22 receiving the output signal of the previous stage and the collector (c) of the CCD22 which outputs the amplified current, and are converted into voltage and output the signal to the next stage. A second voltage amplifier stage consisting of a second emitter resistor R29 connected to the emitter e;

An output terminal including an output terminal OUT2 for outputting the output signal amplified by the second voltage amplifier stage and a second capacitor C22 for directly separating the collectors of the output terminals OUT2 and CCD22; It consists of.

2C is a voltage amplifier constructed in two stages using a constant current Darlington transistor as an amplifying element.

Referring to FIG. 2D, the operation of the constant current Darlington transistor

When the input signal of IN1 rises, ibe1 increases, and ice1 of Q1 also increases. Most of ice1 passes through R1, and the voltage at point A increases because the voltage across R1 rises by iR1. In addition, the increase in point A increases the ibe2 of Q2, which increases the Q2 collector current ice2 and lowers the impedance between the collector and emitter of Q2. Since the voltage at both ends of the constant voltage source in the emitter of Q2 is constant, the potential of point B increases by the load LD1, and the point C also increases. As point C rises, the voltage across R1 decreases again, iR1 current decreases, and ice1 also decreases so that ice1 remains in its previous state (constant current operation of R1). At this time, ibe1 also decreases to maintain the previous state. Q2 controls ice1 to always be constant. There is only a change in the voltage at point B because the input signal has risen.

2D shows Q1 and Q2 as the conventional Darlington circuit. We put a constant voltage source in the emitter of Q2 and a resistor in the emitter of Q1. Here, Q2 is controlled so that the current flowing in R1 is always constant by the constant voltage source consisting of the voltage Vbe_Q2 between the base and emitter of Q2 and the constant voltage source CV1. Therefore, the collector-emitter current of Q1 is always constant, so the base current of Q1 is also constant. That is, the constant base current of Q1 is the same as no current flows alternatingly. In other words, since the signal current by the input signal voltage does not flow to the base of Q1, the input impedance is high, and thus it acts as a voltage amplifier.

The constant current Darlington transistor used as an amplifying device in Fig. 2c is a voltage amplifying device having a high input impedance. Since the input impedance of the constant current Darlington transistor is high, it is possible to design a high impedance of the bias circuit of the base. By designing high impedance of bias circuit

Since the input signal voltage flows directly into the base without current flow, the waveform of the input signal is not deformed and flows into the base of the constant current Darlington transistor to be amplified and output as a current signal to the collector. That is, it is a high fidelity voltage amplifier that amplifies the input signal voltage without distortion.

In FIG. 2C, the input signal is first amplified in the first voltage amplifier stage composed of the CCD21, R25, and R26, and secondly amplified in the second voltage amplifier stage composed of the CCD22, R28, and R29. The DC voltage of the collector (c) of the CCD22 of the second voltage amplifier stage becomes 1/2 of the power supply voltage, which is a normal DC bias state.

The amplification operation of FIG. 2C will be described from an AC perspective.

The amplification operation in the first voltage amplifier stage

If the input signal rises by v, the impedance of the bias stage is designed to be high and the input impedance of the CCD 21 is high, so that the input signal is not attenuated, thereby increasing the base voltage of the CCD 21 by v. Q2a2 of the CCD21 is controlled so that the voltage between the base (b) and the emitter (e) of the constant current Darlington transistor is always constant, so that the emitter voltage of the CCD21 also increases by v as the input voltage increases. At this time, the signal current i_R26 flowing in the first emitter resistor R26 is

i_R26 = v / R26 (Equation 1)

And the current of i_R26 will flow equally to the collector of CCD21. At this time, the signal voltage v_R25 generated in the collector of CCD21 is

v_R25 = i_R26 * R25

Substituting Equation 1

v_R25 = (v / R26) * R25

v_R25 = v * R25 / R26 (Equation 2)

Here, the voltage amplitude A1 of the first voltage amplifier stage is

A1 = v_R25 / v

A1 = v * R25 / R26 / v

A1 = R25 / R26 (Equation 3)

The input signal voltage is amplified by A1 times and is generated across the resistor R25 connected to the collector. In this case, the amplified output signal is a voltage in which the phase of the input signal v is inverted by 180 degrees.

The amplification operation in the second voltage amplifier stage

If the output signal amplified by the first voltage amplification stage v_R25 is increased, the input impedance of the CCD22 is high so that the input signal is not attenuated, thereby increasing the base voltage of the CCD22 by v_R25. Since Q2b2 of the CCD22 is controlled so that the voltage between the base (b) and the emitter (e) of the constant current Darlington transistor is always constant, the emitter voltage of the CCD22 is also increased by v_R25 as the input voltage is increased. At this time, the signal current i_R29 flowing in the second emitter resistor R29 is

i_R29 = v_R25 / R29 (Equation 4)

And the current of i_R29 will flow equally to the collector of CCD22. At this time, the signal voltage v_R28 generated in the collector of CCD22 is

v_R28 = i_R29 * R28

Substituting Equation 4

v_R28 = (v_R25 / R29) * R28

v_R28 = v_R25 * R28 / R29 (Equation 5)

Here, the voltage amplification degree A2 of the second voltage amplifier stage is

A2 = v_R28 / v_R25

A2 = v_R25 * R28 / R29 / v_R25

A2 = R28 / R29 (Equation 6)

The input signal voltage is amplified by A2 and generated across the resistor R28 connected to the collector. In this case, the amplified output signal is a voltage in which the phase of the output signal v_R25 of the first voltage amplifier stage is inverted by 180 degrees.

Alternatively, the voltage is output in the same phase as the input signal v of the input terminal IN2.

Here, in the amplifier of FIG. 2C, the first voltage amplifier stage and the second voltage amplifier stage are connected in series, so that the overall amplification degree is equal to the amplification degree of the first voltage amplifier stage and the second voltage amplifier stage. Amplitude A_TOT

A_TOT = A1 * A2

A_TOT = (R25 / R26) * (R28 / R29)

A_TOT = R25 * R28 / R26 * R29 (Equation 7)

In the voltage amplifier of FIG. 2C, an A_TOT times amplified signal is output.

Here, we will explain the cause of external signal influencing amplified signal from voltage amplifier composed of high input impedance circuit.

Explain the first cause

When a part of the output signal of the second voltage amplifier stage flows into the input circuit element of the first voltage amplifier stage when the circuit component of FIG. It operates in an unstable state and the output signal is not stable.

In this way, a part of the output signal is fed back to the input circuit element is fed back by the distribution capacity between components because the two circuit intervals are narrow or the volume of the circuit element is large. Also, the higher the input impedance of the input circuit, the easier it is to be fed back. Due to the high input impedance of the constant current Darlington transistor, this feedback oscillation or operation may become unstable. In addition, the higher the signal frequency, the larger the signal inflow due to the distribution capacity, and the inflow of the high frequency increases.

2A shows some components of the arrangement of the circuit of FIG. 2C on the actual substrate.

In Fig. 2A, the transistors Q2a1 and Q2a2 used in the CCD21 of the first voltage amplifier stage are arranged in close proximity, and the transistors Q2b1 and Q2b2 used in the CCD22 of the second voltage amplifier stage are placed in proximity and are not displayed in the circuit of Fig. 2C. Although not yet, the capacitor C2c1, which is a component of the third voltage amplifier stage, is disposed.

The base circuit of transistor Q2a1 of the first voltage amplifier stage has a high impedance and a high input sensitivity. The path through which external signals flow into this Q2a1 element is due to the distribution capacity between the surrounding components. It is fed back to Q2a1 or mixed with noise by the distribution capacitance C_d21 of the second voltage amplifier stage and the distribution capacitance C_d22 of the third voltage amplifier stage.

When the amplified signal is fed back from the same amplifier, oscillation or operation becomes unstable, and the signal fed back from the other amplifying circuit acts as noise, thereby amplifying the output signal into an unclean signal.

The effect of the distribution capacity is very small at low frequencies, but the higher the frequency, the greater the effect. The higher the frequency, the more the oscillation occurs at frequencies where the phase difference is 0 degrees.

Explain the second cause

2B is an exploded view of an inside of a general small output transistor.

There is a lead frame composed of transistor base, collector, and emitter lead and collector plate and acting as a heat sink.The bare chip, which is the main body of the transistor, is bonded to the plate connected to the collector. The emitter terminal is connected to each lead frame by a wire bonding method.

There is also a capacitance between each terminal of the leadframe, the base, collector and emitter. There is a distributed capacitance C_ce between the emitter and the collector and C_cb, the capacitance between the base and the collector.

In addition, in order to fabricate a transistor on a silicon wafer, each electrode is formed, but the distribution capacitance exists in the interface between the base electrode and the collector. This distribution capacitance is the collector capacitance Cob that is also displayed in the transistor data sheet. This Cob is characterized by a change depending on the voltage between the base and the collector, and is characterized by different transistor types.

When the capacitance C_cb between the base lead and the collector lead and the collector capacity Cob are summed, it is called the collector capacity.

The signal input to the base is amplified to output a 180 degree inverted signal from the collector, and the output signal is fed back back to the base (a kind of negative feedback) by the collector capacity between the base and the collector to reduce the input signal to some extent. do. This effect is very small at low frequencies, but the higher the frequency, the greater the influence. As the frequency increases, the phase difference becomes smaller than 180 degrees and oscillates at a frequency where the phase difference is 0 degrees.

As a method of generating oscillation at high frequency or minimizing unstable operation due to inflow of external signal due to distribution capacitance according to arrangement on the circuit board and collector capacity of transistor element in high impedance circuit elements such as constant current Darlington transistors. When disposing the transistor on a circuit board, a grounding mechanism having a stable electric potential is provided in close proximity to the transistor element to minimize the influence of the distribution capacitance (C_d21, C_d22) or collector capacitance (Cob, C_cb) between components. And we propose a variety of grounding mechanisms.

FIG. 1B is a circuit diagram of a two-class Class-A voltage amplifier using a constant current Darlington transistor, which is used as an amplification circuit for experimenting the influence on the inflow of an external signal in a high input impedance circuit.

Amplification circuit configuration of Figure 1b

A base terminal (b) connected to the base of the first transistor Qa1, an emitter of the first transistor Qa1, a resistor Ra1 and a base of the second transistor Qa2, and a emitter of the second transistor Qa2 and a constant voltage source CVa1, The first constant current darlington transistor comprising a collector terminal (c) to which the collector of one transistor Qa1 and the collector of the second transistor Qa2 are connected, and an emitter terminal (e) to which the other terminal of the resistor Ra1 and the other terminal of the constant voltage source CVa1 are connected. CCD1;

A base terminal (b) connected to the base of the third transistor Qb1, an emitter of the third transistor Qb1, a resistor Rb1, a base of the fourth transistor Qb2, and a emitter of the fourth transistor Qa2 and a constant voltage source CVa1, A second constant current darlington transistor comprising a collector terminal (c) to which the collector of the third transistor Qb1 and the collector of the fourth transistor Qb2 are connected, and an emitter terminal (e) to which the other terminal of the resistor Rb1 and the other terminal of the constant voltage source CVb1 are connected. CCD2;

An input terminal configured to connect an input terminal IN for receiving an input signal, a base of the CCD1, and a first capacitor C1 for direct insulation;

A bias stage consisting of resistors R2 and R3 for dividing the power supply voltage for bias on the base of CCD1 and resistor R4 for supplying the divided bias voltage to the base of CCD1;

The first load resistor R5 and the emitter of the CCD1 are connected to the base (b) of the CCD1 receiving the input signal and the collector (c) of the CCD1 for outputting the amplified current, and are converted into voltage and output the signal to the next stage. a first voltage amplifier stage consisting of a first emitter resistor R6 connected to e);

The second load resistors R8 and Emmy of the CCD2 are connected to the base (b) of the CCD2 receiving the output signal of the preceding stage and the collector (c) of the CCD2 outputting the amplified current, and are converted into voltage and output the signal to the next stage. A second voltage amplifier stage consisting of a second emitter resistor R9 connected to the emitter e;

An output terminal including an output terminal OUT for outputting the output signal amplified by the second voltage amplifier stage and a second capacitor C2 for directly separating the collectors of the output terminal OUT and the CCD2; It consists of.

1A shows some components of the arrangement of the circuit of FIG. 1B on an actual substrate.

In FIG. 1A, a first transistor group in which transistors Qa1 and Qa2 used in CCD1 of the first voltage amplifier stage are adjacent to each other and a second transistor group in which transistors Qb1 and Qb2 used in CCD2 of the second voltage amplifier stage are adjacent to each other are illustrated. Although not shown in the circuit of 1b, an amplifier in which a capacitor Cc1, which is another component of the third voltage amplifier stage, is assembled on a circuit board

It is installed close to the periphery of the transistors Qa1 and Qa2 of the first transistor group and is installed close to the periphery of the transistors Qb1 and Qb2 of the first grounding mechanism PG1 and the second transistor group connected to the ground pattern GND1 and connected to the ground pattern GND1. The second grounding mechanism PG2 is installed.

The first embodiment of the grounding mechanism

In FIG. 1C

It is composed of an electrical conductor and a band part which is closed circuit to wrap around the transistor of the transistor group, and is electrically connected to the band part and functions to fix the band part, and is composed of a ground lead part for connecting to the ground pattern GND1 of the circuit board. have.

The second embodiment of the grounding mechanism

In FIG. 1D

It is made of an electrical conductor and closed circuit to wrap around the transistors in the transistor group. However, one side of the band is cut off and the band part has a clip connection part formed at the end of the band. It consists of a ground lead part for connecting to the ground pattern of the circuit board.

The third embodiment of the grounding mechanism

In FIG. 1E

It is made of an electrical conductor and closed circuit to wrap around the transistors in the transistor group, and the band part is electrically connected to the band part and the band part where the guide is installed so that the band position is in a certain position of the transistor. It is composed of a ground lead for connecting to the ground pattern of the circuit board.

When explaining the practice of the present invention

Figure 1b is a voltage amplifier composed of a two-stage series using a constant current Darlington transistor as an amplification device, and used as an amplifying circuit to test the effect on the inflow of an external signal in a high input impedance circuit, such as a constant current Darlington transistor.

1A shows some components of the arrangement of the circuit of FIG. 1B on an actual substrate.

In the voltage amplifier composed of a high input impedance circuit, as shown in FIG. 1A, an improved operation for the influence of the amplified signal by installing a grounding mechanism as shown in FIG. 1A is described above. Divided into two reasons explained in

The explanation for the improved first cause

When the circuit component of FIG. 1B is disposed and operated on the circuit board as shown in FIG. 1A, a part of the output signal of the second voltage amplifier stage flows into the input circuit element of the first voltage amplifier stage by the distribution capacitor C_d11. At this time, the first grounding mechanism PG1 surrounding the first transistor groups Qa1 and Qa2 of the first voltage amplifier stage is connected to the ground pattern GND1 of the electrically stable circuit board, so that the first grounding mechanism PG1 and the transistor Qa1 are connected. The distribution capacitance C_g11 is present, and this C_g11 becomes larger than the distribution capacitance C_d11 with the second voltage amplifier stage. Therefore, the feedback signal due to the voltage generated in the second voltage amplifier stage is divided into C_d11 and C_g11 and flows into Qa1.

Here, the voltage generated at the second voltage amplifier stage is called v_ss, and the signal v_d1 flowing into Qa1 is

Capacitor capacity and impedance are inversely proportional.

v_d1 = v_ss * C_d11 / (C_d11 + C_g11) (Equation 10)

If the distribution capacity C_g11 between the first grounding mechanism PG1 is sufficiently larger than the distribution capacity C_d11 with the second voltage amplifier stage,

 v_d1 = v_ss * C_d11 / C_g11 (Equation 11)

Then, the signal v_d1 flowing into Qa1 is divided by each distribution capacitance and is reduced to C_d11 / C_g11. That is, the signal fed back becomes small, making it difficult to oscillate, and the amplification operation is stabilized. In addition, even if the signal frequency is increased, the attenuation ratio does not change. Rather, the impedance of the two distribution capacitors is lowered, so that it is difficult to diverge to the ground and bypass.

Although not shown in the circuit of FIG. 1A to FIG. 1B, the operation of the distribution capacitor C_d12 by the capacitor Cc1 which is another component of the third voltage amplifier stage also works in the same manner, thereby reducing the noise flowing from the other amplifier circuits, thereby making the amplification signal clean. .

The explanation for the improved second cause

As shown in FIG. 2B, the capacitance C_ce between the emitter and the collector and the capacitance C_cb between the base and the collector are among the capacitances between the base, the collector, and the emitter lead inside the small output transistor, or the transistor on the silicon wafer. There is a collector capacitance Cob that exists at the interface between the electrode of the base and the collector to form each electrode in order to fabricate.

The operation by this collector capacity Cob

Since the first grounding mechanism PG1 surrounding the first transistor groups Qa1 and Qa2 is connected to the ground pattern GND1 of the electrically stable circuit board, the distribution capacity C_g11 is established between the first grounding mechanism PG1 and the transistor Qa1. It exists.

The distribution capacitor C_g11 is connected in series between the collector and the base between the collector capacitor Cob and the base and the first grounding mechanism PG1.

Therefore, the feedback signal generated by the voltage generated at the collector will generate a voltage divided by Cob and C_g11 at the base.

Here, the voltage generated at the collector is called v_cc, and the signal v_d2 generated at the base of Qa1 is

Capacitor capacity and impedance are inversely proportional.

v_d2 = v_cc * Cob / (Cob + C_g11) (Equation 20)

If the distribution capacity C_g11 between the first grounding mechanism PG1 and the base is sufficiently larger than the collector capacity Cob,

 v_d2 = v_cc * Cob / C_g11 (Equation 21)

Then, the signal v_d2 generated at the base of Qa1 is divided by each distribution capacitance and is reduced to Cob / C_g11. In other words, the effect of negative feedback of the inverted and amplified collector signal to the base is reduced, and the amplification operation is stabilized. In addition, even if the signal frequency is increased, the attenuation ratio does not change. Rather, the impedance of the two capacitors Cob and C_g11 is lowered, thereby bypassing the ground, and the high frequency signal is attenuated.

The grounding mechanism PG1 or PG2 is effective to absorb external noise or unnecessary signal components.

In other words, the grounding electrode is installed to approach the transistor by the grounding mechanism. The grounding mechanism has the effect of shielding the transistor, reducing the unnecessary high frequency, blocking the very high frequency, and affecting the low frequency. It is characterized by the absence of.

In addition, rather than using a capacitor made of parts for the purpose of attenuating the high frequency signal induced in the high input impedance circuit by connecting the ground pattern, the grounding mechanism of the present invention uses an insulating layer between the ground mechanism and the transistor as air. Because of this, the electrical characteristics are very good due to the effect of the air capacitor which has excellent insulation and excellent frequency characteristics.

When explaining the grounding mechanism of the first embodiment

In FIG. 1C

A ground lead is connected to electrically ground the band part, which is made of an electrical conductor and is wrapped around the transistor of the transistor group, and the grounding mechanism itself is grounded by soldering the ground lead to the ground pattern of the circuit board. It becomes an electric potential of the level, it becomes an electrical stable state, it fixes an band part, and it is effective in absorbing external noise and unnecessary signal components.

That is, the grounding electrode is installed close to the transistor by the grounding mechanism. The grounding mechanism has the effect of shielding the transistor, reducing the unnecessary high frequency, blocking the very high frequency, and affecting the low frequency. It is characterized by the absence of.

When explaining the grounding mechanism of the second embodiment

In FIG. 1D

It is made of electrical conductor and has a band shape to wrap around the transistor in the transistor group, and one side of the band is cut off, and a clip fastening part is formed near the end of the band, so the clip is installed in a loose state and the clip is locked after installation. It is easy to install. A ground lead is formed to electrically ground the band, and by grounding the ground lead to the ground pattern of the circuit board, the grounding mechanism itself becomes a potential of the circuit grounding level, thereby becoming electrically stable and fixing the band. It is effective in absorbing noise and unnecessary signal components.

That is, the grounding electrode is installed close to the transistor by the grounding mechanism. The grounding mechanism has the effect of shielding the transistor, reducing the unnecessary high frequency, blocking the very high frequency, and affecting the low frequency. It is characterized by the absence of.

When explaining the grounding mechanism of the third embodiment

In FIG. 1E

It is an electrical conductor and has a flat band so as to surround the transistors of the transistor group, and a guide is provided so that the bands are located at the constant positions of the transistors. A ground lead is formed to electrically ground the band, and by grounding the ground lead to the ground pattern of the circuit board, the grounding mechanism itself becomes a potential of the circuit ground level, thereby becoming electrically stable and fixing the band. It is effective in absorbing unnecessary signal components.

That is, the grounding electrode is installed close to the transistor by the grounding mechanism. The grounding mechanism has the effect of shielding the transistor, reducing the unnecessary high frequency, blocking the very high frequency, and affecting the low frequency. It is characterized by the absence of.

The grounding mechanism of the third embodiment is characterized in that the guide and the grounding lead can be manufactured from a flat metal plate by a press die, so that the manufacturing cost can be reduced by automation.

1. By using grounding mechanism, oscillation or noise caused by high frequency can be minimized, and stable amplification operation can be achieved and the input signal can be amplified faithfully.

2. It has a shielding effect against high frequency by installing grounding mechanism.

3. The electrical characteristics are very good due to the effect of air capacitor between the grounding device and the transistor.

4. By fixing the transistors of a plurality of transistor groups with a grounding mechanism, there is an effect of preventing vibration and alignment.

Claims (4)

In the constant current Darlington transistor circuit in which the first transistor Qa1 and the second transistor Qa2 are disposed in close proximity to each other. The ground part is coupled to the band part which is an electrically closed circuit and the band part which is electrically closed so as to surround the circumferences of the first transistor Qa1 and the second transistor Qa2 in close proximity and is electrically connected to the pattern of the circuit board. Device. A grounding mechanism consisting of an electrical conductor and a band portion, which is a closed circuit so as to surround a transistor of a transistor group, and a grounding lead portion which is electrically connected to the band portion and connected to a pattern of a circuit board. It is an electrical conductor and has a closed circuit to cover the circumference of the transistors in the transistor group, but one of the bands is broken and the ground lead for connecting to the circuit board pattern while being electrically connected to the band part where the clip connection part is formed and the band part. Grounding mechanism consisting of parts. It is made of an electrical conductor and closed circuit to surround the transistors of the transistor group. The band is connected to the circuit board pattern while the band is electrically connected to the band part and the band part where the guide is installed so as to be in a certain position of the transistor. Grounding mechanism consisting of a grounding lead for

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