JPS64846B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is directed to an amplification device, in particular an analog signal integrated circuit (linear IC), which enables high-fidelity, high-output signals to be easily obtained. It is intended to easily provide an amplifying device suitable for an amplifying device, for example, an amplifying device for audio equipment.

(Conventional Examples and Problems) Audio equipment often requires amplifiers that can obtain high-output signals with high fidelity, and various types of amplifiers have been provided. As is well known.

FIG. 1 is a block diagram showing the basic configuration of an amplifier currently most commonly used as an amplifier constructed using individual parts.
In this Figure 1, 1 is an input terminal, Q1 to Q9
is a transistor, CC is a constant current source circuit, 1 to 4 are resistors, E1 to E3, +Vcc, -Vcc are power supplies, Ao is an amplifier (usually a power amplifier with a gain of 1 is used as the amplifier Ao), 5 is the output terminal,
The amplifier device shown in the first diagram includes a differential amplifier circuit composed of transistors Q1 and Q2, a constant current source circuit CC, resistors 2 and 3, and transistors Q7 to Q9.
current mirror circuit, resistor 4 and transistor Q
3 to Q6, and an amplifier A having a gain of 1.

In the amplifier device shown in FIG.
The circuits of No. 3 and Q4, the circuit of transistors Q5 and Q6, and the circuit of transistors Q8 and Q9 are each configured as a cascode amplifier circuit to prevent deterioration of signal linearity at the time of large amplitude.

The conventional amplifying device shown in FIG. 1 has a large number of parts, takes time to manufacture, and is expensive. In addition, the voltage generated in the resistor 4, the voltage of the power supplies E1 to E3, etc. Since the presence of the amplifier lowers the effective utilization rate of the power supply voltage, there are problems such as disadvantages when trying to obtain a large output from the amplifier, and there has been a desire to improve this problem.

Further, FIG. 2 is a block diagram of another example of the configuration of the conventional amplifier device, and in this FIG. 2, 1 is an input terminal, Ai, Ao are amplifiers,
An input signal applied to input terminal 1 is amplified by amplifier Ai, and then supplied via resistor R1 to the emitter of transistor Q10 constituting a common base type amplifier circuit.

As is well known, the input impedance of a common base type amplifier circuit is extremely low, so the amplifier Ai
Let the voltage Vo of the output signal be the transistor Q
The magnitude of the signal current i supplied to the emitter of transistor Q10 via the resistor R1 is expressed as i=Vo/R1, and the output signal from the collector of the transistor Q10 constituting the common base amplifier circuit. The current also becomes i.

The output signal current i of the transistor Q10 constituting the common base amplifier circuit is transmitted through the transistors Q11 to Q11 constituting the current mirror circuit.
It is applied to the input side circuit of amplifier Ao via Q13.

By the way, since the constant current source circuit CC1 is provided in the input side circuit of the amplifier Ao, the input side circuit of the amplifier Ao
On the input side of the circuit, a signal is generated which shows a large voltage change corresponding to the output signal i appearing through the current mirror circuit described above. In addition, in Figure 2, R
2, R3 are correction resistors, E4, E5 are power supplies, and transistor Q1 in the current mirror circuit.
2 and Q13 constitute a cascode amplifier circuit.

In the amplifying device shown in the second diagram, the signal current i supplied via the resistor R1 to the emitter of the transistor Q10 constituting the common base amplifying circuit by the output signal of the amplifier Ai is transmitted via the current mirror circuit. This is applied to a high impedance circuit, where it is converted into a large voltage change. Therefore, for example, even if a linear IC that cannot generate a large output signal voltage is used as amplifier Ai, a large signal voltage cannot be applied to the input side of amplifier Ao. Therefore, the amplifying device having the configuration shown in the second diagram has the advantage that a high output amplifying device can be easily provided with a circuit configuration having a small number of parts, and is economically excellent. It can be called a circuit.

However, in the amplifier shown in FIG. 2, deterioration of linearity occurs due to changes in mutual conductance of transistors Q11 and Q12 used in the configuration of the current mirror circuit, and deterioration of linearity occurs in correction resistors R2 and R3. The signal voltage may cause deterioration of high frequency characteristics through parasitic capacitance, etc.
Due to the presence of transistor Q13 and power supply E5,
There were problems such as a worsening of the power utilization rate on the negative side, and improvements were desired.

(Means for Solving the Problems) The present invention provides a base or a gate (first electrode)
, an emitter or source (second electrode), and a collector or drain (third electrode).
It comprises at least three electrodes: an electrode, a base or gate (first electrode), an emitter or source (second electrode), and a collector or drain (third electrode), and the first active element described above. A constant current circuit or a resistor is connected between the connection point connecting the second electrode of the second active element having a different conductivity type and the reference potential point, and the second electrode is connected to the reference potential through the impedance. The output signal of the preceding stage amplifier is supplied to the first electrode of the first active element, which is connected to a point to constitute a second electrode grounded type amplifier circuit; The circuit of the second active element constitutes a first electrode grounding type amplifier circuit, and furthermore, the output signal is obtained from the circuit on the third electrode side of the second active element. The present invention provides an amplification device.

(Example) Hereinafter, specific contents of the amplifier device of the present invention will be explained in detail with reference to the accompanying drawings. FIG. 3 is a block diagram for explaining the configuration principle and operating principle of the amplifying device of the present invention, FIG. 4 is a block circuit diagram of an embodiment of the amplifying device of the present invention, and FIG. The explanatory curve diagrams, FIGS. 6 and 7, are block circuit diagrams of other embodiments of the amplifier device of the present invention.

In FIG. 3, Ai is an amplifier, and the input signal supplied to the input terminal 1 is amplified by the amplifier Ai and then applied to the first electrode of the first semiconductor active element Qa.

In the illustrated example, transistors having different conductivity types are used as the first semiconductor active element Qa and the second semiconductor active element Qb, which will be described later. Among them, each electrode in each transistor Qa and Qb used as the first and second semiconductor active elements is referred to as the base as the first electrode, the emitter as the second electrode, and the collector as the third electrode. There is also. Note that the first and second semiconductor active elements Qa, Qb
In the case where the amplifier device of the present invention is configured using field effect transistors (FETs) having different conductivity types, the first and second semiconductor active elements Qa and Qb, It goes without saying that the first electrode corresponds to the gate, the second electrode corresponds to the source, and the third electrode corresponds to the drain.

Now, the emitter of the transistor Qa is grounded through the impedance Z1, the circuit of the transistor Qa constitutes a common emitter type amplifier circuit, and the collector of the transistor Qa is
It is connected to the emitter of the transistor Qb used as the second semiconductor active element Qb, and is also connected to a reference potential point (ground point in the illustrated example) via a constant current circuit or impedance Z2. Further, since the base of the transistor Qb described above is grounded, the circuit of the transistor Qb constitutes a common base type amplifier circuit.

In the amplifier shown in FIG. 3, the transistor Qa
In the circuit, the emitter is grounded via an impedance Z1 that acts as a current feedback resistor,
Since the emitter-grounded amplifier circuit is configured, the voltage between the base and emitter of the transistor Qa is approximately constant. Therefore, when the output voltage Vo from the amplifier Ai is supplied to the base of the transistor Qa, A current i of i=Vo/Z1 flows through the impedance Z1 connected to the emitter of Qa, but since the current amplification factor α of the transistor Qa is close to 1, the above current i flows through the impedance Z1 connected to the emitter of Qa.
It is output from the collector side of Qa, and the transistor
A current having a current value i is supplied to the emitter of Qb.

Since the circuit of the transistor Qb whose emitter is supplied with a current value i as described above constitutes a common base type amplifier circuit, the current flowing through the circuit on the collector side of the transistor Qb also has a current value i. It becomes.

In this way, in the circuit arrangement shown in FIG. 3, even if the current mirror circuit used in the conventional example circuit shown in FIG. Therefore, when a constant current circuit is connected to the collector circuit of transistor Qb, as the current i changes, a current can be generated in the collector circuit of transistor Qb. It is clear that large voltage changes can occur. In addition, in FIG. 3, the collector of the first transistor Qa and the second transistor
The resistor Z2 connected between the connection point with the emitter of Qb and the reference potential point (ground point in the illustrated example) is
This is so that the current flowing therein can be used as a base bias to operate the transistor Qb at a predetermined operating point.

As is clear from a comparison between the amplifying device of the present invention shown in the third figure and the conventional devices shown in the first and second figures,
The amplifying device of the present invention has a simpler configuration than the conventional device shown in the first drawing, and also has a simpler structure than the conventional device shown in the second drawing.
It is possible to easily configure a high-output amplification device by using an IC for the amplifier Ai, and the amplification device of the present invention does not use a current mirror circuit, and the amplification device of the present invention does not use a cascade connection. being done 2
Even if the mutual conductance values of the two transistors Qa and Qb change with a change in the magnitude of the current flowing through the transistors, the manner of the change is opposite to that of the transistors Qa and Qb and is canceled out. Therefore, the various problems that occurred in the conventional device due to the use of a current mirror circuit do not occur in the amplifier device of the present invention. The problem of a decrease in the utilization rate of the power supply voltage, which has been a problem, does not occur.

Next, a specific circuit example of the amplifier device of the present invention will be described with reference to the drawings shown in FIG. 4 and subsequent figures. First, in the circuit of an embodiment of the amplifier device of the present invention shown in FIG. 4, 1 is an input terminal, 5 is an output terminal, and Ai and Ao are amplifiers, where the amplifier Ai is, for example, a linear IC, and Ao is, for example, a gain is the output amplifier of 1, and in Fig. 4, Qa,
Qb and Qc are transistors, Ra, Rb and 6 to 9 are resistors, 10 and 11 are diodes, 12 and 13 are Zener diodes, and +Vcc and -Vcc are positive and negative power supplies.

In the amplifier shown in FIG. 4, the circuit including the resistor 6 and the Zener diode 12, the circuit including the resistor 7 and the Zener diode 13, etc.
If Ai is configured to operate at a relatively low operating voltage, such as a linear IC, the power supply +Vcc, -, which has a voltage value higher than the operating voltage of the amplifier Ai described above, is used. This is a power supply circuit used to generate the operating voltage for amplifier Ai from Vcc.

In the amplifier shown in FIG. 4, a signal applied to input terminal 1 is amplified by amplifier Ai and applied to the base of transistor Qa. The emitter of the transistor Qa is connected to +Vcc via a resistor Ra that operates as a current feedback resistor.
Since the circuit of the transistor Qa constitutes a common emitter type amplifier circuit, the voltage between the base and emitter of the transistor Qa is approximately constant.

Now, the voltage of the output signal from the amplifier Ai applied to the base of the transistor Qa mentioned above is Vo
When , a current represented by i=Vo/Ra flows through the resistor Ra connected to the emitter of the transistor Qa, and since the current amplification factor α of the transistor Qa is approximately 1, the current amplification factor α of the transistor Qa is approximately 1. The current flowing from the collector to the emitter of transistor Qb is i.

In the amplifier shown in Figure 4, +Vcc power supply and -
Transistor installed between Vcc power supply
A circuit consisting of Qc, resistor 8, diode 10,
The circuit consisting of the transistor Qb, the resistor Rb, and the diode 11, including the resistor 9, constitutes an individual constant current circuit.

By the way, in a constant current circuit consisting of a transistor Qb, a resistor Rb, and a diode 11 (including the circuit of the diode 10 and the resistor 9), the base of the transistor Qb is connected between the +Vcc power supply and the -Vcc power supply. A constant voltage is always applied from the connection point between the resistor 9 and the diode 11 in the series connection circuit of the diode 10, the resistor 9, and the diode 11.

Therefore, the circuit of transistor Qb essentially operates as a base-grounded amplifier circuit, and its input impedance is extremely small. Therefore, the current i supplied to the emitter of transistor Qb is It is output to the collector side of the transistor Qb without being affected much by the resistor Rb connected between it and -Vcc.

Since the circuit consisting of the transistor Qc, the resistor 8, and the diode 10 connected between the collector of the transistor Qb and the +Vcc power supply is a constant current circuit, the current i output to the collector side of the transistor Qb as described above The change in transistor
This is converted into a large voltage change on the collector side of Qb, and from the amplifier Ao to which the input signal having this large voltage change is supplied, a large output signal is sent to the output terminal 5.

FIG. 5 is a chart explaining how to set the operating points of transistors Qa and Qb during no signal, which are required to obtain the maximum output amplitude in the amplifier device of the present invention. , the horizontal axis is the input current and the vertical axis is the output current, where 1 shown on the horizontal and vertical axes indicates the maximum input current and output current, and the voltage of transistors Qa and Qb when there is no signal. By setting the operating point during no signal so that the input current and output current are 1/2 of the maximum input current and output current, the amplifier device of the present invention can output an output with the maximum output amplitude. It is.

The gain characteristic Av(s) of the amplifier device of the present invention is expressed by the following equation (1), where the gain of the amplifier Ai is A(s) and the input impedance of the amplifier Ao is Zi.

Av(s)=A(s)Zi/Ra...(1) Looking at the above equation (1) showing the voltage gain between the input terminal 1 and the output terminal 5 in the amplifier of the present invention, the present invention To configure the amplifier device with the desired voltage gain, the gain A of the amplifier Ai is
(s), input impedance Zi of amplifier Ao, resistance Ra connected to the emitter of transistor Qa
(generally impedance), etc., as required, but even if an amplifier with the desired voltage gain is obtained by the above adjustment, it will immediately This does not necessarily mean that the amplifier device has good output amplitude characteristics.

That is, if we consider the case where, for example, the resistance value of the resistor Ra shown in equation (1) above is set so that the voltage gain of the amplifier device becomes a desired value, in the above case, the resistance value Even if the voltage gain of the amplifier is set as desired by setting Ra, the current values of the input current and output current when there is no signal in that state are shown in Figure 5. It is not necessarily set to a 1/2 state like this.

FIG. 6 is a circuit diagram illustrating a solution to the above-mentioned problem, and FIG. 6 a and FIG. 6 b only show the main parts, and FIG.
In the circuit shown in
One end of the resistor is connected to the emitter of Qa, and the other end of the resistor is connected to the connection point between Zener diode ZD and diode D1. Zener diode ZD between emitter and resistor Ra
is connected.

In either of the circuits a and b in FIG. 6 described above, the value of the current i flowing through the resistor Ra can be variably adjusted by using a Zener diode having an appropriate Zener voltage as the Zener diode ZD. Even if a resistor Ra has a resistance value that allows an amplification device with a voltage gain of Therefore, by using the means shown in FIG. 6, for example, it is possible to easily create an amplifier device of the present invention that has a desired voltage gain and can obtain the maximum output amplitude. can be provided to

As is clear from the above description, the structure of the device according to the embodiment of the present invention shown in the fourth drawing is not only simple in structure, but also has a simpler structure than the conventional device shown in the second drawing. is simple and linear
It is possible to easily configure a high-output amplification device by using an IC for the amplifier Ai, and the device does not use a current mirror circuit, and two transistors Qa and Qb are connected in cascade. Since a current with the same current value flows through the Since the mode of change is opposite for transistor Qa and transistor Qb, they cancel each other out, and therefore, the various problems that occurred due to the use of a current mirror circuit in the conventional device do not occur. Furthermore, since the transistor Qb circuit is a base-grounded amplifier circuit, there is no feedback between the collector and the base. This constitutes an amplifying device that is not easily affected by impedance and has excellent linearity.

The superior linearity of the amplifying device of the present invention will be supplementarily explained with reference to mathematical expressions as follows. In the circuit layout shown in Figure 4, if the mutual conductance of the transistor Qa is gm (Qa), then the transistor Qa and the resistor Ra
The voltage-current conversion system Gm of the circuit is expressed as Gm=gm(Qa)/Ra.gm(Qa)+1...(2) as shown in equation (2) above.

Also, the input/output characteristics K of the circuit of transistor Qb
is the transconductance of transistor Qb gm
(Qb), it is expressed by the following equation (3).

K=Rb.gm(Qb)/Rb.gm(Qb)+1 (3) Therefore, the overall input/output characteristic GmK is expressed by the following equation (4).

GmK={Rb.gm(Qa)}gm(Qb)/{Ra.gm(Qa)+1}
{Rb.gm(Qb)+1} ...(4) The same operating current flows through transistors Qa and Qb, and it changes in opposite directions in both transistors, so 2 in equation (4) above Mutual conductance gm of two transistors Qa, Qb
(Qa) and gm(Qb) change as the current changes so as to cancel each other out, so the overall input/output characteristic shown by equation (4) has excellent linearity.

FIG. 7 is a circuit diagram of another embodiment of the amplifier device of the present invention. In the amplifier device shown in FIG. (voltage change rate per unit time) and a reduction in even-order harmonic distortion. In addition,
In Fig. 7, Qa′, Qb′ are transistors, Ra,
Ra', Rb, and Rb' are resistors, and the transistor Qa' is a transistor having complementary symmetry with respect to the transistor Qa.
Qb' is a transistor having complementary symmetry to transistor Qb. As for the transistors Qa and Qb, transistors having mutually complementary symmetry may also be used.

Transistors having mutually complementary symmetry may also be used.

(Effects) As is clear from the detailed explanation above, the amplifier device of the present invention has a simpler configuration than conventional devices, and uses a linear IC for the amplifier Ai to achieve a high output amplifier device. can be easily configured,
Further, the amplifier device of the present invention does not use a current mirror circuit, and the amplifier device of the present invention uses two transistors Qa and Qb that are connected in cascade.
Even if the value of transconductance changes with the change in the magnitude of the current flowing through the transistor,
Since the mode of change is reversed and canceled by the transistor Qa and the transistor Qb, the various problems caused by using the current mirror circuit in the conventional device can be solved in the amplifier device of the present invention. Furthermore, the amplifier device of the present invention does not suffer from the problem of a decrease in the utilization rate of the power supply voltage, which was a problem with conventional devices, and it is possible to easily provide a large output amplifier device with excellent linearity. be able to.

[Brief explanation of drawings]

1 and 2 are block circuit diagrams of conventional devices, FIG. 3 is a block diagram for explaining the configuration principle and operating principle of the amplifying device of the present invention, and FIG. 4 is a block diagram of the amplifying device of the present invention. FIG. 5 is a curve diagram for explaining the operation, and FIGS. 6 and 7 are block circuit diagrams of other embodiments of the amplifier according to the present invention. Ai, Ao...Amplifier, 1...Input terminal, Z1...Impedance, Qa, Qb...First and second semiconductor active elements, Ra, Rb, Ra', Rb', 2-4, 6-9, R
1 to R3...Resistance, 10,11,D1...Diode, 12,13,ZD...Zena diode.

Claims (1)

[Claims] 1 A third electrode in a first active element comprising at least three electrodes: a base or gate (first electrode), an emitter or source (second electrode), and a collector or drain (third electrode); Or, it has at least three electrodes: a gate (first electrode), an emitter or source (second electrode), and a collector or drain (third electrode), and has a conductivity type different from that of the first active element described above. A constant current circuit or a resistor is connected between the reference potential point and the connection point connecting the second electrode of the second active element having the second active element, and the second electrode is connected to the reference potential point via an impedance. supplying the output signal of the preceding stage amplifier to the first electrode of the first active element configured to constitute a second electrode grounding type amplifier circuit;
Furthermore, the circuit of the second active element described above constitutes a first electrode grounding type amplifier circuit,
Furthermore, an amplifier device is provided in which an output signal is obtained from a circuit on the third electrode side of the second active element described above.