JPS59226507A - Amplifying device - Google Patents

Abstract

PURPOSE:To obtain an amplifying device of a large output, which is excellent in its linearity by a simple constitution, by cascading two active elements whose conductive type is different from each other, and connecting a constant-current circuit or a resistance between its connecting point and a reference potential point. CONSTITUTION:An input impedance of a circuit of a transistor Qa is extremely small, and also, a current amplification factor alpha of a circuit of the transistor Qa is about 1. Accordingly, an output signal of voltage Vo from an amplifier Ai is applied to the emitter of the transistor Qa as a current of a current value of (i)=Vo/Z1 through an impedance Z1 connected to the emitter of the transistor Qa, and supplied to the emitter of a transistor Qb from its collector. A circuit of the transistor Qb constitutes a base ground type amplifying circuit, therefore, as to a current flowing to the collector side of the transistor Qb, too, its current value becomes (i).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to an amplifying 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 amplification devices that can obtain high-output signals with high fidelity.
It is well known that various types of amplification devices have been provided in the past.

FIG. 1 is a block diagram showing the basic configuration of an amplifier currently most commonly used as an amplifier constructed using individual parts.
1 is an input terminal, Q1 to Q9 are transistors, CC is a constant current source circuit, 1 to 4 are resistors, E1 to E3. +Vcc, -V
cc is a power supply, AO is an amplifier (normally, a power amplifier with a gain of l is used as the amplifier Ao), 5 is an output terminal, and the amplifier shown in the first diagram includes transistors Ql and Q2.
and a differential amplifier circuit composed of a constant current source circuit CC and resistors 2 and 3, etc., and a differential amplifier circuit composed of a -current mirror circuit of transistors Q7 to Q9, a resistor 4, transistors Q3 to Q6, etc., Amplifier A with a gain of 1
It is composed of.

In the amplifier device shown in the first diagram, transistors Q3゜Q4
circuit, and transistor Q5. Q6 circuit, as well as transistor Q8. The circuits such as Q9 are each constructed as a cascode amplifier circuit (■).

This prevents deterioration of signal linearity when the amplitude is large.

The conventional amplifying device shown in FIG. Since the existence of such components reduces 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 device, and there has been a desire to improve this problem.

FIG. 2 is a block diagram of another example of the configuration of the conventional amplifier device. In FIG. input (No. 8 is amplified by amplifier At, and then connected to transistor QIO, which constitutes a common-base type amplifier circuit)
is supplied to the emitter of via a resistor R1.

As is well known, the input impedance of a common base type amplifier circuit is extremely low, so if the voltage of the output signal of the amplifier At is Vo, the magnitude of the signal current i supplied to the emitter of the transistor QIO via the resistor R1 is is 1=
Although expressed as Vo/R1, the output signal current from the collector of the transistor QIO constituting the common base amplifier circuit is also i.

The output signal current i of the transistor QIO forming the common base amplifier circuit is amplified via the transistors Qll-Q13 forming the current mirror circuit.
It is given to the input side circuit of Ao.

By the way, since the input side circuit of the amplifier Ao is provided with the constant current source circuit CCI, there is a large voltage change on the input side of the amplifier AO corresponding to the output signal i appearing via the current mirror circuit. A signal indicating this is generated. In addition, in FIG. 2, R2 and R3 are correction resistors, and E4.
E 5 is a power supply, and transistor Q in the current mirror circuit 12. Q13 constitutes a cascode amplifier circuit.

In the amplifier device shown in the second diagram, the signal current i, which is supplied via the resistor R1 to the emitter of the transistor QIO constituting the common base amplifier circuit by the output signal of the amplifier Ai, is raised to a high level via the current mirror circuit. Since it is applied to the impedance circuit and converted into a large voltage change there, for example, even if a linear IC that cannot generate a large output signal voltage is used as the amplifier Ai, a large signal voltage can be obtained at the input side of the amplifier Ao. It is possible,
Therefore, the amplifier device having the configuration shown in the second figure is
This circuit has the advantage of being able to easily provide a high-output amplifier with a circuit configuration with a small number of parts, and can be said to be an economically superior circuit.

However, the amplifier device shown in FIG. 2 has transistors Q11. Q
In addition, the signal voltage generated in the correction resistors R2 and R3 may cause deterioration of high frequency characteristics through parasitic capacitance, etc. There were problems such as a worsening of the power utilization rate on the negative side due to its existence, and improvement of this problem was desired.

(Means for Solving the Problems) The present invention comprises at least 3W & poles: a base or gate (first electrode), an emitter or source (second electrode), and a collector or drain (third electrode). the third electrode of the first active element, the base or gate (11th! pole), and the emitter or source (second electrode)
and a collector or drain (third electrode), and a second electrode of a second active element having a conductivity type different from that of the first active element. and a reference potential point, a constant current circuit or a resistor is connected, and the output signal of the preceding stage amplifier is supplied to the second electrode of the first active element via an impedance. , both the circuit of the first active element and the circuit of the second active element constitute a first electrode grounding type amplifier circuit; The present invention provides an amplifier device in which an output signal can be obtained from a circuit on the third electrode side of an active element.

(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 and 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 At and then applied to the second electrode of the first semiconductor active element Qa via the impedance Z1.

In the illustrated example, the first semiconductor active element Qa described above
Although transistors having different conductivity types are used as the second semiconductor active element Qb, which will be described later, in this specification, transistors are used as the first and second semiconductor active elements. Regarding each electrode in each of the transistors Qa and Qb, the base is sometimes called a first electrode, the emitter is sometimes called a second electrode, and the collector is sometimes called a third electrode.

In addition, 1. As the second semiconductor active elements Qa, Qb,
Field effect transistors (F
In the case where the amplifying device of the present invention is configured using the ET), the first. Second semiconductor active element Qat Qb
Needless to say, the first electrode corresponds to the gate, the second electrode corresponds to the source, and the third electrode corresponds to the drain.

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

In the amplifier shown in FIG. 3, the circuit of the transistor Qa constitutes a common base type amplifier circuit, so the input impedance of the circuit of the transistor Qa is extremely small, and the current amplification factor α of the circuit of the transistor Qa is approximately 1. It is.

Therefore, the output signal of voltage Vo from amplifier Ai is
A current with a current value of i = Vo/Z 1 is applied to the emitter of the transistor Qa through an impedance Zl connected to the emitter of the transistor Qa, so that a current value flows from the collector of the transistor Qa to the emitter of the transistor Qb. A current of i is supplied.

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. A current can be generated in the collector circuit of transistor Qb.
It is clear that if a constant current circuit is connected to the collector circuit of transistor Qb, a large voltage change will occur in the collector circuit of transistor Qb as the current i changes.

The amplifier device of the present invention shown in FIG. As is clear from a comparison with the conventional device shown in FIG. 2, the amplifying device of the present invention has a simpler configuration than the conventional device shown in FIG. The configuration is simpler than that of the present invention, and a high-output amplifier can be easily constructed by using a linear IC as the amplifier At.Furthermore, the amplifier of the present invention does not use a current mirror circuit. In addition, in the amplifier device of the present invention, even if the mutual conductance value of the two cascade-connected transistors Qa and Qb changes with a change in the magnitude of the current flowing through the transistors, the mode of the change is Since the transistors Qa and Qb are opposite to each other and cancel each other out, the problems that have arisen due to the use of current mirror circuits in conventional devices do not occur in the amplifier device of the present invention. Furthermore, the amplifying device of the present invention does not suffer from the problem of reduced utilization of power supply voltage, which has been a problem with conventional devices.

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.
is an output amplifier with a gain of 1, for example, and in FIG. 4, Qa, Qb, Qc are transistors, Ra, R
h.

6 to 9 are resistors, to and ti are diodes, 12.13
is a Zener diode, 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 the device is configured to operate at a relatively low operating voltage, as in case C, the power supply +Vccv has a voltage value higher than the operating voltage of the amplifier Ai described above.
This is a power supply circuit used to generate the operating voltage of the amplifier Ai from -Vcc.

In the amplifier shown in FIG. 4, the signal applied to the input terminal 1 is amplified by the amplifier Ai and supplied to the emitter of the transistor Qa via the resistor Ra. 5 The signal applied to the emitter of the transistor Qa described above is , amplifier A
If the voltage of the output signal from i is Vo, the input impedance of the circuit of the transistor Qa constituting the common base type amplifier circuit is extremely low as described above. The current i flowing into the emitter of is expressed as 1=Vo/Ra, and as mentioned above, the current amplification factor α of the transistor Qa of the common base type amplifier circuit is approximately 1, so the transistor from the collector of a of transistor Qb
The current flowing into the emitter of is i.

In the amplifier shown in FIG. 4, +Vcc power supply and -Vea
Transistor Qc and resistor 8 provided between the l source
．． A circuit consisting of a diode 1o, etc., and a transistor Qb
, the resistor Rh, and the diode 11, including the resistor 9, each constitute an individual constant current circuit.

By the way, transistor Qb, resistor Rh, and diode 1
1 (including the circuit of the diode 1o and the resistor 9), the base of the l transistor Qb has the diode 10 and the resistor 9 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 with the diode 11.

Therefore, the circuit of transistor Qb essentially operates as a common base type amplifier circuit, and its input impedance is extremely small, so that 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 the power supply -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 is output to the collector side of the transistor Qb as described above. A change in the current i is converted into a large voltage change on the collector side of the transistor Qb, and the amplifier Ao, which is supplied with the signal having this large voltage change, outputs a large output signal to the output terminal 5. is sent out.

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 l shown on the horizontal and vertical axes indicates the maximum input current and output current, and the transistor Q when there is no signal.
By setting the no-signal operating point so that the input current and output current of The output can be extracted.

The gain characteristic Av(s) of the amplifier device of the present invention is the amplifier At
When the gain of Ao is A(s) and the input impedance of the amplifier Ao is Zi, the following equation (1) is obtained.

1 AV(5)=A(8) −・= (1)a Looking at the above equation (1) indicating the voltage gain between the input terminal 1 and the output terminal 5 in the amplifier device of the present invention, the present invention In order to configure the amplifier with the desired voltage gain, the gain A(s) of the amplifier A+, the input impedance Zj of the amplifier Ao, and the resistor Ra connected to the emitter of the transistor Qa (generally It can be seen that it is only necessary to adjust the parameters such as impedance) as required, but even if an amplifier having the desired voltage gain is obtained by the above adjustment, it will immediately have good output amplitude characteristics. It does not necessarily mean that it is an amplification device.

That is, now, for example, the resistance R shown in the above equation (1) is adjusted so that the voltage gain of the amplifier device becomes a desired value.
Considering the case where the resistance value of a is set, even if the voltage gain of the amplifier is set as desired by setting the resistance Ra in the above case, the input current and output when there is no signal in that state The current value and the current value are not necessarily set to 1/2 as shown in FIG.

FIG. 6 is a circuit diagram illustrating a solution to the above-mentioned problem. Only the main parts are shown in FIG. 6(a) and FIG. 6(b). In the circuit shown in FIG. 6(a), the base of the transistor Qa is connected to the connection point between the Zener diode ZD and the diode D1, and the circuit shown in FIG. 6(b) In the circuit, a Zener diode ZD is connected between the emitter of the transistor (l) and the resistor Ra.

In both of the circuits shown in FIGS. 6(a) and 6(b), the value of the current i flowing through the resistor Ra can be variably adjusted using a Zener diode having an appropriate Zener voltage as the Zener diode ZD. Therefore, even if a resistor Ra with a resistance value that allows an amplification device with a desired voltage gain is used, a current with a current value as shown by 1/2 in FIG. 5 will flow through the resistor Ra. Therefore, by using means such as shown in FIG. can be easily provided.

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 a high-output amplification device can be easily configured by using a linear IC in the amplifier AI, and
No current mirror circuit is used in the device, and
Since the same current value flows through the two cascade-connected transistors Qa and Qb, the mutual conductance value of the two transistors Qa and Qb, which have complementary characteristics, is the magnitude of the current flowing through the transistors. Even if it changes with the change, the mode of the change is the transistor Qa.
and transistor Qb are opposite to each other, so they cancel each other out. Therefore, the various problems that have arisen due to the use of a current mirror circuit in the conventional device do not occur, and furthermore, the problems in the conventional device do not occur. Furthermore, since the transistor Qb circuit is a base-grounded amplifier circuit, it is not easily affected by the feedback impedance between the collector and the base, and the linearity is improved. It constitutes an excellent amplification device.

The superior linearity of the amplification device of the present invention will be supplementarily explained with reference to mathematical expressions as follows. In the circuit arrangement shown in FIG. 4, if the mutual conductance of the transistor Qa is gm(Qa), then the voltage-current conversion coefficient G+n of the circuit of the transistor Qa and the resistor Ra is expressed by the above equation (2).

Further, the input/output characteristics of the circuit of transistor Qb are expressed by the following equation (3), where gm(Qb) is the mutual conductance of transistor Qb.

Therefore, the overall input/output characteristic G m K is as follows (4)'
It will be as shown by the formula.

The same operating current flows through the transistors Qa and Qb, and changes in opposite directions in both transistors, so the two transistors Q in equation (4) above
The mutual conductance of a, Qb gm(Qa), gm(
Qb) change so as to cancel each other out as the current changes, so the overall input/output characteristics shown by equation (4) are excellent or have nearness.

FIG. 7 is a circuit diagram of another embodiment of the amplifier device of the present invention. In the amplifier device shown in FIG. 7, the circuit portion between the amplifiers Ai and Ao is made into a push-pull connection circuit.
Improved slew rate (voltage change rate per unit time),
This makes it possible to reduce even-order harmonic distortion. In FIG. 7, Q a'#Q b' is a transistor, transistor Qa' is a transistor having complementary symmetry to transistor Qa, and transistor Qb' is a transistor having complementary symmetry to transistor Qb. It is a symmetrical transistor. As for the transistor Qa and the transistor Qb, 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 the conventional device, and
A linear IC can be used in the amplifier Ai to easily configure a high-output amplifier, and the amplifier of the present invention does not use a current mirror circuit, and the amplifier of the present invention does not use a cascade circuit. Even if the mutual conductance values of the two connected 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. Therefore, the various problems that occurred due to the use of a current mirror circuit in the conventional device 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 was a problem in the above, does not occur, and it is possible to easily provide a high-output amplifier with excellent linearity.

[Brief explanation of the drawing]

1 and 2 are block circuit diagrams of conventional devices, respectively, and FIG. 3 is a block diagram for explaining the configuration principle and operating principle of the amplifier device of the present invention. Further, FIG. 4 is a block circuit diagram of an embodiment of the amplifier device of the present invention, FIG. 5 is a curve diagram for explaining the operation, and FIGS.
The figure is a block circuit diagram of another embodiment of the amplifier device of the present invention. A i p A o...Amplifier, l...Input terminal 1
, zl... Impedance, Qa, Qb... 1st.
Second semiconductor, body active element, Ra, Rh, 2-4.6-9
．． R1 to R3--Resistance, 10, 11. DI...Diode, 12, 13. ZD...Zena diode,

Claims (1)

[Claims] 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); Gate (first electrode)
and a second active element, which has at least three electrodes: 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. A constant current circuit or a resistor is connected between the connection point where the second electrode is connected to the reference potential point, and the output signal of the previous stage amplifier is connected to the second electrode of the first active element via an impedance. furthermore, both the circuit of the first active element and the circuit of the second active element constitute a first electrode grounding type amplifier circuit. and furthermore, an amplifier device in which an output signal is obtained from the circuit on the third electrode side of the second active element described above.