JPS583405A - Dual complementary symmetrical class b amplifier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a dual-complementary symmetrical class B power amplifier, and more particularly to an improvement in such an amplifier. This relates to the reduction of crossover distortion that exists in

Conventional dual-complementary symmetric B, class power amplifiers have undesirable and undesirable performance, both in terms of efficiency and in terms of input signal and reproduction quality.

Dual complementary,! ! Regarding the symmetrical 8-volt power booster, we list many documents on it! An example is the United States, which is so well known to those skilled in the art that there is no need to do so.

There are patent Nos. 33744414 and 39'00790.

The present invention aims to mimic the characteristics of a dual-complementary symmetrical class B power amplifier by adding a low-impedance amplifier between its output stage and the amplifier connected to a signal source (typically an audio frequency signal source). It is proposed to insert a voltage amplifier into the class 8. "Dead bands" associated with amplification are significantly reduced. Additional internal feedback in the output stage of the B-voltage amplifier reduces non-linearity and stabilizes the gain associated with over-the-line voltage feedback. DC feedback maintains the output voltage at the desired level.

By inserting the voltage amplifier, the input impedance of the dual complementary symmetric ELL amplifier becomes a very low AC impedance, the "dead band" is significantly reduced, and the The margin necessary to prevent simultaneous conduction is ensured.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

Referring to FIG. 1, it includes a drive stage and has an input terminal 11 connectable to a suitable signal source, for example an audio signal source;
A dual complementary symmetrical class B power amplifier 10 is shown having an output terminal connected across a receiver 41.

In the left half of FIG.
4 and a voltage amplification transistor 36 having emitter, base and collector electrodes 37, 38 and 39. Also shown in the right half are a first pair of transistors 28 and 32 and a second pair of transistors 20 and 24, which are connected in a dual complementary manner.

Transistor 20 includes emitter, base and collector electrodes 21, 22 and 23, transistor 24 includes collector, base and emitter electrodes 25, 26 and 27, and transistor 28 includes emitter, base and collector electrodes 28, 29 and 3°. The transistor 32 also includes emitter, base and collector electrodes 33, 34 and 35.
Contains. The conduction types of transistors 20 and 28 and the conduction types of transistors 24 and 32 are opposite to each other.

The base electrode 15 of the transistor 14 is connected to the input terminal 11 through the capacitor 12 and the resistor 13. The base electrode 15 is also connected to a ground point through a parallel circuit of a resistor 18 and a capacitor 19. transistor 14
The emitter electrode 16 of the transistor 14 is connected to a ground point, and the collector electrode 17 of the transistor 14 is connected to the positive power supply terminal 40 through resistors 43, 44 and 45.

The collector electrode 39 of the transistor 36 is connected to the transistor 2
It is connected to the connection point between the base electrode 30 of No. 8, the resistors 43, and 44. Base electrode 3 of transistor 36
8 is connected to the connection point between resistors 45 and 44,
Further, the emitter electrode 37 is connected to the base electrode 34 of the transistor 32 and the collector electrode 17 of the transistor 14.

The collector electrode 31 of the transistor 28 is connected to the positive power supply terminal 41 through a resistor 47 and directly to the base electrode 22 of the transistor 20 .

Emitter electrode 29 of transistor 28 is connected directly to emitter electrode 33 of transistor 32, through a resistor 49 and capacitor 51 to ground, and through resistor 48 to collector electrodes 23 and 25 of transistors 20 and 24.

The collector electrode 3'5 of the transistor 32 is connected directly to the base electrode 26 of the transistor 24 and through a resistor 46 to ground. Emitter electrode 33 of transistor 32 is connected to transistors 20 and 24 through resistor 48.
are connected to collector electrodes 23 and 25 of.

The emitter electrode 21 of the transistor 20 is connected to the positive terminal 40, and the collector electrode 23 is connected to the receiver 41 through a capacitor 52.

The collector electrode 25 of the transistor 24 is connected to the transistor 2
This connection point is connected to the receiver 41 through the capacitor 52 and to the base electrode 15 of the transistor 14 through the resistor 50 as described above. Emitter electrode 27 of transistor 24 is connected to ground.

- 13 Resistance 12 kΩ 18 Resistance 100 kΩ 43 Resistance 12 kΩ 44 Resistance 2.2 to 0 45 Resistance 4.7 to Ω 46 Resistance 330 kΩ 47 Resistance 330 k0 48 Resistance 33 kΩ 49 Resistance 12 kΩ 50 Resistance 51JOkΩ 19 Capacitor 22p l"14 Transistor BC2390 2G) Transistor 2N 600324 5>Raster 2N6012 28 Transistor 2N 6012 32 Transistor 2N 6003 36 Transistor 2N8012 In FIG. 2, the voltage amplifying transistor 36 in FIG. The resistor 64 is equivalently represented as a resistor 64 in a voltage divider circuit, and both ends of the resistor 64 are connected to base electrodes 57 and 61 of transistors 55 and 59, which correspond to transistors 28 and 32 in FIG. Although transistor 55 is shown as having emitter, base and collector electrodes 56, 57 and 58, and transistor 59 is shown as having emitter, base and collector electrodes 60, 61 and 62. The relationship with the explanation of FIG. 1 will be obvious.

FIG. 3 shows a typical known form of a drive circuit for a dual complementary symmetrical class B power amplifier, in which a transistor 70 with emitter, base and collector electrodes 71, 72 and 73 is shown. , a transistor 74 having emitter, base and collector electrodes 75, 76 and 77, and a pair of resistors 7B and 79 are connected as shown.

The impedance of the equivalent circuit represented by the resistor 64 in FIG. 2 is calculated by the formula % a 4oo in 4a, LL in 5.00
For an audio amplifier of 0, Rs (reference mark @44) - 2,2 kΩ, R1 (reference mark 45) - 4,7 kΩ, B-2'-1, Rs -2'032.2 to Ω. Since it is Ω, the equivalent impedance is calculated as.

The above low equivalent impedance is an approximation of a cross-circuit circuit. As a result, the "dead band" of the power amplifier was reduced by a factor of 4 - in the example a reduction from 1.2v to 0.3v was achieved.

The embodiment of FIG. 1 further includes internal DC feedback, i.e., collector 23 of transistor 20
AC junction grounding is performed by a circuit extending from collector 25 of No. 4 through resistors 48 and 49 and capacitor 51 to a grounding point.

This is determined by the values of resistors 48 and 49, which is approximately 3.7
This has the effect of stabilizing the voltage gain of 5, reduces the required voltage of the signal applied from the input stage, and reduces the non-direct logic associated with class B amplification. This action occurs before the overall feedback through resistors 50 and 18 is activated.

Using the components listed in the table above - the resulting amplifier gain is 46x (>34dB) and the DC output voltage is 4V, which is essentially the same peak power as a typical 8.5V power supply. It was confirmed that the peak output voltage was generated.

It will be understood by those skilled in the art that various modifications may be made to the illustrated embodiments without departing from the scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an audio frequency power amplifier according to an embodiment of the present invention. FIG. 2 is a diagram equivalently showing the driving path in FIG. 1. 3rd rj! J is a diagram showing a drive circuit in a known amplifier. 11... Input terminal, 14... Signal amplification transistor. 20.24.28.32...Dual complementary symmetrical connection transistor, 36...Voltage amplification transistor. 41...Receiver (load) Patent applicant Telex Communications, Inc.

Claims (1)

[Claims] The present invention includes first and second current control means of mutually opposite conduction type. , an output stage having an input terminal and an output terminal connected to a common load; an input stage including current control means and having an output terminal and an input terminal; Said first and second
dual complementary circuit means for connecting to the input terminal of the current control means; circuit means for connecting the signal source to the input terminal of the input stage; Symmetrical class 8 amplifier.