JPS6029226Y2 - amplifier circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amplifier circuit composed of an integrated circuit and external transistors.

An object of the present invention is to provide an amplifier circuit that operates with low voltage and low power consumption.

Another object of the present invention is to protect the integrated circuit from overvoltage and overcurrent by providing an external power amplification stage.

As shown in Figure 1, conventional low-voltage amplification circuits use individual components, transformers, etc., so although they are relatively efficient, they can be miniaturized due to the transformers, etc. It was difficult.

In addition, a circuit system that has been widely used in the past includes the circuit shown in Figure 2, but in this system, the transistor performs class A operation, so the efficiency is theoretically 50%, but in reality. Efficiency of only about 20 to 30% could be expected, making it extremely difficult to achieve low power consumption, and since other problems such as heat dissipation occurred, a lot of time was wasted on countermeasures, making it uneconomical and unreasonable. .

The present invention eliminates such drawbacks, and by applying common feedback to the voltage amplification stage integrated into an integrated circuit and the class B power amplification stage using complementary transistors provided externally, the circuit is integrated into a single circuit, and the load is reduced. Because it drives directly, there is no need for a transformer, etc., making it possible to downsize.

The present invention will be explained below using figures.

FIG. 3 is a diagram showing an embodiment of the present invention, in which 55PNP
It is characterized by the use of an inverted complementary B-type power amplification circuit composed of transistors (55NPN) transistors, and has a greater power amplification effect than the power amplification circuit shown in Figure 2, so the open loop of the circuit The gain can be increased, and therefore a large amount of N
It becomes possible to apply FB, and the characteristics of the amplifier circuit can be improved.

The input signal is amplified by an integrated voltage amplification stage composed of an inverter 52, a 53P channel MOS transistor that drives a 56NPN transistor, a 54N channel MOS transistor that drives a 55PNP) transistor, and a 55PNP) transistor and a 56NP transistor.
N) A signal in phase with the input can be obtained at the base of the transistor.

This signal is power amplified by an inverted complementary class B amplifier stage consisting of 55 PNP transistors and 56 NPN transistors, and the amplified signal is applied to a 58 load.

Furthermore, 51 and 52 are feedback circuits using channel resistances of MOS transistors, and each of them may be replaced with a resistor.

In integrated circuits with a C-MO3 structure, spike voltages that occur when driving a dielectric load such as a speaker can cause problems such as element latch-up, which can lead to problems such as circuit malfunction and destruction. However, this can be prevented by adding an external driving transistor as in the present invention, which also serves as a protection circuit.

Furthermore, as shown above, since the PNP, NPN) transistor is driven by a MOS transistor whose source is directly connected to the power supply, operation at a low voltage is possible.

Therefore, it is very effective when applied to amplifier circuits that operate at low voltage, especially alarm circuits for watches, hearing aids, etc.
It is useful when applied to devices that require low voltage, low power consumption, and miniaturization.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a conventionally used amplifier circuit. 11...Transistor, 12...Input transformer, 13...Output transformer. FIG. 2 is a diagram showing another example of a conventionally used amplifier circuit. 21...Transistor, 22...Output transformer, 23...Load. FIG. 3 is a diagram showing an embodiment of the amplifier circuit according to the present invention. 51...Input resistance, 52...C-MO
S inverter, 53...P channel MOS transistor, 54...N channel MOS transistor, 55...PNP bipolar transistor, 56...PNP bipolar transistor, 57 ...Output capacitor, 58...
...Load, 59...Feedback resistance.

Claims (1)

[Claims for Utility Model Registration] From a transistor group in which a C-MOS inverter, a first MOS transistor, and a second MOS transistor are integrated, and an external bipolar transistor group in which a PNP transistor and an NPN) transistor are externally attached. inputting an input signal to the gate of the C-MOS inverter, inputting the drain output of the C-MOS inverter to the gate of the first MOS transistor and the second MOS transistor, respectively; The drain output of the first MOS transistor is
into the base of the PN transistor, the second MO
S) Input the drain output of the transistor into the base of the NPN transistor, connect the collector of the PNP transistor to the collector of the NPN transistor to form an output terminal, and send the output signal of the output terminal to the transistor through the resistive element. −
An amplifier circuit characterized by feeding back to the gate of a MOS inverter.