JPS59178804A - Amplifier circuit - Google Patents

Abstract

PURPOSE:To avoid generation of switching distortion by connecting respectively a diode having a fast switching speed to complementary transistors (TR) and allowing the diode to perform switching operation in place of the complementary TRs so as to increase the switching speed. CONSTITUTION:Although diodes D1, D2 are both turned off with an input terminal Ti applied with no input signal, since a current I1 by a current source A1 flows from an NPN TRQ1 and a current I2 by a current source A2 flows to a PNP TRQ2, both the TRs Q1, Q2 are both turned on. Load currents IL, IL' flow alternately to the diodes D1, D2 in response to positive and negative half cycles when an input signal Vi is applied, and a current flows always to the NPN and PNP TRs Q1, Q2. That is, the PNP and PNP TRs Q1, Q2 constituting the complementary TRs do not perform the switching operation but the diodes D1, D2 perform the switching operation instead.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amplifier circuit in which switching distortion tvjf is reduced by k.

Conventionally, as shown in Fig. 1, NPN type transistor and P
An amplifier circuit configured to perform class B operation using a pair of complementary transistors consisting of an NP transistor and an NP transistor is preferred due to its high efficiency. In Fig. 1, Q1 + Q2 are N P N It consists of a so-called complementary type transistor and an f'NP type transistor.
i is both transistor Q1. QzK are commonly connected constant input terminals, and RL is connected to each transistor Q1. A load resistor is commonly connected between the emitter electrode of Q2 and the ground, 1゛0 is the output terminal, Vcc, -VE is the power supply, and each transistor Ql
+Q2 is configured to perform an emitter 7-lower operation.

In the above configuration, the input terminal Ti K input signal Vi
is added, and in the positive half cycle, N P N
' type transistor Q1 turns on and PNPQ transistor Q2 turns off, and in the negative half cycle, PNPQ transistor Q2 turns on.
When the NP type transistor Q is turned on, the NPN type transistor Q1 is turned off, and the NPN and PNP type transistors Ql and Q2 are turned on, respectively, according to the positive and negative half cycles of the human input signal.
By performing switching operations alternately, an output signal Vo f can be obtained from the terminal To.

Incidentally, such amplifier circuits are usually constructed of bipolar transistors, but it is difficult to increase the switching speed due to the characteristics of the elements. For this reason, when applied to audio amplifiers and the like that require large switching speeds, switching distortion is unavoidable.

The present invention has been designed to eliminate the above-mentioned drawbacks, and is configured such that a diode with a high switching speed is connected to each complementary transistor, and the switching operation is performed by the diode instead of the complementary transistor. The amplification circuit provided here is for both C and L purposes. Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a circuit diagram showing an amplifier circuit according to an embodiment of the present invention, and the same parts as in FIG. 1 are designated by the same numbers, and are designated by Dl.

D2 are NPN type transistor Q1 and PNPNP, respectively.
The type transistor Q consists of a series of diodes carved in the emitter electrode and connected in series in the forward direction.
This is a current source connected in series to the emitter electrode of Q2.

In the above configuration, when no human input signal is applied to the input terminal 1'i, both diodes DI+D2 are off, but current ll from the current source A1 flows from the NPN transistor Q1, and the PNPNP transistor Q Because current 12 from current source A2 flows into both transistors Q1. Both Q2 are on.

Next, input terminal TiK input signal V! is applied, in the positive half cycle the diode DI has a load current of ■
L flows, and iL + flows into the NPN transistor Ql.
As Il flows, 1 is applied to PNP type transistor Q2.
2, no current flows through the diode D2. As a result, an output signal VO based on the above IL is output from the terminal To.
is output.

Similarly, in the negative half cycle, the load current L in the opposite direction to the above IL flows through the diode D2, and the NPN
I flows through the type transistor Q1, and IL'+I2 flows through the PNP type transistor Q, but current flows through the diode Dl. is output.

In this way, when the input signal Vi is applied, the diode l)1. Although the load current I'Lw i'L alternately flows through D2, current always flows through the NPN and PNP transistors Ql-Q2.

That is, as a result, the NPN and PNP type transistors Ql + Q2 forming the complementary transistors do not perform a switching operation, and instead the diodes D1 . D2 now performs a switching operation.

In this case, the diodes D, D2 are Nyoto Cyparia diodes or PN with high switching speed.
By using a junction diode, it is possible to reduce isostatic distortion, which allows for faster switching operation.

Also, current source A1. As A2, it is sufficient to use a device with a small current capacity, so it can be done with low power consumption, and by doing so, the amount of heat generated can be kept low, so reliability can be improved.

Further, the current source A1. Instead of A2, NPN and PN
P-type transistor Q1. When no input signal v1 is applied to Q2, substantially NPN transistors Q1 and f'N
This can be achieved by providing a bias source that turns on the P-type transistor Q2yr. Each transistor Q], the base Vr of Q2:, and the above 11. I2
One can add a bias for a small current corresponding to the current.

In this text, we have explained the case where B operation is performed, but the same effect χ can also be obtained by applying it to AB class operation where a small amount of current is passed through the diode to make it work when there is no signal. .

As is clear from the above description, according to the present invention, a diode with a high switching speed is connected to each complementary transistor, and the complementary transistor is depressed so that the switching operation 7 is performed by the diode. , conventional drawbacks can be eliminated.

[Brief explanation of drawings]

FIGS. 1 and 2 are circuit diagrams illustrating conventional and inventive implementations. Ql, Q2...Phase 1 type transistor, RL...Load resistance, DI, D2...Diode, A1+A2...
Current source, 1゛! ...input terminal, To...output terminal,
IL, I'L...Load current.

Claims (1)

[Claims] 1. An NPN transistor and a PNP transistor whose base electrodes are connected to a common input terminal, and a first transistor which is connected in series in the forward direction to the emitter electrodes of the NPN and PNP transistors, respectively. diode and second
a diode, an IC-connected load resistor between the first diode and the second diode, and the ground, and an NPN
and a power supply connected between the respective collector electrodes of the PNP type transistors, a first bias source for turning on the substantially KNPN type transistor r when no signal is input to the NPN and PNP type transistors, and a first bias source connected between the collector electrodes of the PNP type transistors;
When a signal is applied to the common input terminal and tl is constant, the ml diode and the second diode are alternately connected in accordance with the positive and negative half cycles. What is claimed is: 1. An amplifier circuit characterized in that it is configured to perform a neutralizing operation. 2. The amplifier circuit according to claim 1, wherein the first and second diodes are Schottky barrier diodes. 3. The amplifier circuit according to claim 1, wherein the first and second diodes are comprised of 1'N junction diodes.