JPH03255708A - Transistor amplifier circuit with mute function - Google Patents

Abstract

PURPOSE:To integrate a muting circuit and a transistor amplifier by utilizing a level corresponding to the non-muting state of a muting signal as the bias potential of a transistor. CONSTITUTION:When a muting signal B is set at a low level, a base current is not supplied to a transistor Q10. Therefore, since the transistor R10 is turned to an OFF state, a load 4 is turned to a muting state without supplying the signal current. In such a state, a signal A to be amplified is biased through a coupling capacitor C10 and a bias resistor R10 into the generator of the muting signal B. On the other hand, when the muting signal B is set at a high level, the base current is supplied to the transistor Q10 and therefore, the bias is applied to a transistor circuit 5. In such a state, the signal A to be amplified is amplified by the transistor circuit 5 and supplied to the load 4.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention has an amplification function and a muting function,
This invention relates to a transistor amplifier circuit with a muting function that has a small number of parts and is used in commercial equipment, industrial equipment, etc.

BACKGROUND OF THE INVENTION FIG. 2 shows the configuration of a conventional transistor amplifier circuit with a muting function. This transistor amplifier circuit with a muting function includes a switching circuit 1 consisting of an analog switch ICI, a transistor amplifier circuit 2 consisting of a coupling capacitor C1, a bias resistor R1, a series feedback resistor R2, a transistor Q1, a voltage dividing resistor R3, and a voltage dividing circuit 2. Resistance R
4, a muting circuit 3 consisting of a pull-up resistor R5, a transistor Q2, and a transistor Q3.

Further, A is an amplified signal, B is a muting signal having a binary level of 0V level (low level) and 5V level (high level), and 4 is a load.

Next, the operation of the above conventional example will be explained. When the muting signal B is low level, the analog switch IC
When I is turned off, transistor Q3 is turned off, and transistor Q2 is turned on, so that transistor Q1 is turned off, resulting in a so-called muting state.

On the other hand, when the muting signal B is at a high level, the analog switch ICI is turned on, the transistor Q3 is turned on, and the transistor Q2 is turned off, so that the muting circuit 3 receives electricity from the transistor amplifier circuit 2. be separated from each other.

In this state, the transistor Q1 is brought into a self-biased state, and the amplified signal A is amplified by the transistor amplifier circuit 2 and introduced into the load 4.

Incidentally, it is desired that the area occupied by the transistor amplifier circuit with a muting function on the substrate be small. It is also desired that the configuration be simple and reliable. High-density mounting is easy, making it smaller and lighter, and
This is because it is possible to reduce costs.

Problems to be Solved by the Invention However, the above-mentioned conventional transistor amplifier circuit with muting function occupies a large area on the board due to the large number of components, and it is possible that multiple transistor amplifier circuits with muting function may be used in one device. Since they are often provided individually, it becomes difficult to implement high-density packaging, which has the drawback that it is impossible to reduce the size, weight, and cost of the product.

The present invention solves these conventional problems,
It is an object of the present invention to provide a transistor amplifier circuit with a muting function in which a muting circuit and a transistor amplifier circuit can be integrally configured and the number of parts is reduced.

Means for Solving the Problems In order to achieve the above object, the present invention provides a system in which a muting signal and an amplified signal, which are binary signals, are input and the level of the binary signal is at a level corresponding to a non-muting state. At some times, this level is used as a bias potential for the transistor circuit to amplify the signal to be amplified, while at other times, when the level of the binary signal is at a level corresponding to the muting state, this level is used to turn off the transistor circuit. It is configured so that it can be used as a state.

Therefore, according to the present invention, when the muting signal, which is a binary signal, is at a level corresponding to the muting state, the transistor circuit is turned off and enters the so-called muting state, and the muting signal is turned off. When the level corresponds to the muting state, the transistor circuit is biased and is in a state where it can amplify the signal to be amplified, and the muting signal itself can bias the transistor circuit, simplifying the transistor circuit. It has the effect of reducing the number of parts.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, 5 is a transistor circuit, including a coupling capacitor CIO, a bias resistor R10, and a transistor QI.
0 and a series feedback resistor R11. The coupling capacitor CIO passes the alternating current component of the amplified signal A and introduces it into the base terminal of the transistor QIO. Bias resistor R10 connects muting signal C to transistor Q1
0 base terminal. 4 is a load of the transistor circuit 5.

Here, the muting signal C is a binary signal having a "low level" corresponding to a muting state and a "high level" corresponding to a non-muting state. Note that the output impedance of the muting signal C generator (not shown) is desirably low impedance.

Next, the operation of the above embodiment will be explained.

When muting signal C is “low level”,
No base current is supplied to transistor QIO. Therefore, since the transistor QIO is turned off, no signal current is supplied to the load 4, resulting in a so-called muting state.

In this state, the amplified signal A is connected to the coupling capacitor CI
O, muting signal C through bias resistor R10
generator (not shown).

On the other hand, when the muting signal C is at "high level", this "high level" voltage and bias resistor RI
O, pace-emitter voltage vB of transistor QIO
E, and the base current determined by the series feedback resistor R11 is supplied to the transistor QIO, so that
A bias is applied to the transistor circuit 5.

Therefore, in this state, the amplified signal A is amplified by the transistor circuit 5 and supplied to the load 4.

In this manner, according to the above embodiment, the muting signal C itself supplies the pace voltage to the transistor QIO through the bias resistor RIO, so that the muting signal C biases the transistor Q10. Therefore, a transistor amplifier circuit with a muting function can be configured with only four components, which has the effect of reducing the number of components.

Effects of the Invention As is clear from the above embodiments, the present invention sets the level corresponding to the non-muting state of the muting signal, which is a binary signal having levels corresponding to the muting state and the non-muting state, to the transistor bias. By using this as a potential, a muting circuit and a transistor amplifier are integrated. Therefore, it has the following effects.

That is, by reducing the number of components, the area occupied by the transistor amplifier circuit with muting function on the substrate can be reduced. Furthermore, since the number of parts can be reduced, the mean time between failures (MTBF) is increased and reliability is increased. Furthermore, it has the excellent effect that high-density packaging is facilitated, and a device using this transistor amplifier circuit with a muting function can be made smaller and lighter, as well as cost reduction.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a transistor amplifier circuit with a muting function according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional transistor amplifier circuit with a muting function. 5...Transistor circuit, QIO...Transistor, RIO...Bias resistor, R11...Series feedback resistor, C10...Coupling capacitor. Figure 1

Claims (1)

[Claims] When a binary signal and an amplified signal having a level corresponding to a muting state and a level corresponding to a non-muting state are input, and the binary signal is at a level corresponding to a muting state, an off state is established. and when the binary signal is at a level corresponding to a non-muting state, a transistor circuit with a muting function is provided with a transistor circuit that is biased by a level corresponding to the non-muting state and amplifies the signal to be amplified. Amplification circuit.