JPH05110365A - Constant current pulse generating circuit - Google Patents

Abstract

(57) [Summary] [Structure] The transistor Q ₁ to which an input voltage is applied to the base, the current source circuit I ₁ whose output terminal is connected to the emitter of the transistor Q ₁ , and the current of the constant current source circuit I ₁ . And a clamp circuit K connected to the control terminal C, and a first resistor r ₁ connecting the control terminal C for controlling the control terminal and the emitter of the transistor Q _1. The clamp circuit K applies the voltage to the control terminal C. Is configured to limit the applied voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant current pulse generator circuit. More specifically, the present invention relates to a novel configuration of a pulse generation circuit that can generate a current pulse with a biased signal ratio at high speed with low power consumption.

[0002]

2. Description of the Related Art As a pulse generation circuit when a high speed operation is required, a structure in which a differential circuit and a constant current source are combined is generally used. However, the pulse generation circuit having such a configuration is excellent in terms of reliable high-speed operation, but has a drawback that the energy consumption is increased because the energy efficiency is low due to the operation method in which the maximum current always continues to flow. ..

In order to solve such a drawback, there has been proposed a structure in which a capacitor for charging an electric charge is connected to a current path and the capacitor is discharged at the time of high level output. However, such a method inevitably uses a capacitor having a large capacity, and is not suitable for application to an integrated circuit.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the above-mentioned problems of the prior art and to provide a constant current pulse generation circuit having a novel configuration which consumes less current and is suitable for integration. Has a purpose.

[0005]

That is, according to the present invention,
As shown in FIG. 1, a transistor Q ₁ having an input signal V _in applied to its base, a current source circuit I ₁ having an output terminal connected to the emitter of the transistor Q ₁ , and an output current of the constant current source circuit Control terminal C for controlling and the transistor Q ₁
A first resistor r ₁ for connecting the emitter of the
And a clamp circuit K connected to the control circuit C. By regulating the terminal voltage at the control terminal C by the clamp circuit K, the current flowing through the transistor Q ₁ is limited to a predetermined range. A constant current pulse generation circuit is provided.

[0006]

In this circuit, when the input signal V _in is low level, the transistor Q ₁ becomes non-conductive. At this time, the terminal voltage of the control terminal C of the constant current source circuit I ₁ is also low,
Substantially no current flows in the current path formed by the transistor Q ₁ and the constant current source circuit I ₁ .

On the other hand, the input voltage V _in the transistor Q ₁ is turned at a high level, the terminal voltage of the control terminal C of the constant current source circuit I ₁ is increased. Therefore, the current I flows in the current path formed by the transistor Q ₁ and the constant current source circuit I ₁ . However, at this time, the terminal voltage _Vb of the control terminal C does not rise above a predetermined level due to the action of the clamp circuit K connected to the control terminal C of the constant current source circuit I ₁ . That is, an output current I having a value shown in the following equation (1) flows through this constant current pulse generation circuit.

I = I ₀ + (V _in −V _be −V _b ) / r ₁ (1) [where I ₀ is the current flowing through the constant source current source circuit I ₁ and V _be Is the base-emitter voltage of the transistor Q _1. ]

Therefore, if the resistance value of the resistor r ₁ is set sufficiently large, the current value of the output pulse from the constant current pulse generating circuit is regulated to a substantially constant value.

As described above, the constant current pulse generating circuit according to the present invention combines the current path of the type in which a current is supplied only at the time of output and the function of limiting the amount of current at the time of signal output within a predetermined range. It is characterized in that it is configured.

That is, the constant current pulse generating circuit according to the present invention is basically composed of a current path through which a current flows only when the output current is at a high level. Therefore, the current consumption is reduced as compared with the conventional pulse generating circuit including the current path formed by the differential circuit.

Further, in the constant current pulse generating circuit according to the present invention, the generated output current is limited to a predetermined range by the clamp circuit connected to the control terminal of the current source circuit. Therefore, the output level is stable even when the high speed operation is performed.

Further, as will be specifically described later, the constant current pulse generating circuit according to the present invention can be constituted by elements such as a transistor, a diode and a resistor which can be easily integrated. Therefore, it can be advantageously used as a high-speed pulse generation circuit in an integrated circuit.

Hereinafter, the present invention will be described more specifically with reference to examples, but the following disclosure is merely an example of the present invention and does not limit the technical scope of the present invention.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a diagram showing a concrete example of the configuration of a constant current pulse generation circuit according to the present invention.

As shown in the figure, the constant current pulse generating circuit includes a constant current source circuit I including a transistor Q ₂ and a resistor R ₁ and a transistor Q ₁ receiving an input voltage V _in.
And a current path composed of Transistor Q
_A resistor R ₂ is connected between the emitter of _{1 and} the base of the transistor Q ₂ . The base of the transistor Q ₂ is grounded via the diode D ₁ and the resistor R ₃ and is also grounded via the series circuit including the diodes D ₂ and D ₃ . The diode D ₃ constitutes a clamp circuit, and the pair of diodes D ₁ and D ₂ are inserted for temperature compensation of the transistor Q ₂ .

Furthermore, in the circuit shown in FIG.
₄ is inserted between the voltage source and the resistor R _2, and the resistor R ₅ has one end connected to the base of the transistor Q ₂ and the other end grounded. These resistors R ₄ and R ₅ are connected to the input voltage V
_{When in} is at low level, a minute bias current is made to flow through each transistor and diode, or the accumulated charge is discharged, so that high-speed operation of the circuit can be made more reliable.

The circuit configured as above is already shown in FIG.
Since the same operation as that described above is performed, detailed description of the operation will be omitted, but as shown in FIG. 2, all are configured by elements that can be integrated.

When h _{fe of the} transistor Q ₂ used in the current source circuit I is low, this portion may be formed by a Darlington circuit.

[0020]

As described above, the constant current pulse generating circuit according to the present invention has a structure that consumes current only at the time of output, and is capable of high speed operation. Further, since this constant current pulse generation circuit can be configured by all the elements that can be integrated, it can be advantageously used as a high-speed pulse generation circuit incorporated in the integrated circuit.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a constant current pulse generation circuit according to the present invention.

FIG. 2 is a diagram showing a specific configuration example of a direct-coupled amplifier circuit according to the present invention.

[Explanation of symbols]

D _{1 to} D ₃ diode, I, I ₁ current source circuit, K clamp circuit, Q ₁ , Q ₂ transistor, R _{1 to} R ₅ , r ₁ , r ₂ resistance

Claims (1)

[Claims] 1. A transistor having an input signal applied to its base, a current source circuit having an output terminal connected to the emitter of the transistor, a control terminal for controlling the output current of the constant current source circuit, and an emitter of the transistor. And a clamp circuit connected to the control terminal, and the terminal voltage at the control terminal is regulated by the clamp circuit so that the current flowing through the transistor is limited to a predetermined range. A constant current pulse generating circuit characterized in that