JPS5821919A - Pulse amplifying circuit - Google Patents

Abstract

PURPOSE:To obtain a sharp output pulse voltage waveform, by using an up- switching element to a field effect transistor and a down-switching element to a bipolar transistor respectively. CONSTITUTION:When the input voltage Vi of a high level is applied to an input terminal 1 at the time t1, the base voltage of a down-transistor TRQd increases to turn on the TRQd. Thus the gate voltage of an up-MOST.Qu is set at a ground level. When the voltage Vi has a fall at the time t2. The base voltage of the TRQd is dropped down to the ground level to turn off the TRQd. Thus a current (C) flows to charge the collector-emitter output capacity Cc of the TRQd. As a result, the TRQd is turned on at the time t3 and a current (B) charges the negative capacity Co of a display device. In this case, the output capacity Cc of a bipolar transistor is small, and accordingly the rise time constant of the output pulse voltage Vo is reduced down to 1/16-1/12. Thus the waveform of the voltage Vo becomes sharp.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to pulse amplification, display devices such as plasma displays (hereinafter abbreviated as 1'DP) and electroluminescent devices (hereinafter abbreviated as KL), etc. Voltage pulse amplification circuits are often used to drive loads.

Conventionally, a pulse amplification circuit used to drive the above-mentioned display device is shown in FIG. 1, for example. That is, this is the first switching element Qu
(hereinafter referred to as an up-switching element J) and a second switching element Qd (hereinafter referred to as a down-switching element);
and the first diode D□ for ringing prevention.
112 providing a conductive path between the output terminal 2 of a part formed by a fist-type cathode floor of the type and a point P of a part formed by a resistor RQ and a down-switching cable Qa, forming a type of inverter 112 A circuit is constructed by *M*L with a diode D, and an input voltage Vi having a peak value of, for example, about 5V is added to the input terminal 1 of the cutting path, and from output terminal 2, an input voltage Vi having a peak value of, for example, about 100V is applied. The output pulse voltage Vo is taken out.

By the way, circuit systems using bipolar transistors or insulated gate field effect transistors as shown in FIG. 2(a) are generally considered as switching elements. However, in this circuit of FIG. 2(a) and the circuit of FIG. 1, 3 is a DC power supply voltage of about 100 V (8), and 4 is a gate bias voltage V of about 5 V.

, respectively, and what is shown as co is the equivalent capacitance of the display element.

In the circuit of FIG. 2(a), the input pulse voltage V as shown in FIG. 2(b) with a peak value of 5V is applied to the input terminal 1.
When i is applied, Q- turns on, so the output pulse voltage V
O falls to the ground level shown as A. In this case, the current flowing through the resistor R0 and Mo5T-Qd as shown by the arrow C is a reactive current that is unrelated to the current supplied to the load flowing through the arrow port, so it is desirable to make it as small as possible. Therefore, it is conceivable to increase the resistance Ra. However, Mo5T-Qd (hereinafter referred to as down MO3
) is Mo3T' Qu (hereinafter referred to as up M
For example, if it is a high power type that can withstand a current of about 0.5V, the MO5T-
For example, the output capacitance between the source and drain of Qd *C+ is 100
It has a large value of ~200PF. If the resistor R6 has a value of, for example, IOKΩ, then RQ'
Since the time constant determined by Cd is approximately 1 to 2 .mu.sec, the output pulse voltage V at the time shown as tr in FIG. 2(b).

The rise of 9 becomes very dull and no longer sharp.

Furthermore, if bipolar transistors are used as up and down switching elements, the rise of the output pulse voltage Vo will be better because the output capacitance of the bipolar transistor is small, as will be explained later, but as is well known, bipolar transistors have an accumulation effect of minority + yaria. Therefore, the above-mentioned nine-hole extraction has the disadvantage that it generates a current.

The present invention has been made in view of these points, and includes an up-switching element connected between a power supply and an output terminal, a diode connected between the output terminal of the up-switching element and ground, and a diode connected between the output terminal and the up-switching element. A pulse amplification circuit having a diode providing a conductive path between the up-switching element and the input terminal, and a down-switching element connected to the input terminal of the up-switching element to ground, wherein the up-switching element is a field effect transistor; This invention provides a Paris amplifier circuit characterized by using a bipolar transistor as a down switching element, and will be described in detail with reference to the drawings in FIGS. 3(a) and 3(b).

FIG. 3(a) is a circuit diagram showing an embodiment of the pulse amplifying circuit according to the present invention, in which parts equivalent to the 211th (-) are given the same symbols.

The main feature of No. 31!1(a) is the upsweep.

The switching element is made of Mo5T, which does not have a bias accumulation effect, and the down-switching element is a bipolar transistor with a small output capacitance.

Therefore, the polarity of each voltage -2Va applied to terminals 3 and 4 must be positive. However, the above-mentioned up MO8
A p-channel type is used as T'Qu, and a pnp type is used as a down switching element, that is, a down transistor Q-.
II can also be used, in which case each of the above voltages %
, the polarity of Vc may be negative.

Below, according to the circuit diagram of Fig. 3(a), the up MOs'
An example in which an n-channel n/type is used as rQu and npnll is used as the down transistor will be explained.

First, in the timing chart drawn with time t as the horizontal axis, that is, in FIG. 3(b), at time tl, a high level input terminal V is applied to the input terminal 1 of the circuit in FIG. 113(4). Suppose that Thus, Figure 13 (in ω)
The base voltage of the down transistor false rises to about α7v, for example, and as a result, the down transistor turns on. Then, the potential at point p, and therefore the gate voltage of up MO5T-QIl, is grounded to the ground level.

By the way, this up-MO5T-Qu is an enhancement type, and its threshold voltage is, for example, +3V, so the MO5T- is turned off, and as a result, the voltage Vo at the output terminal 2 becomes the voltage Vo of No. 311(b). It is at a low level as seen at time t1.

Here, considering the 311th (Mt when d), the above input voltage V
When i falls, the base voltage of down transistor Q4 becomes Grantley e
:/&/, resulting in the transistor being turned off.

A current for charging the corephthal emitter output capacitance CC of the above-mentioned transistor flows from this power supply terminal 3 through the resistor as shown by arrow C. Voltage i.e. up M
The gate voltage of O3T-Qu increases.

For this reason, MMO8T-Q is in the ON state at 1s ts9, and the current yielded from the power supply terminal 3 through the MO5T-Q flows into the load capacitance co of the display device as shown by the arrow. to charge the capacitor Co.

MO8T-Q shown in FIG. 2 (51) above
u.

Even if it can withstand a large current of about 0.5A like Qa, the corephtal-emitter output capacitance Cc of a bipolar transistor is generally small, for example, about 15PF, and the output capacitance C- of MO5T is small. It is about ~-.

For this reason, the above time 1. Since the rise time constant of the output cover and the sumi pressure is shortened to about 1 to -, the waveform of the output pulse voltage Vo can be made sharp as shown in Fig. 1113 (b). .

In the pulse amplification circuit according to the present invention described above, a sharp output pulse voltage waveform can be obtained as described above, so that great practical effects can be expected.

[Brief explanation of the drawing]

Figure 1 shows a conventional circuit used to drive a display device, and Figure 2 (- indicates MO5T as a switching element.
Figure 3 (-) is a pulse amplification circuit according to the present invention, Figure 3 (b) is a diagram showing the human output pulse waveform of the circuit example, and Figure 3 (b) is a diagram showing the human output pulse waveform of the circuit example. It is a timing chart showing the operation of 1: input terminal, 2: output terminal, 3, 4: voltage supply terminal,
No.-91-Co' Capacitive load of display element, Cc: Corephtal-emitter capacitance of bipolar transistor, D
,,D,: diode, Qu '' up switching element, Qa: down switching element.

Claims (1)

[Claims] an up-switching element connected between the power supply and the output terminal; a diode connected between the output terminal of the aI7 switching element and ground; and a diode providing a conductive path between the output terminal and the input terminal of the up-switching element. A pulse amplification path having a biasing resistor between the power supply and the input terminal of the up-switching cable and a down-switching element connected between the input terminal of the up-switching cable and ground; A pulse amplification path characterized in that a field effect transistor is used as a switching element and a bipolar transistor is used as a down switching element.