JPS6081909A - Voltage limiter circuit - Google Patents

Abstract

PURPOSE:To prevent a limiter voltage from varying according to variation in the drop voltage across a diode with temperature by connecting two diodes in series in opposite-polarity relation and connecting their connection point to a power source through a resistance. CONSTITUTION:A transistor (TR) 4 is inserted as the voltage limiter circuit of an operational amplifier 1 in parallel to a feedback impedance element 2. A diode 5 inhibits a current from flowing reversely to the output of an amplifier 2 through the base electrode of the TR4. Another diode 12 is connected to the diode 5 in series in opposite-polarity relation, a voltage is applied to their connection point through the resistance 13, and the reference value of the limiter potential to be set is applied to the diode 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heavy pressure IJ emitter circuit for an itch amplifier.

Conventionally, this sleeve is 1! ! As a circuit, as shown in Figure 1, in Figure 1, we have (1) a gain term width amplifier, (2) a feedback impedance, and (3) a human input and a feedback impedance. ,! 41H limiter PNP transistor, (5) reverse current blocking diode, (6) bending current limiting resistor, +7) I-t limiter voltage setting once a month volume.

Next, the operation will be explained. 1. Set the limiter voltage to an arbitrary value using the limiter voltage setting volume (7).

Next, if the input (slic'm pressure is 711), an amplified signal is obtained at the output (91) by the transfer function of the input resistor (3) and feedback resistor (2).The input-output relationship at that time is This is shown in Figure 2. When the output i91K obtained signal θ level is below the level (11) set by the limiter voltage setting volume (7), the proportional amplification (10) operates and the output +9 (' When the rg level limiter voltage reaches Bell IIIVC, PNPN
Since the emitter level is higher than the base potential of the upper transistor (4), the limiter PNP transistor (4) is
A current flows from the emitter of the transistor 14) and the transistor 14) is suppressed to the limiter pressure level (11). Output (9) is on diode (6)! This is designed to prevent breakdown due to the voltage applied to the base and emitter of the transistor (41) when the voltage is applied to the base and emitter of the transistor (41).

Since the conventional platform ivy circuit is configured in the above five ways, as shown in Figure 42, the temperature variation of the drop quasi-pressure of the five diodes 15) △VK limiter voltage level 111)
The disadvantage is that fC changes with temperature.

This light source was designed to eliminate the drawbacks of the conventional one, such as the diode and reverse polarity.
By connecting the if column and connecting it to the '@ source through the open resistor, the limiter voltage level changes to t due to the change in the drop voltage of the diode. A complete limiter circuit capable of stopping 1X14 is provided.

An embodiment of the present invention will be described below with reference to the drawings. M3
In the figure, ++2' temperature change guarantee diode, +
13) RI specific output 9) Resistance for flowing the rippling current, one end breaks to the source.

Next, the operation will be explained. When the signal at the input 18) is amplified and the old value obtained at the output (91) exceeds the limiter voltage level, current flows from the emitter of the limiter PNP transistor I4+ to the negative power supply through the diode (51 and resistor (131'i). flows in and the output (91 cannot be suppressed to the limiter voltage. At that time, the level set by the limiter voltage setting volume +71 VC, point θ4)
In the light diode (121 drop force voltage is lower level VC, but the output i91) 11 voltage V
Since the level VC is higher by the drop pressure of the diode (51), the level set by adjusting the limiter voltage setting volume +71 K becomes equal to the level of the output (9), and the error due to temperature changes. It doesn't work anymore.

Also, as shown in @4 diagram, limiter river transistor > NP
N Sugi transistor (151Kt, reverse polarity diode (161, (Iγi), between which resistor (1) connected to positive power supply, limiter voltage setting volume Q
By connecting 91"k between the negative and common terminals, it is possible to apply the limit to the negative value of the thorn reversibility shown in FIG. 3.

In the above, all 41 transistors were used, but semiconductor elements with control poles other than transistors and vacuum tubes can also be used.
month is possible. Further, a diode or other rectifying element may be used.

As mentioned above, in this case, two diodes are connected in series in reverse order, and the voltage Vc is connected through the point resistor, so that the error due to temperature change is reduced.
It has the effect of making you look up to something with great precision.

[Brief explanation of the drawing]

Figure 1 shows a conventional amplifier circuit with a limiter circuit, Figure 2 shows the input/output relationship of the circuit, Figure 3 shows the 41%μ
This is an embodiment of the present invention. ;1:...jW4'1iitW, +21...Feedback impedance, (3)...Input impedance, (41
...PNPN upper type resistor, +51° (12., Q
fil, t+71...diode, H, t+3+
, f+a+...resistance, (7). [+ 9)...Volume, (151...NPN transistor: tz b, same as 14- sign in the figure, or reduce the corresponding part 0 Agent Masuo Oiwa

Claims (1)

[Claims] Arithmetic 111 Heavy pressure limiter circuit of width amplifier - commonly referred to as a transistor inserted in parallel with the feedback impedance, the rd I
a first diode that completely blocks current flowing in the opposite direction to the output of the transistor according to the base Mkm of the transistor; and a second diode whose anode and cathode are connected in series La in reverse to the first diode; Apply a voltage across the resistor to the connection point of two diodes, and apply the reference value of the limiter potential to be set to the second diode? Features a voltage limiter circuit.