SU843167A1 - Amplitude limiter - Google Patents

Description

(54) AMPLITUDE LIMITER

The invention relates to radio engineering and can be used in precision radio engineering devices and control systems.

Known amplitude limiter containing serially connected operational amplifier and. parallel limiter 1-.

However, in the known amplitude limiter the coefficient of transmission in the region of the linear characteristic depends on the magnitude of the load.

The purpose of the invention is improving the accuracy of signal transmission in the linear region.

This goal is achieved in that in the amplitude limiter containing serially connected operational amplifier and parallel limiter, a voltage divider is connected between the output of the parallel limiter and the common 4ain, for example, in the form of a potentiometer, whose output is connected to the inverting input of the operational amplifier and device output.

Figure 1 shows the structural electrical scheme of the proposed

devices; on;; 2 is a static characteristic of the device.

The T-limiter contains an operational amplifier (OA) 1, a parallel limiter 2 with a current-carrying resistor 3, a voltage divider made in the form of a potentiometer 4.

The device works as follows.

0 way.

The input signal Ugx is fed to the non-inverting input + OU 1. The output signal of the OA 1 (U) is supplied

5 to the input of the parallel limiter 2. If and Uorp, where Uotp is the Level of restriction of the parallel limiter 2, then the output signal of the device is

0

Jijl

()

you v

1 + kp

where is the feedback factor.

25

 / fa .-)

Р- .s (- 7Г,

thirty

 Resistor 3 Kf- Resistance potentiometer 4 ,. Rjj is the load resistance; cc - transfer ratio (division)

potentiometer 4.

If U is 7 Uorp, then the output signal of the device has a constant value, determined by the following expression:

O (-RH / (/ n)

 EXIT max "sCi-)

The adjustment of the limiting level is made with the help of a potential pL. -.

The gain of 1 oCh7Gk5 / device in the region of the linear characteristic (Fig.2) depends on the naparJjetpoB scheme and is always less than 1. However, due to the high gain. For op amp 1, the change in the p value over a wide range affects the coefficient slightly.

For example, at IO2.10 (for operational amplifiers of the 153 series) the change is. 0.01% occurs when the value of p is about 200 times.

If a high speed amplitude limiter and a limiting accuracy are not required, instead of parallel limiter 2, you can use the natural limitation of the operational amplifier.

For proof of the effect achieved, consider an example implementation of an amplitude limiter, in which you naturally use the limiting amplifier.

Let, for example, when determining the value of the voltage

operational amplifier 1 10 and the required range of limiting level from 0.1 to 58.

Under the indicated requirements, the value - | 3 should vary, respectively, from 0.01 to 0.5, which entails a change in the coefficient within 0.995 KQO, 999.

Such a change in the K coefficient is extremely small and. valid for a wide range of devices.

In the known limiting devices without reversing the phase of the input signal with one regulating element, a change in the level of limitation, for example, doubles the K coefficient. by about the same amount that is already unacceptable for many electronic devices.

Claims (1)

Invention Formula . Amplitude limiter, a series-connected operational amplifier and a parallel limiter, characterized in that, in order to increase the accuracy of signal transmission in a linear region, a voltage divider is connected between the output of the parallel limiter and the common bus, for example, in the form of a potentiometer, whose tap with the inverting input of the operational amplifier and is the output of the device. one Sources of information taken into account during the examination 1. Design and use of operational amplifiers. Ed. Grema, M., Iir% 1974, p. 425, fig. 10.21, (prototype). (Je ShH Ml Maty i /, 2