# The method of limiting the output current

(57) Abstract:

The invention relates to electrical engineering and can be used in the integral analog devices. Speed limits the output current, as well as expansion of the range of regulation of the shape of the transfer characteristic is achieved in that in the method of limiting the output current is to use the dependence of the amount of alternating currents flowing in the two nonlinear electrical circuits containing a counter included p-n junction, the input voltage applied to these circuits perform linear combination of the specified sum of currents of the alternating current flowing in the third nonlinear electric circuit under the influence of the input voltage. 2 Il. The invention relates to electrical engineering and can be used in the integral analog devices.A known method of limiting the output current, which consists in the fact that the input voltage is applied to a nonlinear electrical circuit containing a pair of counter enabled p-n junctions, and arising in the circuit of an alternating electric current is used as the output current. (S Soclof. Analog integrated circuits. M Myristicae. M Energy, 1973. S. 15).Also known a method of limiting the output current (the United Kingdom Patent N 2217541, CL H 03 F 1/32, 3/45), namely, that the input voltage fed to the inputs of two composite differential amplifier, and the output current is obtained by summing the output currents of these amplifiers.The disadvantage of these methods current limitation is the slow performance while reducing the level of the output current, as well as the inability to control the shape of the transfer characteristic.The closest to the technical nature of the claimed method is a method of limiting output current [1] consists in the fact that the input voltage is served on the first nonlinear electrical circuit formed by the first and the second counter is enabled by AC pramosone p-n-transitions, and the second nonlinear electrical circuit formed by the third and fourth counter included AC pramosone p-n-transitions.The disadvantage of this method is the low performance at low levels, limiting the output current, as well as a small range control form transmitting characteristics.The purpose of sirovanija shape of the transfer characteristic.The purpose of the invention is achieved by the fact that the input voltage is served on the first nonlinear electrical circuit formed by the first and the second counter is enabled by AC pramosone p-n transitions, the second nonlinear electrical circuit formed by the third and fourth counter included AC pramosone p-n-transitions, and the third non-linear electrical circuit formed by the fifth and sixth counter included AC pramosone p-n-transitions, and the output current is formed by the formula (i_{o}=a

_{1}(i

_{1}+i

_{2})+a

_{2}i

_{3}where i

_{1}, i

_{2}, i

_{3}the currents flowing respectively in first, second and third nonlinear electrical circuits under the influence of the input voltage; a

_{1}and a

_{2}constants.New the essential feature of the proposed method is that the nonlinearity sold with it, the transfer characteristic is a function of the different nonlinearities three nonlinear electrical circuits, and the parameters of nonlinearity of each of these circuits can be set independently (by the proper choice of values flowing through the p-n junction displacement currents).harakteristiki, in particular, considerable non-linearity characteristics at very small values of the input voltage, when the nonlinearity of each individual nonlinear circuit is even slightly. The latter circumstance allows to effectively limit the output current at levels significantly lower values of current bias p-n junctions. As in this case, p-n-transitions remain in small-signal mode in the entire range of variation of the output current, provides better performance compared with the prototype and analogues, in which the output current limiting is achieved by operation of the respective p-n junctions in a substantially non-linear mode.In Fig. 1 shows the electric diagram of the device, which can be implemented by the proposed method.The device comprises a first 1 and second 2 transistors, basic-emitter p-n junction which, together with the capacity of 3 form a first non-linear circuit, the third 4 fourth 5 transistors, basic-emitter p-n junction which, together with the capacity of 6 form the second non-linear circuit, the fifth 7 and 8 sixth transistors, basic-emitter p-n junction which, together with the capacity of 9 or input device, base 2 second, fourth, 5 and 8 sixth transistors are of a second input device, the collectors of the transistors connected to the corresponding inputs of the Converter 10 which forms the output current according to the formula i

_{o}=a

_{1}(i

_{1}+i

_{2})+a

_{2}i

_{3}the outputs of the Converter 10 are the outputs of the device and connected to the load circuit 11, the bias currents of p-n junctions defined by the current generators 12 17.In Fig. 2 depicts the transfer function implemented by the proposed method.The proposed method is carried out using a shown in Fig.1 device as follows.Originally electrodes of the transistors and the power bus serves a voltage of this magnitude to bring all the transistors in the active mode. After that, between the first and second inputs of the device applied input voltage.In this case, assuming that the input frequency is much less than the cutoff frequency of the transmission factor of the transistors used in the current in the circuit with a common base, the base currents and the reverse currents of p-n junctions of the transistors are negligible in comparison with their collector currents, the resistance of the containers 3, 6 and 9 pre is transitory identical, the output current of the current generator 12 is equal to an output current of the current generator 16, the output current of the current generator 13 is equal to an output current of the current generator 17, we can write the following expression relating the magnitude of the input voltage values occurring in nonlinear electrical circuits, currents

< / BR>

where i

_{1}, i

_{2}, i

_{3}the alternating currents flowing in the first, second and third nonlinear electrical circuits, respectively;

I

_{01}the value of the output currents of the current generators 12 and 16;

I

_{02}the value of the output currents of the generators 13 and 17;

I

_{03}the value of the output currents of the current generators 14 and 15;

_{t}temperature potential.Ratio (1) allow to Express the values of the currents i

_{1}+i

_{2}and i

_{3}through U

_{I}< / BR>

< / BR>

Therefore, the output current is equal to

< / BR>

An equation was implemented using the proposed method transfer characteristics may be conveniently presented in normalized form

< / BR>

From expressions (2)-(4) it follows that the shape of the transfer characteristic is determined by the coefficients k and m, i.e. the values of the constants a

_{1}and a

_{2}and the ratio of the displacement currents of p-n junctions.Changing these settings aredata characteristic y(x) when m=2, k, as well as the corresponding dependence of y

_{1}(x) and y

_{2}(x). The dependence y(x) shown by the solid line, y

_{1}(x) and y

_{2}(x)- dashed lines.If the ratio of m different from unity (i.e., the currents I

_{01}and I

_{02}different), and the coefficient k is negative (i.e. the constants a

_{1}and a

_{2}have opposite signs), in order to limit the i

_{o}the value of U

_{I}may be significantly less than the values U

_{I}at which there is a current limitation i

_{1}+i

_{2}and i

_{3}(see Fig. 2). This implies that the proposed method provides the ability to effectively limit the output current when the p-n junctions in small-signal mode corresponding to the minimum inertia.Thus, the proposed method differs from the prototype and analogues advanced control range form transfer characteristics and performance limitations of the output current. The method of limiting the output current, which consists in the fact that the input voltage is served on the first nonlinear electrical circuit formed by the first and the second counter is enabled by AC pramosone p - n perekhodnomu current pramosone p - n transitions, characterized in that the input voltage can also be enjoyed on the third nonlinear electrical circuit formed by the fifth and sixth counter included AC pramosone p n transitions, and output current is formed by the formula

i

_{o}a

_{1}(i

_{1}+ i

_{2}) + a

_{2}i

_{3},

where i

_{1}, i

_{2}, i

_{3}the currents flowing respectively in first, second and third nonlinear electrical circuits under the influence of the input voltage;

a

_{1}and a

_{2}constants.

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