SWITCHING CONFIGURATION FOR A MEANS OF A STEUERGROESSE CONTROLLABLE ONE AN ELECTRONIC RESISTANCE

The invention refers to a switching configuration for an electronic resistance, which is controllable by means of a Steuergröße. Controllable electronic of resistances are particularly needed as control members in automatic control loops from amplifiers to the automatic automatic constant of a certain signal level. With many S of the applications, for example in automatic control loops of carrier frequency amplifiers, thereby the demand exists after a high controlling border as well as a high distortion attenuation of these control members, in order to be able to transfer temporarily arising voltage peaks of the signal distortion-free. In other applications, for example in receipt circuits of data transmission devices (modems), additionally to the requirements mentioned a fast a rockers of the Regelkreiees is demanded. By means of diodes, whose operating point is changed, it is possible to develop switching configurations for controllable electronic of resistances. In most applications however the controlling border is too low with these scolded ungsanordnungen because of the nonlinear diode characteristics. This is valid also for an arrangement, with which the controllable electronic resistance is formed by the emitter collector distance of a transistor. A higher controlling border lets itself reach with an arrangement formed from a foreignheated pyroelectric conductor. This arrangement is however because of the high thermal time constant of the pyroelectric conductor and the large Einschwingzeit of the rule circuit in many cases, due to it, useless. The invention is the basis the task to create a switching configuration for an electronic resistance controllable by means of a Steuergröße its Elirrdämpfung and controlling border is as large as possible in relation to the appropriate values of well-known semiconductor arrangements and one about just as low control time constant exhibits as these semiconductor arrangements. This task solved according to invention by from a first resistance and a voltage divider existing from the Steuergröße directly angesteuertea second resistance, with which the interconnect point of the two resistances is connected with the entrance of an amplifier, whereby the exit of this amplifier is connected by a third resistance with an end of the voltage divider and the two ends of this voltage divider form the clamps of the electronic resistance. The invention is continued to describe now under Bezuguahme on examples, which are represented in the designs. In the designs Fig.1 shows the circuit diagram of the switching configuration in accordance with the invention, Fig.2 an example with the switching configuration according to invention as part of an electric circuit, Fig.3 the switching configuration of a possible remark example of the invention, Fig.4 the switching configuration of a further remark example of the invention. In Fig.1 the voltage divider becomes --ST-- by the series connection of the first resistance --G 1-- with the second resistance --R2-- formed, which by means of the Steuergröße --S-- is controllable. The interconnect point of resistance --G 1-- and resistance --R2-- is with the entrance of the amplifier --V-- connected. The exit of the amplifier --V-- is over the resistance --R3-- with the free end of the resistance --R2-- connected. Between the two ends of the voltage divider --ST-- the desired electronic resistance steps --RS1-- up. With the following explanation of the invention are to be made the easier understanding the simplifications that by the voltage divider --ST-- flowing river I2 is small related to by the electronic resistance --RS1-- flowing river I1, with which this river I1 approximately equal by the resistance --R3-- flowing river Iö it is and that the internal resistance of the amplifier --V-- is negligibly small, related to the value of the resistance --R3--. Is because of the electronic resistance --RS1-- a sinusoidal alternating voltage U1 on, then steps at the exit of the amplifier --V-- then an alternating voltage UI' = ü. U1 up, whereby itself the factor ü from the divisor relationship of the voltage divider --ST-- as well as the Eingangswide} - stood and for the reinforcement of the amplifier --V-- results in. At the clamps of the resistance --R3-- an alternating voltage lies close, which results from the difference of the alternating voltages U1 and Ut': U1 - ü. U1 - U1. [1-ü). By the resistance --R3-- flowing river I3 lets sic, h from there from the relationship of this differential voltage to the value of the resistance --R3-- determine: I3 = U1 • (1-ü) ~ I1 B8 Nr.358100 (I) from this relationship the value of the electronic resistance is calculated --R-S! -- to u1 E8 BSI = ~ I1 1-ü ₜ 2) from this comes out that the electronic resistance --BS1-- by changing the factor fi to be steered can. The factor ü again can by changing the Steuergröße --S-- are steered. A favourable arrangement consists of that as controllable second resistance --B2-- the emitter collector distance of a transistor serves, whereby the resistance of this distance is steered by means of the base voltage. Because of this emitter collector distance only one part is at the electronic resistance --BS1-- dominant tension U1 on. The switching configuration in accordance with the invention has from there the advantage that the values for controlling border and distortion attenuation lie substantially more highly than in the initially mentioned cases, with which the tension U1 rests directly against the emitter collector distance of a transistor and/or cathode anode distance of a diode. Is the electronic resistance --BS1--, as in Fig.2 shown, in an electric circuit switching on, for example into the inverse feedback circle of an amplifier, then a large voltage drop arises at it with large resistance values. From for the electronic resistance --RS1-- indicated relationship (2) it comes out that at large positive values of --RS1-- the factor ü a value somewhat smaller than 1 exhibits. This means that itself then as the second resistance --R2-- used transistor in the niederohmischen condition finds. This behavior is a further advantage in relation to the initially mentioned arrangements, with which with a high impedance condition also the transistor concerned and/or the diode is in the high impedance and thus particularly überstenerungsempfindlichen condition. In the remark example represented in Fig.3 is the amplifier --V-- with a inte2S Opsrationsverstärker grierten developed, whereby the Spannungsverstärkung of the amplifier exhibits the value v = +I. As controllable second resistance --R2-- the field-effect transistor serves --Tl--, its refining electrode over the Ohm's resistance --R4-- with as Steuergröße --S-- is connected for serving source of control voltage US. Parallel to the SOURCE drain distance of the transistor --Tl-- is the Ohm's voltage divider --ST' switched, whereby between its pick-up and the refining electrode of the transistor --Tl-- the condenser --CI-- is arranged. This condenser --CI-- serves in connection with the voltage divider --ST' and the resistance --R4-- to the inverse feedback of the transistor --Tl-- and thus for the increase of the Hlirrdämpfung. By change of the control voltage US the electronic resistance becomes --BSI-- steered. With the resistance of the Spannungstei [ers --ST' the border of the Begelbereiches of the electronic resistance can --RSI-- are affected. ] [no voltage divider st --ST' necessarily, then can for the influence of the Begelbereiches in place of the voltage divider --ST' also only one resistance to be used. As resistance --R-S-- a Ohm's resistance is used. According to the relationship C2) are then the values of the electronic resistance --RS1-- really. In another arrangement of the invention is the resistance --By-- complex. I receives on then for the electronic resistance --RS1-- likewise a complex resistance. How from the relationship (2), is this resistance comes out --RS1-- only dependent on the value of the real factor ü. The complex resistance --BSI-- has from there the same phase angle as the complex resistance --By--. Uses one for example as resistance --By-- an inductance, then steps as electronic resistance --RS1-- an appropriate changeable inductance up. With this execution form of the invention for example the Besonanzfrequenz of a LC-resonant circuit within a wide range lets itself steer. In Fig.4 a further remark example of the invention is represented. The amplifier --V-- becomes with the NPN transistor --T2-- realized, its emitter forms the amplifier exit and its basis the amplifier entrance. The interconnect point of the resistance implemented as Ohm's resistance --R3-- with the voltage divider --ST' and the Souros drain distance of the transistor --Tl-- is with a pole a Gleiohspannungsquelle UB (tension OV} connected and forms again the one clamp of the electronic resistance --RSI--. The resistance --RI-- becomes by the series connection of the two Ohm's resistances --RI.I and RI.2-- formed, whereby the latter the condenser --C3-- is joined in parallel. The interconnect point of collector of the transistor --T2--, Condenser --C3--, Resistance --BI.2-- and an end of the resistance --R5-- the other clamp of the electronic resistance forms --RS1--. The other end of I0 of the resistance --R-S-- is connected with the other pole of the Gleichspannungsquelle UB positive in this case. The series connection of the SOURCE drain distance of the transistor --Tl-- with the condenser --C2-- lies between tension OV and the interconnect point of voltage dividers --ST', resistance --Bi.l-- as well as the basis of the Transisters --T2--. The Ohm's resistance --B3-- furthermore serves in connection with the resistances --RI.I, BI.2 and B5-- as well as the voltage divider --ST' for adjustment the operating point of the transistor --T2--. The condenser --C3-- closes the resistance --BI, 2-- alternating current-moderately briefly. By an appropriate choice of the relationship of the resistances --RI.I and R1.2-- is an additional adjustment possibility for the factor ü and/or for the range of control of the electronic resistance --RS1-- given. In place of the Ohm's resistance --R3-- also a complex resistance can be used. In this in case must then because of the operating point of the transistor --T2-- to a certain d.c. resistance to be paid attention. Since individual transistors exhibit a higher critical frequency opposite operation amplifiers, the remark example is suitable after Fig.4 particularly for high frequencies. Generally know case after Fig.l the resistance --BI-- and the controllable second resistance --R2-- exchanges also against each other arranged its. As controllable second resistance--R2-- for example also a Phototransistor or a Feldplatte can serve. The Steuergröße --S-- to the controlling of the electronic resistance--RSI-- is then a source of light and/or a magnetic field. Becomes the input impedance of the amplifier --V-- measure accordingly low, then can on the resistance --El-- are done without. PATENT TO THE P B ÜCHE; !. Switching configuration for controllable an electronic by means of a Steuergröße resistance, characterized by one from a first resistance (El) and one of the Steuergröße (s) directly steered second resistance (R2) existing voltage divider (ST), with which the interconnect point of the two resistances (BI, B2) with the entrance of an amplifier (V) is connected, whereby the exit of this amplifier is connected (V) by a third resistance (R3) with an end of the voltage divider (ST) and the two ends of this voltage divider (ST) the clamps of of the electronic resistance (RSl) form. 2. Switching configuration according to requirement I, thereby characterized that the controllable second resistance (R2) by the emitter collector distance of a transistor (T!) one forms, whose is connected to base electrode ko by a fourth resistance (R4) with a source of control voltage (US). 3. Switching configuration according to requirement 1, by characterized that the controllable second resistance (R2) is formed by the SOURCE drain Streeke of a field-effect transistor (tl), whose gate electrode is connected by a fourth resistance (R4) with a source of control voltage (US). 4. Switching configuration according to requirement 2 or 3, by characterized that the emitter collector distance and/or the SOURCE drain distance of the transistor (tl) a further voltage divider (ST') is joined in parallel, between its pick-up and Basisbzw. Gate electrode a condenser (c1) is attached.