Controller for electronically controlled resistors

Abstract

A controller for an electronically controlled resistor includes a controllable current generator that outputs an output current, an amplifier that receives an input voltage proportional to the output current and outputs an amplified input voltage to a first input of a summer, a voltage divider connected between the high potential and low potential terminals of the electronically controlled resistor, and a buffer stage that receives the output of an external sense resistor and outputs a buffered voltage to the controllable current generator and to a second input of the summer to control the output current, the summer outputs a summed voltage, and an operational amplifier receives the divided voltage and the summed voltage and outputs a control voltage to an external active element, the active element and the sense resistor being connected in series between the high potential and low potential terminals of the electronically controlled resistor.

Description

[Technical Field]

[0001] This invention relates to the fields of electrical and electronic engineering, and more particularly to measuring instruments, power electronics, radio engineering and communications, and consumer electronics. More specifically, this invention relates to controlling changes in the resistance of a circuit portion by electronic means. [Background technology]

[0002] Changing the resistance of a circuit over a wide range using electronic means is a high priority in many electronic applications. Solving this problem will open up new possibilities for creating automated electrical devices, wireless devices, and other applications, including the Internet of Things (IoT).

[0003] A controller for an electronically controlled resistor (ECR) generates a control voltage, which changes the resistance of the active element of the ECR over a wide range depending on the amount of input action.

[0004] The aforementioned ECR generally includes an active element, a measuring (detecting) resistor, and an ECR controller. The input action relates to changing the resistance of a variable control resistor, such as a mechanical potentiometer, photoresistor, thermistor, or digital potentiometer, which is not part of the ECR.

[0005] Numerous solutions are known in this technical field. For example, Japanese Patents RU2666786, RU2661348, RU2658681, US10447167, I670920(TW), I674742(TW), and KR10-2054359 disclose controllers for active elements of ECRs, which feature the following characteristics - The first terminal of the controller for connecting the circuit to the control voltage source, - The second terminal of the controller is used to connect the circuit to the low-potential terminal of the ECR, - The third terminal of the controller, which acts as an output and is used to connect the circuit to the control terminal input of the active element, which is part of the ECR. It has (see Figure 1 in these publications showing conventional controllers).

[0006] A conventional controller further includes an operational amplifier, a reference resistor, a feedback resistor, and a constant voltage source, wherein the non-inverting input of the operational amplifier is connected to the first terminal of the reference resistor, and the second terminal of the reference resistor is connected to the first terminal of the controller. The non-inverting input of the operational amplifier is also connected to the first terminal of the feedback resistor, and the second terminal of the feedback resistor is connected to the output of the operational amplifier, which is then connected to the third terminal of the controller. The inverting input of the operational amplifier is connected to the positive terminal of the constant voltage source.

[0007] This conventional solution is, - In particular, when there are destabilizing factors such as ambient temperature, the precision of resistance control in the circuit section is insufficient. - Lack of the ability to use variable resistors (photoresistors, thermistors, digital potentiometers, etc.) to control the resistance of the circuit components. This has the drawback.

[0008] Another conventional solution is disclosed in publication SU1807554, dated April 7, 1993. A conventional controller for controlling the resistance of the circuit section (see Figures 2 and 3 of the above publication) - The first terminal of the controller is used to connect the circuit to the high-potential terminal of the ECR, - The second terminal of the controller, which acts as an output and is used to connect the circuit to the first terminal of the detection resistor, which is part of the ECR, - The third terminal of the controller is used to connect the circuit to the control action source as a variable analog voltage, - The fourth terminal of the controller is used to connect the circuit to the low-potential terminal of the ECR. Includes.

[0009] The conventional solution is, - Control action conversion circuit, - Operational amplifier and, - Feedback resistor, - Limiting resistor, - Constant voltage source and It further includes, The non-inverting input of the operational amplifier is connected to the first terminal of the limiting resistor, and the second terminal of the limiting resistor is connected to the fourth terminal of the controller. The inverting input of the operational amplifier is connected to the output of the control action conversion circuit and to the first terminal of the feedback resistor, and the second terminal of the feedback resistor is connected to the output of the operational amplifier and to the second terminal of the controller. The first input of the control action conversion circuit is connected to the first terminal of the controller, its second input is connected to the third terminal of the controller, and its third input is connected to the positive terminal of the constant voltage source.

[0010] The output of the operational amplifier is connected to the second terminal of the controller.

[0011] This conventional solution is, - Inability to control the active elements of the ECR. - Lack of the ability to use variable resistors (photoresistors, thermistors, digital potentiometers, etc.) for control. - There is an inverse relationship between the resistance of the ECR and the control action represented by the changing analog voltage. - Lack of the ability to achieve the often required ECR (Electronic Cross Resistance) of sufficiently low resistance. This has the drawback.

[0012] A final disadvantage results from the fact that in conventional solutions, the current flowing through a detection resistor passes along a path through a series-connected limiting resistor and reference resistor, and terminates at a common line. Therefore, there is a practical relationship between the resistance of an ECR and the resistances of the limiting resistor and the reference resistor. This relationship can only be ignored when the resistance of the detection resistor is many times higher than the combined resistance of the limiting resistor and the reference resistor, and this causes the above-mentioned disadvantage.

[0013] Another conventional controller for resistance of circuit portions is disclosed in U.S. Patent No. 4,833,472, dated May 23, 1989.

[0014] This conventional solution comprises: - a first terminal of the controller, used for connecting a circuit to a high potential terminal of an ECR; - a second terminal of the controller, used for connecting a circuit to a first terminal of a detection resistor that is part of an ECR; - a third terminal (group of terminals) of the controller, used for connecting a circuit to a control digital code source; - a fourth terminal of the controller, used for connecting a circuit to a low potential terminal of an ECR; - a fifth terminal of the controller, which functions as an output and is used for connecting a circuit to a control terminal input of an active element that is part of an ECR (see FIG. 1 of the above publication).

[0015] The conventional controller further comprises an operational amplifier, a multiplier, and a digital-to-analog converter, a non-inverting input of the operational amplifier is connected to the first terminal of the controller, an inverting input of the operational amplifier is connected to an output of the digital-to-analog converter, an input of the digital-to-analog converter is connected to an output of the multiplier, and an output of the operational amplifier is connected to the fifth terminal of the controller, The controller's third terminal (group of terminals) is connected to the multiplier's first input (group of inputs), and the input of the second multiplier is connected to the controller's second terminal.

[0016] The main drawback of this conventional solution is that it does not allow the use of variable resistors (such as photoresistors, thermistors, or digital potentiometers) for control.

[0017] Another conventional controller for the resistance in the circuit section is disclosed in JPS5111404, dated October 7, 1976.

[0018] This conventional solution is, - The first terminal of the controller is used to connect the circuit to the high-potential terminal of the ECR, - The second terminal of the controller is used to connect the circuit to the first terminal of the detection resistor, which is part of the ECR. - The third terminal (group of terminals) of the controller, used to connect the circuit to the control digital code source, - The fourth terminal of the controller is used to connect the circuit to the second terminal of the control digital code source, - The fifth terminal of the controller is used to connect the circuit to the low-potential terminal of the ECR, - The controller's sixth terminal, which acts as an output and is used to connect the circuit to the control terminal of the active element, which is part of the ECR. This includes (see Figure 1 in the above publication).

[0019] Conventional controllers further include an output operational amplifier and an intermediate operational amplifier, a repeater, an inverter, a bias resistor, a reference resistor, and a digital-to-analog converter. The repeater's input is connected to the controller's first terminal, its output is connected to the reference resistor's first terminal, and the reference resistor's second terminal is connected to the inverting input of the intermediate operational amplifier. The inverting input of the intermediate operational amplifier is also connected to the output of the digital-to-analog converter via a bias resistor, and the input of the digital-to-analog converter is connected to the third terminal (group of terminals) of the controller. The non-inverting input of the intermediate operational amplifier is connected to the fifth terminal of the controller, its output is connected to the non-inverting input of the output operational amplifier via an inverter, and the inverting input of the output operational amplifier is connected to the second terminal of the controller.

[0020] The main drawback of this conventional solution is that it does not allow the use of variable resistors (such as photoresistors, thermistors, or digital potentiometers) for control.

[0021] Another conventional controller for the resistance in the circuit section is disclosed in patent no. DE3239309, dated April 26, 1984.

[0022] This conventional controller for resistance in the circuit section is, - The first terminal of the controller is used to connect the circuit to the high-potential terminal of the ECR, - The second terminal of the controller is used to connect the circuit to the first terminal of the current-voltage converter, which is part of the ECR, - The third terminal of the controller is used to connect the circuit to a control voltage source designed as a digital-to-analog converter, - The fourth terminal of the controller is used to connect the circuit to the second terminal of the control voltage source, - The fifth terminal of the controller is used to connect the circuit to the low-potential terminal of the ECR, - The sixth terminal of the controller, which acts as an output and is used to connect the circuit to the control input of the active element, which is part of the ECR. This includes (see Figure 2 in the above publication).

[0023] This conventional controller further includes an operational amplifier and an analog voltage-current divider, The inverting input of the operational amplifier is connected to the second terminal of the controller, and the non-inverting input is connected to the output of the analog voltage-current divider.

[0024] The main drawback of this conventional solution is that it does not allow the use of variable resistors (such as photoresistors, thermistors, or digital potentiometers) for control.

[0025] EP3182243A1, dated June 21, 2017, discloses a conventional controller for the resistance of a circuit component, the most similar analogue (prototype) to the present invention, which is: - The first terminal of the controller is used to connect the circuit to the high-potential terminal of the ECR, - The second terminal of the controller is used to connect the circuit to the first terminal of the detection resistor, which is part of the ECR. - The third terminal of the controller is used to connect the circuit to the first terminal of the control resistor, - The fourth terminal of the controller is used to connect the circuit to the second terminal of the variable control resistor, - The fifth terminal of the controller is used to connect the circuit to the low-potential terminal of the ECR, - The sixth terminal of the controller, which acts as an output and is used to connect the circuit to the control input of the active element, which is part of the ECR. This includes (see Figure 1 of the above publication, which is the same as Figure 1 of this application).

[0026] Conventional controllers further include an operational amplifier, a reference resistor, a constant voltage source, and an uncontrollable current generator. The non-inverting input of the operational amplifier is connected to the fourth terminal of the controller and to the first terminal of the reference resistor, while the second terminal of the reference resistor is connected to the fifth terminal of the controller.

[0027] The inverting input of the operational amplifier is connected to the second terminal of the controller.

[0028] The output of the operational amplifier is connected to the controller's sixth terminal.

[0029] The first and third terminals of the controller are interconnected and further connected to the output of an uncontrollable current generator, the input of which is connected to the positive terminal of a constant voltage source.

[0030] The main drawback of this conventional solution is that it does not allow the direct use of a digital potentiometer as a variable control resistor.

[0031] Digitally controlled potentiometers have neither an active element nor a sensing resistor, and are therefore not considered to be closely related to prior art.

[0032] Therefore, there is a need in this field for an ECR controller that allows for precise setting of resistance (even relatively small) for a given circuit portion over a wide range, and that enables the use of various control resistors, including digital potentiometers, to set the required resistance. [Overview of the project]

[0033] The objective of the present invention is to create a controller for ECR that overcomes the shortcomings of conventional solutions, enables precise setting of resistance (even relatively small) for a given circuit portion over a wide range, and allows the use of various control resistors, including digital potentiometers, to set the required resistance.

[0034] Technical results that were previously considered impossible to achieve with conventional solutions are related to the use of digital potentiometers as variable control resistors to obtain low or extremely low resistance in ECRs that can be used within a wide range of operating voltages and currents.

[0035] Where the specification and claims state that one element is “coupled” to another element, that element may be “directly coupled” to the other element, or it may be “electrically coupled” to the other element via a third element.

[0036] Furthermore, unless explicitly stated otherwise, the term "includes," and its variations such as "includes (third person singular present)" and "includes (present participle)," are understood to mean that they include the element being described but do not exclude other elements.

[0037] In one configuration, an electronic controller for the ECR is provided (see, for example, Figure 2), which may include a current generator that outputs an output current, an amplifier that receives an input voltage proportional to the output current and outputs the amplified input voltage to the first input of an adder, a voltage divider including a bias resistor and a reference resistor connected in series between the high-potential and low-potential terminals of the ECR, and a buffer stage that receives the output of the ECR's sensing resistor and outputs the buffered voltage to the current generator and the second input of the adder, the adder which outputs the added voltage. Furthermore, the electronic controller for the ECR may include an operational amplifier that receives the divided voltage at the first input, the added voltage at the second input, and outputs a control voltage to the active element of the ECR.

[0038] Optionally, a variable control resistor is connected to the low-potential terminal of the ECR on one side and to the current output on the second side, with the input voltage being the voltage across the variable control resistor. Optionally, the active element is a MOSFET. Optionally, the current generator is a controllable current generator. Optionally, the active element of the ECR and the sense resistor are connected in series.

[0039] Optionally, a controllable current generator (see, for example, Figure 3) includes: a second operational amplifier that receives the output voltage of a buffer stage and a voltage proportional to the resistance of a first resistor of the controllable current generator; a first transistor that receives the output voltage of the second operational amplifier and outputs a master current to the first resistor; a second resistor connected in series between the supply voltage and the first transistor, the common node of which is connected to the first input of a third operational amplifier; a third resistor connected in series between the supply voltage and the second transistor, the common node of which is connected to the second input of a third operational amplifier; and a second transistor that receives the output voltage of the third operational amplifier and outputs a controllable output current of the controllable current generator.

[0040] In an alternative configuration, the ECR, including the controller, may include a current generator that outputs an output current, an amplifier that receives an input voltage proportional to the output current and the value of a variable control resistor and outputs the amplified input voltage to the first input of an adder, a voltage divider including a bias resistor and a reference resistor connected in series between the high-potential and low-potential terminals of the ECR, an active element and a sense resistor connected in series between the high-potential and low-potential terminals of the ECR, a buffer stage that receives the output of the sense resistor of the ECR and outputs the buffered voltage to the current generator and to the second input of an adder that outputs the added voltage, and an operational amplifier that receives the divided voltage at the first input, receives the added voltage at the second input, and outputs a control voltage to the active element of the ECR.

[0041] Optionally, a variable control resistor is connected to the low-potential terminal of the ECR on one side and to the current output on the second side, with the input voltage being the voltage across the variable control resistor. Optionally, the active element of the ECR is a MOSFET. Optionally, the current generator is a controllable current generator.

[0042] Optionally, the controllable current generator includes a second operational amplifier that receives the output voltage of a buffer stage and a voltage proportional to the resistance of a first resistor of the controllable current generator; a first transistor that receives the output voltage of the second operational amplifier and outputs a master current to the first resistor; a second resistor connected in series between the supply voltage and the first transistor, the common node of which is connected to the first input of a third operational amplifier; a third resistor connected in series between the supply voltage and the second transistor, the common node of which is connected to the second input of a third operational amplifier; and a second transistor that receives the output voltage of the third operational amplifier and outputs a controllable output current of the controllable current generator.

[0043] Further features and advantages of the present invention are described in the following description, some of which are evident from that description, and some can be learned by carrying out the invention. The advantages of the present invention will be realized and obtainable by the structure and accompanying drawings, which are particularly pointed out in the description and claims.

[0044] It should be understood that both the general description above and the detailed description below are for illustrative and explanatory purposes only and are intended to provide a further description of the claimed invention.

[0045] The attached drawings are included to further illustrate the invention, are incorporated to form part of this specification, illustrate embodiments of the invention, and are used together with the description to illustrate the principles of the invention. [Brief explanation of the drawing]

[0046] [Figure 1] Figure 1 illustrates a conventional controller (prior art). [Figure 2]Figure 2 shows an exemplary embodiment of a device for controlling the active element of an ECR, which is controlled by a variable control resistor such as a mechanical potentiometer, photoresistor, thermistor, or digital potentiometer. [Figure 3] Figure 3 shows an exemplary embodiment of a controllable current generator that can be used in a controller. [Figure 4] Figure 4 illustrates the experimental results of device prototyping. [Modes for carrying out the invention]

[0047] Hereinafter, preferred embodiments of the present invention will be referred to in detail, examples of which are illustrated in the accompanying drawings.

[0048] To achieve the above technical results, the device proposed here is - The first terminal 1 of the controller 220 is used to connect the controller 220 to the first terminal of the variable control resistor Rc, - The second terminal 2 of the controller 220 is used to connect the controller 220 to the first terminal of the detection resistor Rsense, which is part of the ECR222, - The third terminal 3 of the controller 220 is used to connect the controller 220 to the control terminal of the active element 224, which is part of the ECR222, - The fourth terminal 4 of the controller 220 is used to connect the controller 220 to the second terminal of the variable control resistor Rc, - The fifth terminal 5 of the controller 220 is used to connect the controller 220 to the low-potential terminal 12 of the ECR222, - The sixth terminal 6 of the controller 220 is used to connect the controller 220 to the high-potential terminal 10 of the ECR222, - Operational amplifier 208, - Reference resistor Rref, - Constant voltage source (e.g., battery) 214 and Includes, The non-inverting input of the operational amplifier 208 is connected to the first terminal of the reference resistor Rref, the second terminal of the reference resistor Rref is connected to the fifth terminal 5 of the controller 220, and the output of the operational amplifier 208 is connected to the third terminal 3 of the controller 220 (see Figure 2, which shows an exemplary embodiment of the device (controller 220) for controlling the ECR222).

[0049] Controller 220 is, - Bias resistor Rbias, - Amplifier 204 and, - Adder 206 and, - Buffer stage 210, - Controllable current generator 212 and Furthermore, - The first terminal of bias resistor Rbias is connected to terminal 6 of device 220, and the second terminal of bias resistor Rbias is connected to the non-inverting input of operational amplifier 208. - The input of amplifier 204 is connected to the first terminal 1 of the device, the output of amplifier 204 is connected to the first input of adder 206, and the output of adder 206 is connected to the inverting input of operational amplifier 208. - The device's second terminal 2 is connected to the input of the buffer stage 210, and the output of the buffer stage 210 is connected to both the second input of the adder 206 and the control input of the controllable current generator 212. - The power input 22 of the controllable current generator 212 is connected to the positive terminal of the DC power supply 214, and the negative terminal of the DC power supply 214 is connected to the low-potential terminal of the ECR. - The output 26 of the controllable current generator 212 is connected to the first terminal 1 of the device and is designed to send a control action, which in turn causes the resistance of the variable control resistor Rc to change.

[0050] By adding the bias resistor Rbias, amplifier 204, adder 206, buffer stage 210, and controllable current generator 212 in corresponding connections according to the proposed invention, a constant potential is maintained at the non-inverting input of the operational amplifier 208 during the conversion of the voltage U1 at the high-potential terminal 10 of the ECR222. U1' = U1 × Rref / (Rref + Rbias) (1) It becomes possible to create Here, Rbias is the resistance of the bias resistor, and Rref is the resistance of the reference resistor.

[0051] At the same time, the inverting input of the operational amplifier 208 receives a total signal S, which is composed of the following augments.

[0052] The first augment is sent from the first terminal 1 of the proposed controller 220, through the amplifier 204, to the first input of the adder 206, with the amplification coefficient K' being applied. The first augment is represented by the amplified voltage drop across the variable control resistor Rc, which is caused by the current Icg produced by the controllable current generator 212, i.e., S1 = K' × Icg × Rc (2) That is the case.

[0053] The second augment is sent from the second terminal 2 of the proposed controller 220, through the buffer stage 210, to the second input of the adder 206, where the unitary transfer ratio is given. The second augment is represented by the voltage U2 of the sense resistor Rsense, which is part of the ECR222 controlled by the proposed controller 220.

[0054] This voltage is calculated using the following formula U2=I0×Rsense (3) Defined using, Here, Rsense is the value of the detection resistor, which can be as small as possible when considering implementation. I0 is the amount of current flowing through the ECR222, and is determined by the active element 224, which is part of the ECR222.

[0055] Therefore, S2 = U2 = I0 × Rsense (4) Therefore, the total signal S at the inverting input of the operational amplifier 208 is S=S1+S2=K'×Icg×Rc+I0×Rsense (5) This is the result.

[0056] Now, considering that the current Icg of the controllable current generator 212 depends on the voltage U2 sent from the output of the buffer stage 210 to the control input 24 of the controllable current generator 212, this means that Icg=U2×Gcg=I0×Rsense×Gcg (6) Here, Gcg is the coefficient for converting the control voltage U2 to a current equal to the conductivity.

[0057] Therefore, based on equations (5) and (6), S=K'×I0×Rsense×Gcg×Rc+I0×Rsense=I0×Rsense×(1+K'×Rc×Gcg) (7) This is the result.

[0058] The difference between U1' and S at the output of the operational amplifier 208 is sent as a control signal Ucontr (Ucontr = U1' - S) to the third terminal 3 of the controller 220, and therefore to the output of the proposed controller. This third terminal 3 of the controller 220 is used to connect the circuit to the control terminal of the active element 224. Since the amplification coefficient in this feedback chain (operational amplifier 208 - active element 244 of the ECR - sense resistor Rsense - buffer stage 210 - adder 206 - operational amplifier 208) is high, the relationship "U1' ≈ S" is true with practical accuracy.

[0059] Therefore, referring to equations (1) and (7), U1×Rref / (Rref+Rbias)=I0×Rsense×(1+K'×Rc×Gcg) (8) Therefore, regarding the resistance of the ECR (see Figure 2) between the high-potential terminal 10 and the low-potential terminal 12, R0=U1 / I0=Rsense×(1+K'×Rc×Gcg) / (1+Rbias / Rref) (9) This leads to the conclusion that...

[0060] Equation (9) shows that the resistance of the ECR according to the present disclosure is proportional to the resistance of the sensing resistor Rsense and is directly proportional to the control action, where the control action corresponds to the resistance of a variable control resistor Rc (e.g., a digital potentiometer).

[0061] Equation (9) also shows the following relationship: Rc×(K'×Gcg)<<1 and Rbias ≈ Rref (10) This demonstrates that if both conditions are true, it is possible to obtain a low or extremely low Ro value with a low Rsense.

[0062] The variable control resistor Rc, as in conventional solutions, can be represented by a mechanical potentiometer, photoresistor, or thermistor.

[0063] The proposed circuit has the advantage of using a digital potentiometer as a control resistor to obtain low or extremely low resistance in the ECR, which can be used within a wide range of operating voltages and currents, and thus achieves the above technical results.

[0064] The controller of this invention for the ECR222, as shown in Figure 2, functions as follows:

[0065] When the control action, which corresponds to the change in resistance of a variable control resistor Rc (e.g., a digital potentiometer), changes, the voltage U Rc The signal from the resistor passes through amplifier 204, and the amplification coefficient K' is given, and the first augmented value "S1 = K' × U RcThe second augmentant S2, represented by voltage U2, is sent from the sense resistor Rsense, which is part of the ECR222 controlled by the proposed controller 220, through the buffer stage 210 to the second input of the adder 206. This voltage is determined using equation (3), i.e., "U2 = I0 × Rsense", and therefore "S2 = I0 × Rsense" (see equation (4)), where Rsense is the value of the sense resistor, which can be as small as possible when considering implementation.

[0066] As described above, voltage U2 is equal to the current drop across the sensing resistor Rsense caused by the current I0 flowing through ECR222. In reality, the current I0 flows through the chain "high-potential terminal 10 of ECR222 - active element 224 - sensing resistor Rsense connected in series with active element 224 - low-potential terminal 12 of ECR222", which is due to the potential difference U1 between the high-potential terminal 10 and the low-potential terminal 12 of ECR222.

[0067] Therefore, the voltage "K' × U Rc " and "U2", that is, "K'×U Rc =S1" and "U2=S2=I0×Rsense" By summing these, the intermediate signal is obtained at the output of adder 206. S = S1 + S2 = K' × U Rc +I0×Rsense (11) A new generation is created. This is then received by the inverting input of the operational amplifier 208.

[0068] Simultaneously, a constant potential U1' is sent from terminal 6 of device 220 through the voltage divider formed by the bias resistor Rbias and the reference resistor Rref to the non-inverting input of the operational amplifier, which is, U1' = U1 / (1 + Rbias / Rref) They become equal as shown (see equation (1)).

[0069] The difference between S and U1' is sent from the output of the operational amplifier 208 to the third terminal 3 of the proposed controller 220, and therefore to the output of the proposed controller 220. The third terminal 3 is used to connect to the control terminal of the active element 224, which is part of the ECR 222, so that the control voltage Ucontr (Ucontr = U1' - S) is sent from the output of the proposed controller 220 to the control terminal of the active element 224.

[0070] However, if the value of the intermediate signal S at the output of adder 206 is higher than the voltage U1', the voltage Ucontr at the control terminal of active element 224 causes active element 224 to be partially closed, easing the current I0 and causing the voltage U2 to drop. This voltage passes through buffer stage 210 and is sent to the second input of adder 206 as the second augmented "S2 = I0 × Rsense" (see equation (4) for details). Furthermore, the voltage U2 is sent to the control input 24 of controllable current generator 212, which easing its current Icg according to equation (6) "Icg = U2 × Gcg = I0 × Rsense × Gcg", where Gcg is the coefficient for converting the control voltage U2 to a current equal to the conductivity.

[0071] Reducing the current Icg of the controllable current generator 212 reduces the voltage drop across the variable control resistor Rc (e.g., a digital potentiometer), and thus, after being amplified K' times by amplifier 204, S1=K'×Icg×Rc=I0×Rsense×Gcg×K'×Rc (12) This will soften the first augment at the first input of adder 206 (see equations (2) and (6)).

[0072] In adder 206, the augendants S1 and S2 are added together to generate an intermediate signal S at the output of adder 206. For details, please refer to equation (7) "S = I0 × Rsense × (1 + K' × Rc × Gcg)".

[0073] As described above, the intermediate signal S is mitigated by the decrease in current I0.

[0074] Due to the high amplification coefficient of the operational amplifier 208, this process persists until the intermediate signal S at the inverting input of the operational amplifier 208 equals the voltage U1' at the non-inverting input of the operational amplifier.

[0075] Conversely, if the value of the intermediate signal S at the output of adder 206 is lower than the voltage U1', the voltage Ucontr at the control terminal of active element 224 causes active element 224 to be partially open, increasing the current I0 and thus increasing the voltage U2. This current passes through the buffer stage 210 and is sent to the second input of adder 206 as the second augmented "S2 = I0 × Rsense" (see equation (4)). Furthermore, the voltage U2 is sent to the control input 24 of controllable current generator 212, where it increases the current Icg according to equation (6) "Icg = U2 × Gcg = I0 × Rsense × Gcg".

[0076] The augmented S2 also increases, but for details, please refer to equation (12) "S1 = I0 × Rsense × Gcg × K' × Rc".

[0077] By adding the increasing adenants S1 and S2 in the adder 206, an intermediate signal S, as described by equation (7), is generated at the output of the adder 206. The intermediate signal S increases due to the increase in current I0 as described above.

[0078] Due to the high amplification coefficient of the operational amplifier 208, this process continues until the intermediate signal S at the inverting input of the operational amplifier 208 becomes equal to the voltage U1' at the non-inverting input of the operational amplifier, i.e., S = U1'.

[0079] Therefore, with respect to the claimed invention, the relationship "S=U1'" is always true with practical accuracy due to the high-gain feedback loop of "operational amplifier 208 - active element 224 of ECR222 - sense resistor Rsense - buffer stage 210 - adder 206 - operational amplifier 208".

[0080] Alternatively, by substituting the corresponding values ​​from (1) and equation (11), equation (8) U1×Rref / (Rref+Rbias)=I0×Rsense×(1+K'×Rc×Gcg) You can obtain it again.

[0081] Equation (8) is highly reliable as true due to high-gain feedback, even under various destabilizing factors, including wide temperature fluctuations.

[0082] If we consider the resistance R0 between the high-potential terminal 10 and the low-potential terminal 12 of the ECR222 to be the ratio of the voltage U1 to the current I0 flowing through the chain (high-potential terminal 10 - active element 224 - sensing resistor Rsense connected in series with the active element 224 - low-potential terminal 12), then R0 = U1 / I0 (13) This is the result.

[0083] The relationship between (8) and (13) is the resistance between the high-potential terminal 10 and the low-potential terminal 12 of the ECR222. R0=U1 / I0=Rsense×(1+K'×Rc×Gcg) / (1+Rbias / Rref) This produces the following, which corresponds to equation (9).

[0084] Therefore, by generating an intermediate signal at the output of the adder 206, as in the case of equation (7) "S = I0 × Rsense × (1 + K' × Rc × Gcg)", sending this signal to the second (inverting) input of the operational amplifier 208, and sending the potential "U1' = U1 / (1 + Rbias / Rref)" (see equation (1)) to the first (non-inverting) input of the operational amplifier 208, and ensuring that the equivalent "S = U1'" is true due to high-gain feedback, it is shown that the resistance R0 of the ECR is directly proportional to the resistance of the sensing resistor Rsense, and also proportional to the control action corresponding to the resistance of the variable control resistor Rc (e.g., a digital potentiometer).

[0085] Equation (9) means that low and very low R0 values ​​can be obtained with the relatively high current I0 provided by the active element 224. Therefore, to control the resistance of the circuit portion, a control action corresponding to the resistance of a variable control resistor Rc (e.g., a digital potentiometer) is used, and the resistance of ECR ​​is proportional to the control action corresponding to the value of the variable control resistor Rc (e.g., a digital potentiometer).

[0086] In Figure 3, the elements of the controllable current generator 212 are as follows: -302- Second operational amplifier, -303-Third operational amplifier, -311-1st MOSFET transistor, -312-2nd MOSFET transistor, -Rcg1- First resistor of controllable current generator 212, -Rcg2- Second resistor of controllable current generator 212, -Rcg3- Third resistor of controllable current generator 212 That is the case.

[0087] The controllable current generator 212 in Figure 3 functions as follows:

[0088] The signal S2 (control signal for the controllable current generator 212) is sent to the control input, and then to the non-inverting input (+) of the second operational amplifier 302, where the output of the operational amplifier 302 is connected to the gate of the first MOSFET transistor 311. The source of the first MOSFET transistor 311 is connected to the inverting input (-) of the second operational amplifier 302 of the controllable current generator 212, and to the first terminal of the first resistor Rcg1. This refers to terminal 28 of the controllable current generator 212 and It is connected to the low-potential terminal 12 of the ECR (see also Figure 2). Current Icg1 flows through the drain-source chain of the first MOSFET transistor 311, thereby, Ucg1 = Icg1 × Rcg1 (14) This causes a voltage drop across the first resistor Rcg1 of the controllable current generator 212.

[0089] Since the feedback loop between the second operational amplifier 302 and the first MOSFET transistor 311 has high gain, the signal S2 at the non-inverting input (+) of the second operational amplifier 302 and the voltage Ucg1 at its inverting input (-) can be considered equal for practical purposes, and therefore, S² = Ucg¹ (15) It will look like this.

[0090] Therefore, the current flowing through the first MOSFET transistor 311 is: Icg1 = S2 / Rcg1 (16) And this is, Ucg2 = Icg1 × Rcg2 (17) This causes a voltage drop across the second resistor Rcg2 of the controllable current generator 212.

[0091] The first terminal of the second resistor Rcg2 is connected to terminal 22 of the controllable current generator 212 which receives the supply voltage E, and the second terminal of the second resistor Rcg2 is connected to the non-inverting input (+) of the third operational amplifier 303, so there, U +303 =E-Ucg2 (18) A voltage as shown is generated.

[0092] The output of the third operational amplifier 303 is connected to the gate of the second MOSFET transistor 312, the drain of said transistor is connected to the inverting input (-) of the third operational amplifier 303 and to the first terminal of the third resistor Rcg3, and the second terminal of the third resistor Rcg3 is connected to terminal 22 of the controllable current generator 212 that receives supply voltage E.

[0093] The output current Icg of the controllable current generator 212 flows through the drain-source path of the second MOSFET transistor 312 to terminal 26 of the controllable current generator 212, Ucg3=Icg×Rcg3 (19) causing a voltage drop across the third resistor Rcg3 of the controllable current generator 212 as shown above.

[0094] As a result, the inverting input (-) of the third operational amplifier 303 receives the following voltage U -303 =E-Ucg3 (20) from the first terminal of the third operational amplifier 303.

[0095] Since the feedback looping through both the third operational amplifier 303 and the second MOSFET transistor 312 has high gain, the voltage at the non-inverting input (+) of the third operational amplifier 303 and the voltage at the inverting input (-) thereof can be considered equal for practical purposes, therefore, U +303 =U -303 (21) holds as shown above.

[0096] Therefore, referring to formula (18) and formula (20), Ucg2=Ucg3 (22) the above formula holds.

[0097] Further, considering formula (17) and formula (19), Icg1×Rcg2=Icg×Rcg3 (23) the above formula holds.

[0098] Therefore, the output current Icg of the controllable current generator 212 is Icg = Icg1 × Rcg2 / Rcg3 (24) This is the result.

[0099] And since Icg1 depends on the control signal S2 (see equation (16)), the result is Icg=S2×Rcg2 / (Rcg1×Rcg3) (25) This is the result.

[0100] Alternatively, since signal S2 is equal to the voltage U2 received from the sensing resistor Rsense, which is part of the ECR222, the final result is: Icg=U2×Rcg2 / (Rcg1×Rcg3) (26) And so, Furthermore, this current does not depend on the resistance of the variable control resistor Rc located outside the controllable current generator 212, but only on the control voltage U2 across the internal resistance of the resistor in the controllable current generator 212 and the sensing resistor Rsense.

[0101] The following values Gcg = Rcg² / (Rcg¹ × Rcg³) (27) This characterizes the coefficients for converting the control voltage U2 to a current that is equal to the conductivity and used in determining the resistance of ECR222, in accordance with this disclosure. Thus, for example, the controllable current generator 212 specified according to Figure 3 enables the proposed controller 220 to function in such a way as to achieve the technical results described above.

[0102] Controllable current generators can be implemented in various ways, for example, as described in the description and drawing "0.5A to 4A Voltage Controlled Current Source" in LINEAR TECHNOLOGY CORPORATION's 2002 LT1789 "Micropower, Single Supply Rail-to-Rail Output Instrumentation Amplifiers" (see also https: / / www.analog.com / ru / products / lt1789.html#product-overview).

[0103] Furthermore, a controllable current generator can be implemented, for example, according to the article "How should I design variable current source of 4-20mA with 24Vdc input?", for which you can refer to "Electrical Engineering Stack Exchange" or "https: / / electronics.stackexchange.com / questions / 72192 / how-should-i-design-variable-currentsource-of-4-20ma-with-24vdc-input?rq=1".

[0104] Furthermore, the controllable current generator 212 can be designed based on the IC LT6552, as described by Jim Williams in "Voltage controlled current source - ground referred input and output" in the 2013 issue of "Analog Circuit Design" (https: / / www.sciencedirect.com / topics / engineering / controlled-current-source), and based on many other options.

[0105] The voltage divider can be implemented as a resistor divider, as a divider including two transistors connected in series, or in any other way that allows a deterministic portion of the voltage from the high-potential terminal 10 of the ECR222 to be sent to the non-inverting input of the operational amplifier 208.

[0106] The voltage divider can also be configured as an external component of the controller 220, connected to the controller 220 via a separate terminal, thereby preventing voltage from being sent from the high-potential terminal 10 of the ECR222 to the controller 220.

[0107] The amplifier 204, buffer stage 210, and adder 206 can be implemented in various ways that enable the performance of the proposed device.

[0108] The controller 220 can be made using standard individual components or integrated circuits, including operational amplifiers, transistors, and resistors, as well as ASICs. For example, the amplifier 204, buffer 210, and current generator 212 can be made using integrated circuits such as OPA189, TLV9002IDR, MCP6002-E / SN, and many other integrated circuits. The main parameter is preferably an open-loop gain (R) of at least 100 dB. L The impedance should be R = 10kΩ, with a gain-bandwidth product of at least 1MHz, and rail-to-rail input and output. Similar components can be used for the operational amplifier 208. For the controllable current generator 212, transistors such as NTNUS3171PZ, NX3020NAK, and similar ones can be used, with parameters up to 5.5 ohms. DS (On), the drain current I0 is at least 100mA.

[0109] Other components of the ECR222 (e.g., adder 206, voltage source 214) are known in the art and can be implemented in any number of known ways.

[0110] Regarding the nominal value of the resistor, Rbias is in the range of 100-200k ohms. Rref is in the range of 50-100k ohms. That is the case.

[0111] Rcg1, Rcg2, and Rcg3 typically range from 200 ohms to 1 k ohm.

[0112] Rsense depends on the nominal desired value of the ECR222, which is typically 10 milliohms or more (e.g., up to 100 ohms). The STT6N3LLH6 transistor or its analogues have their R DS As long as the (ON) value is approximately smaller than the nominal ECR222 value, it can be used as an active element.

[0113] The proposed controller 220 for ECR222 can be manufactured, for example, as a chip, chip assembly, or microplate. ECR222 can also be manufactured, for example, as a chip, chip assembly, or microplate.

[0114] A preferred embodiment of the controller 220 for the ECR222 is in the form of an integrated circuit, which allows for a substantial reduction in size and manufacturing cost. For relatively low-power ECRs (where the total power wasted by the active element and sense resistor is up to about 1-2 watts), it is preferable to implement the controller, active element, and sense resistor as a single integrated circuit. In either case, the voltage divider can be external or internal to this chip.

[0115] Experimental results The proposed controller 220 shown in Figures 2 and 3 was prototyped to verify whether it could achieve the objectives of the present invention.

[0116] The results of the prototype were, Supply voltage: 5V ± 5% Minimum resistance of a variable control resistor Rc (e.g., a digital potentiometer): 100 ohms Maximum resistance of a variable control resistor Rc (e.g., a digital potentiometer): 10,000 ohms Minimum resistance R of ECR 0min :383.5 ohms Maximum resistance of ECR ​​R 0max :26225.9 ohms ECR resistance adjustment range 68,4x That was the case.

[0117] The nonlinearity of the dependence between the resistance of the ECR222 and the resistance of the resistor Rc (e.g., a digital potentiometer) does not exceed 1.4%.

[0118] The dependence between the resistance R0 of the ECR222 and the resistance of the variable control resistor Rc is shown as a straight line in Figure 4. The measured resistance values ​​are indistinguishable from predicted / estimated values.

[0119] Therefore, it should be understood that the present invention successfully achieves the objective of the present invention, which includes using a digital potentiometer as a variable control resistor to obtain low or extremely low resistance in an ECR that can be used within a wide range of operating voltages and currents.

[0120] However, the present invention is not limited to those.

[0121] Having described preferred embodiments, it will be apparent to those skilled in the art that the specific advantages of the described methods and apparatus are achieved.

[0122] While the present invention has been described in relation to exemplary embodiments that are considered practical at present, it will be understood that the present invention is not limited to the disclosed embodiments, but rather intended to cover a variety of variations and equivalent arrangements within the spirit and scope of the appended claims.

[0123] The drawings and description of this invention are for illustrative purposes only and do not limit the scope of its implementation.

[0124] The present invention is further defined by the appended claims.

Claims

1. A controller (220) for the ECR (222), First operational amplifier (208), Reference resistor (Rref), A constant voltage source (214), Bias resistor (RBias), Adder (206), A controllable current generator (212), The first terminal (1) of the controller (220) for connecting to the first terminal of an external variable control resistor (Rc), The second terminal (2) of the controller (220) receives a feedback signal from a common node between an external sense resistor (Rsense) and an external active element (224), The third terminal (3) of the controller (220) for connecting to the control terminal of the external active element (224), The fourth terminal (4) of the controller (220) for connecting to the second terminal of the external variable control resistor (Rc), The fifth terminal (5) of the controller (220) for connecting to the low-potential terminal (12) of the ECR (222), The sixth terminal (6) of the controller (220) for connecting to the high-potential terminal (10) of the ECR (222), The fourth terminal (4) and the fifth terminal (5) of the controller (220) are connected to each other and are also connected to the second terminal (28) of the controllable current generator (212). The output of the first operational amplifier (208) is connected to the third terminal (3) of the controller (220), The first terminal of the reference resistor (Rref) is connected to the non-inverting input of the first operational amplifier (208), The second terminal of the reference resistor (Rref) is connected to the fifth terminal (5) of the controller (220), The first terminal of the bias resistor (RBias) is connected to the sixth terminal (6) of the controller (220), The second terminal of the bias resistor (RBias) is connected to the non-inverting input of the first operational amplifier (208), The first input of the adder (206) is connected to the first terminal (1) of the controller (220), The second input of the adder (206) is connected to the second terminal (2) of the controller (220), The output of the adder (206) is connected to the inverting input of the first operational amplifier (208), Equipped with, The controllable current generator (212) comprises a second operational amplifier (302), a third operational amplifier (303), a first transistor (311), a second transistor (312), a first resistor (Rcg1), a second resistor (Rcg2), and a third resistor (Rcg3), and the control input (24) of the controllable current generator (212) is connected to the second terminal (2) of the controller (220), and the second operational amplifier (30 2) is connected to the non-inverting input of the second operational amplifier (302), the inverting input of the second operational amplifier (302) is connected to the common node between the source of the first transistor (311) connected in series and the first terminal of the first resistor (Rcg1), the second terminal of the first resistor (Rcg1) is connected to the second terminal (28) of the controllable current generator (212), and the output of the second operational amplifier (302) is connected to the gate of the first transistor (311), The output (26) of the controllable current generator (212) is connected to the first terminal (1) of the controller (220) and also to the source of the second transistor (312). A controller in which the output of the third operational amplifier (303) is connected to the gate of the second transistor (312), the non-inverting input of the third operational amplifier (303) is connected to a common node between the drain of the first transistor (311) connected in series and the second terminal of the second resistor (Rcg2), the inverting input of the third operational amplifier (303) is connected to a common node between the drain of the second transistor (312) connected in series and the first terminal of the third resistor (Rcg3), and the common node between the first terminal of the second resistor (Rcg2) and the second terminal of the third resistor (Rcg3) is connected to the first terminal (22) of the controllable current generator (212) in order to connect to the constant voltage source (214) to supply power to the controllable current generator.

2. A controller (220) according to claim 1, wherein the connection of the second terminal (2) of the controller (220) to the second input of the adder (206) is made through a buffer stage (210).

3. A controller (220) according to claim 1, wherein the connection of the first terminal (1) of the controller (220) to the first input of the adder (206) is made through an amplifier (204).

4. An ECR (222) used in conjunction with a variable control resistor (Rc), High-potential terminal (10), Active element (224), A resistor sense (Rsense), Low-potential terminal (12) and The controller (220) according to claim 1, Equipped with, The high-potential terminal (10), the active element (224), the sensing resistor (Rsense), and the low-potential terminal (12) are connected in series. The high-potential terminal (10) is connected to the sixth terminal (6) of the controller (220). The low-potential terminal (12) is connected to the fifth terminal (5) of the controller (220). The control terminal of the active element (224) is connected to the third terminal (3) of the controller (220). The common node between the detection resistor (Rsense) and the active element (224) is connected to the second terminal (2) of the controller (220). The first terminal (1) of the controller (220) is designed to be connected to the first terminal of the external variable control resistor (Rc), An ECR is designed such that the fourth terminal (4) of the controller (220) is connected to the second terminal of the external variable control resistor (Rc).

5. An ECR (222) according to claim 4, wherein the active element (224) is a transistor.

6. An integrated circuit (IC) for a controller (220) for an ECR (222), First operational amplifier (208), Reference resistor (Rref), Bias resistor (RBias), A first terminal (1) is designed to be connected to the first terminal of an external variable control resistor (Rc), A second terminal (2) is designed to receive a feedback signal from a common node between an external sense resistor (Rsense) and an external active element (224), A third terminal (3) is designed to be connected to the control terminal of the external active element (224), A fourth terminal (4) is designed to be connected to the second terminal of the external variable control resistor (Rc), A fifth terminal (5) is designed to be connected to the low-potential terminal (12) of the ECR (222), A sixth terminal (6) is designed to be connected to the high-potential terminal (10) of the ECR (222), Adder (206), A controllable current generator (212) comprising a second operational amplifier (302), a third operational amplifier (303), a first transistor (311), a second transistor (312), a first resistor (Rcg1), a second resistor (Rcg2), and a third resistor (Rcg3), wherein the control input (24) of the controllable current generator (212) is connected to the second terminal (2) and is also designed to be connected to the non-inverting input of the second operational amplifier (302), the inverting input of the second operational amplifier (302) is connected to a common node between the source of the first transistor (311) and the first terminal of the first resistor (Rcg1) which are connected in series, and the second terminal of the first resistor (Rcg1) is connected to the second terminal (28) of the controllable current generator (212), The output of the second operational amplifier (302) is connected to the gate of the first transistor (311), the output (26) of the controllable current generator (212) is connected to the first terminal (1) and is designed to be connected to the source of the second transistor (312), the output of the third operational amplifier (303) is connected to the gate of the second transistor (312), and the non-inverting input of the third operational amplifier (303) is connected to the common node of the drain of the first transistor (311) connected in series and the second terminal of the second resistor (Rcg2), The inverting input of the third operational amplifier (303) is connected to the common node between the drain of the second transistor (312), which is connected in series, and the first terminal of the third resistor (Rcg3). The first terminal of the second resistor (Rcg2) and the second terminal of the third resistor (Rcg3) are connected to the first terminal (22) of the controllable current generator (212), which is designed to supply power to the controllable current generator (212). A controllable current generator (212), The output of the first operational amplifier (208) is connected to the third terminal (3), The first terminal of the reference resistor (Rref) is connected to the non-inverting input of the first operational amplifier (208), The second terminal of the reference resistor (Rref) is connected to the fifth terminal (5), The first terminal of the bias resistor (RBias) is connected to the sixth terminal (6), The second terminal of the bias resistor (RBias) is connected to the non-inverting input of the first operational amplifier (208), Equipped with, The fourth terminal (4) and the fifth terminal (5) are connected to each other and are connected to the second terminal (28) of the controllable current generator (212) inside the integrated circuit (IC), The first input of the adder (206) is connected to the first terminal (1) of the controller (220), The second input of the adder (206) is connected to the second terminal (2) of the controller (220), An integrated circuit (IC) in which the output of the adder (206) is connected to the inverting input of the first operational amplifier (208).

7. An integrated circuit (IC) for a controller (220) for an ECR (222), wherein the integrated circuit (IC) is A first terminal (1) is designed to be connected to the first terminal of an external variable control resistor (Rc), A second terminal (2) is designed to receive a feedback signal from a common node between an external sense resistor (Rsense) and an external active element (224), A third terminal (3) is designed to be connected to the control terminal of the external active element (224), A fourth terminal (4) is designed to be connected to the second terminal of the external variable control resistor (Rc), A fifth terminal (5) is designed to be connected to the low-potential terminal (12) of the ECR (222), A sixth terminal (6) is designed to be connected to the high-potential terminal (10) of the ECR (222), First operational amplifier (208), A controllable current generator (212), Adder (206), Equipped with, The controllable current generator (212) comprises a second operational amplifier (302), a third operational amplifier (303), a first transistor (311), a second transistor (312), a first resistor (Rcg1), a second resistor (Rcg2), and a third resistor (Rcg3), wherein the control input (24) of the controllable current generator (212) is connected to the second terminal (2) and is also designed to be connected to the non-inverting input of the second operational amplifier (302), the inverting input of the second operational amplifier (302) is connected to a common node between the source of the first transistor (311) and the first terminal of the first resistor (Rcg1) which are connected in series, and the second terminal of the first resistor (Rcg1) is connected to the second terminal (28) of the controllable current generator (212), The output of the second operational amplifier (302) is connected to the gate of the first transistor (311), and the output (26) of the controllable current generator (212) is connected to the first terminal (1) and also to the source of the second transistor (312). The output of the third operational amplifier (303) is connected to the gate of the second transistor (312), the non-inverting input of the third operational amplifier (303) is connected to the common node between the drain of the first transistor (311) connected in series and the second terminal of the second resistor (Rcg2), and the inverting input of the third operational amplifier (303) is connected to the common node between the drain of the second transistor (312) connected in series and the first terminal of the third resistor (Rcg3). The first terminal of the second resistor (Rcg2) and the second terminal of the third resistor (Rcg3) are connected to the first terminal (22) of the controllable current generator (212), which is designed to supply power to the controllable current generator (212). The non-inverting input of the first operational amplifier (208) is designed to be connected to the midpoint of an external voltage divider comprising a bias resistor (RBias) and a reference resistor (Rref) connected in series between a high-potential terminal and a low-potential terminal, and the output of the first operational amplifier (208) is connected to the third terminal (3). The fourth terminal (4) and the fifth terminal (5) are connected to each other and are connected to the second terminal (28) of the controllable current generator (212) inside the integrated circuit (IC), The first input of the adder (206) is connected to the first terminal (1) of the controller (220), The second input of the adder (206) is connected to the second terminal (2) of the controller (220), An integrated circuit (IC) in which the output of the adder (206) is connected to the inverting input of the first operational amplifier (208).

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