Device for generating at least two electric currents

Abstract

The present invention relates to a device (1) for generating at least two electric currents from a control current (IC), the device (1) comprising: – a first current-generating module (3) comprising at least one resistor (R1), referred to as the first resistor, the first module (3) being configured such that a voltage across the terminals of the first resistor (R1) generates a first current (I1), the voltage applied to the terminals of the first resistor (R1) depending on the control current (IC); – a second current-generating module (5) comprising at least one resistor (R2), referred to as the second resistor, the second module (5) being configured such that a voltage across the terminals of the second resistor (R2) generates a second current (I2); –a switched capacitor-based connection module (7) that connects the first module (3) to the second module (5), the connection module (7) being configured such that the voltage applied to the terminals of the first resistor (R1) is applied to the terminals of the second resistor (R2).

Description

Description Title of the invention: DEVICE FOR GENERATING AT LEAST TWO ELECTRIC CURRENTS

[0001] The present invention relates to the field of generating electric currents to power electronic components, such as capacitive elements.

[0002] Indeed, in the context of certain electronic devices, it is necessary to jointly power components with predetermined current values, that is to say currents with a very small difference between them, for example less than 0.5%, or currents proportional to each other, the ratio of the currents having a substantially constant value, the variation of said ratio being for example less than 0.5%, in order to guarantee the function or the expected result of said electronic components powered by said electrical currents.

[0003] Note that this type of current is also referred to as "mirror currents", and generally requires one or more temperature-dependent electronic components, such as potentiometers, to adjust the values ​​of these mirror currents.

[0004] This type of current generation device is of particular interest in powering sensors, especially capacitive ones (for example, capacitive differential pressure sensors), or in the field of metrology where it is necessary to be able to minimize uncertainties on the values ​​of electrical quantities, such as electrical currents flowing in standard components.

[0005] It is common to use transistor-based circuits, also known as "current mirrors," but these have several drawbacks that can compromise the expected accuracy. Among the issues that can cause the current values ​​generated by the circuit to diverge are the dispersion of the transistors' current gains, the effect of temperature on the transistor(s), and so on. Furthermore, this type of circuit requires adjustments to function correctly, for example, due to the variability of the electronic components used.

[0006] The invention thus aims to solve at least one of the problems mentioned above by proposing a new type of device for generating at least two electric currents from a control current, said device comprising: - a first current generation module comprising at least one resistor, referred to as the first resistor, said first module being configured so that a voltage at terminals of the first resistor generates a first current, the voltage applied across the terminals of the first resistor being a function of the control current; - a second current generation module comprising at least one resistor, referred to as the second resistor, said second module being configured so that a voltage across the terminals of the second resistor generates a second current; - a switched-capacitor linking module that connects the first module to the second module, said linking stage being configured so that the voltage applied across the terminals of the first resistor is duplicated across the terminals of the second resistor.

[0007] The device according to the invention is an alternative to current mirror circuits for generating bound currents. This device is very slightly, if at all, temperature-dependent and requires little or no adjustment. Furthermore, the uncertainty in the generated current values ​​depends primarily on the first and second resistances.

[0008] According to one possible characteristic, the first current generation module includes an operational amplifier, called the first operational amplifier, mounted in bilateral feedback (the operational amplifier comprising two feedbacks, one on each of the inputs of said operational amplifier), said operational amplifier having an inverting input, a non-inverting input and an output, the input of the first module being identified as a dipole whose terminals correspond to the output and the inverting input of said operational amplifier, the output of the first module being identified as a dipole whose terminals correspond to the terminals of the first resistor, the output and the non-inverting input of said operational amplifier being connected respectively to the opposite terminals of said first resistor.

[0009] Advantageously, the first current generation module allows the input voltage of the first module to be duplicated across the first resistor with high accuracy, for example with a tolerance less than or equal to 0.1%.

[0010] According to another possible characteristic, the second current generation module includes an operational amplifier, called the second operational amplifier, mounted in bilateral feedback (the operational amplifier comprising two feedback loops, one on each of the inputs of said operational amplifier), said operational amplifier having an inverting input, a non-inverting input and an output, the input of the second module being identified as a dipole whose terminals correspond to the output and the inverting input of said operational amplifier, the output and non-inverting input of said operational amplifier being connected respectively to the opposite terminals of said second resistor.

[0011] Advantageously, the second current generation module allows the input voltage of the second module to be duplicated across the second resistor with high precision, for example with a tolerance less than or equal to 0.1%.

[0012] According to another possible characteristic, the value of the offset voltage of the operational amplifier of the first module and / or the second module is very small compared to the voltage across the first resistor and / or the second resistor.

[0013] It is advantageous for the offset voltages of the various operational amplifiers of the device to be very small compared to the voltage(s) applied across the terminals of the first and / or second resistor, because these offset voltages could lead to very different current values ​​at the first and second resistors.

[0014] Note that by "very small" we mean that the value of the offset voltage of the operational amplifier of a current generation module is at least 1000 times smaller than the voltage across its associated resistor.

[0015] According to another possible characteristic, the input current value(s) of the operational amplifier of the first module and / or the second module are very small compared to the value of the first current and / or the value of the second current.

[0016] It is advantageous for the input current(s) of the operational amplifier of the first module and / or the second module to be very small compared to the currents generated across the first resistor and / or the second resistor, because these input currents can lead to very different current values ​​at the first and second resistors.

[0017] Note that by "very small" we mean that the value of the input current of the operational amplifier of a current generation module is at least 1000 times smaller than the value of the current flowing through its associated resistance.

[0018] According to another possible characteristic, the switched-capacitor link module is a four-terminal network comprising a first capacitor and a second capacitor which are mounted in parallel with each other via switches, called first and second switches, the input of the link module being identified with the terminals of the first capacitor and being connected to the output of the first module via switches, called third and fourth switches, the output of the link module, connected to the input of the second module, being identified with the terminals of the second capacitor.

[0019] The switched-capacitor link module is configured to advantageously duplicate the output voltage of the first module to the input of the second module as accurately as possible, in particular by limiting the injection or consumption of charges in the device according to the invention.

[0020] According to another possible characteristic, the first and second switches on the one hand, and the third and fourth switches on the other hand, are configured to switch in opposite phase.

[0021] Advantageously, there is charge transfer via the capacitors, as this is a component that allows lossless charge transfer between the first and second current generation modules.

[0022] According to another possible characteristic, the amount of charge injected by said switches of the link module is very small compared to the amount of charge stored by the first capacitor and / or by the second capacitor.

[0023] The switches, for example analog type switches, must be configured to alter the charge transfer between the first and second modules as little as possible, and thus allow the voltage across the first resistor to be duplicated as accurately as possible across the second resistor.

[0024] It should be noted that by "very small" we mean that the amount of charge injected by each of the switches of the link module is at least 1000 times smaller than the amount of charge stored by the first capacitor and / or by the second capacitor of the link module.

[0025] According to another possible characteristic, the device is configured so that the voltages across the first resistor, across the first capacitor, across the second capacitor, and across the second resistor are substantially equal. Thus, the voltage values ​​across the said capacitors are preferably as identical as possible with regard to the tolerance on the first and second currents, for example less than or equal to 0.1%.

[0026] According to another possible characteristic, the switched-capacitor link module has a switching frequency that is very small compared to the charging time of the capacitors in the switched-capacitor link module. Thus, the switching time of the switches is advantageously at least 10 times smaller than the charging time of said capacitors.

[0027] According to another possible characteristic, said device includes a voltage-to-current conversion module, said conversion module including an input and an output, an input voltage applied to the input of said conversion module generating, at the output of said module, the control current.

[0028] Advantageously, the value of the currents generated by the device according to the invention can be controlled by adjusting the input voltage of the voltage-current conversion module, facilitating the integration of the device into larger electronic assemblies or systems.

[0029] According to another possible characteristic, said voltage-to-current conversion module includes an operational amplifier, called a third operational amplifier, a transistor and at least two resistors.

[0030] The device according to the invention makes it possible to make the uncertainties on the values ​​of currents generated mainly dependent on the first and second resistors, thus limiting the need to have many electronic components with small tolerances, thereby lowering the cost of such a device and making the manufacture of such a device simpler.

[0031] According to another possible characteristic, the first resistance and the second resistance have resistance values ​​with a tolerance less than or equal to 0.5%, and preferably less than or equal to 0.1%.

[0032] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of a particular embodiment of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings, in which: - Fig. 1 illustrates a very schematic representation of a current generation device according to the invention; - Fig. 2 illustrates a schematic representation of a control module of the device in Fig. 1.

[0033] Fig. 1 thus illustrates a schematic representation of a device 1 for generating at least two electric currents h and I2, respectively first current and second current, from a control current I.

[0034] The said device 1 thus comprises at least: - a first current generation module 3 comprising at least one resistor Ri, referred to as the first resistor, said first module 3 being configured so that a voltage Vi applied across the terminals of the first resistor Ri generates the first current Ii, the voltage V applied across the terminals of the first resistor Ri being a function of the control current I c ; - a second current generation module 5 comprising at least one resistance R2, referred to as the second resistance, said second module 5 being configured so that a voltage V2 applied across the terminals of the second resistance R2 generates the second current I2; - a switching capacitive link module 7 which connects the first module 3 to the second module 5, said link module 7 being configured so that the voltage Vi applied across the first resistance Ri is applied across the second resistance R2 (thus by means of the link module, we have V2 which is substantially equal to V).

[0035] The first module 3 is a quadrupole which includes an input 3a and an output 3b, the linking module 7 is a quadrupole which includes an input 7a and an output 7b, the output 3b of the first module 3 being connected (or linked) to the input of the linking module 7. The second module 5 includes, for its part, an input 5a connected to the output 7b of the linking module 7.

[0036] The first current generation module 3 includes an operational amplifier AOi, called the first operational amplifier, mounted in bilateral feedback, that is to say that the operational amplifier AOi is mounted in positive feedback and in negative feedback.

[0037] The said first operational amplifier AOi has an inverting input, a non-inverting input and an output, the input 3a of the first module 3 being identified as a dipole whose terminals correspond to the output and the inverting input of the first operational amplifier AOi.

[0038] The said device 1 further advantageously comprises a control module 9 comprising at least one output 9a connected to the input 3a of said first module 3. Said control module comprising at least one control resistor R c The voltage applied across the terminals of said resistor R generates the control current I cThe output of the control module 9a is identified as a dipole whose terminals correspond to the terminals of the control resistor R c .

[0039] Output 3b of the first module 3, on the other hand, is identified as a dipole whose terminals correspond to the terminals of the first resistor R b the output and non-inverting input of said operational amplifier AOi being connected respectively to the opposite terminals of said first resistor R

[0040] It is advantageous that the offset voltages of the various operational amplifiers AOi and AO2 of device 1 be very small compared to the voltage(s) applied across the terminals of the first resistor Ri and / or the second resistor R2, because these offset voltages could lead to very different current values ​​at the first and second resistors Ri and R2.

[0041] The operational amplifier AO2 has an inverting input, a non-inverting input, and an output. Input 5a of the second module 5 is identified as a dipole whose terminals correspond to the output and the inverting input of the second operational amplifier AO2, and the output and the non-inverting input of the second operational amplifier A02 being connected respectively to the opposite terminals of said second resistor R2.

[0042] Furthermore, each of the operational amplifiers AOi and AO2 has its own offset voltage and input current, and these quantities (relative to said operational amplifiers) are respectively very small compared to the voltages across the first resistance Ri and / or the second resistance R2, and to the currents generated h and I2 across the first resistance Ri and / or the second resistance R2.

[0043] It should be noted that by "very small" we mean that the value of the offset voltage of the operational amplifier AOi or AO2 of a current generation module 3 or 5 is at least 1000 times smaller than the voltage Vj or V2 across its associated resistance Ri or R2, and preferably at least 10000 times smaller than the voltage across its associated resistance Ri or R2.

[0044] It should also be noted that by "very small" we mean that the value of the input current of the operational amplifier AOi or AO2 of a current generation module 3 or 5 is at least 1000 times smaller than the value of the current flowing through its associated resistance Ri or R2, and preferably at least 10000 times smaller than the value of the current flowing through its associated resistance Ri or R2.

[0045] The switching capacitance linking module 7 comprises a first capacitor Ci and a second capacitor C2 which are connected in parallel with each other via switches Si and S2, referred to respectively as the first and second switches, the input 7a of the linking module 7 being identified with the terminals of the first capacitor Ci and being connected to the output 3b of the first module 3 via switches S3 and S4, referred to respectively as the third and fourth switches,

[0046] Output 7b of link module 7, connected to input 5a of the second module 5, is thus identified with the terminals of the second capacitor C2. The aforementioned switches Si to S4 are, for example, analog type switches.

[0047] The S switches bS2, S3 and S4 are advantageously configured so that the quantity of charges injected by said switches Si, S2, S3 and S4 is very small compared to the quantity of charges stored by the first capacitor Ci and / or by the second capacitor C2.

[0048] It should be noted that by "very small" we mean that the quantity of charges injected by each of the switches Si at S4 of the linking module 7 is at least 1000 times smaller than the quantity of charges stored by the first capacitor Ci and / or by the second capacitor C2.

[0049] The third and fourth switches S3 and S4 are therefore arranged on the connections linking the output 3b of the first module 3 to the input 7a of the linking module 7, each of said connections including one of said switches S3 or S4. While the first and second switches Si and S2 are arranged on the connections linking the respective terminals of the first and second capacitors Ci and C2 to each other, each of said connections including one of said switches Si or S2.

[0050] The first and second switches Si and S2 on the one hand, and the third and fourth switches S3 and S4 on the other hand, are configured to switch in opposite phase and 0, that is to say that when the first and second switches Si and S2 are open, the third and fourth switches S3 and S4 are closed, and vice versa.

[0051] The opening and closing of switches Si to S4 is advantageously controlled by a control signal Sc , for example a square signal, generating a switching (in opposite phase) of said switches Si to S4 according to a switching frequency f .

[0052] Note that the switching frequency f c is very small compared to the charging time of the first and second capacitors Ci and C2, and / or that the switching time of the switches Si to S4 is advantageously at least 10 times smaller than the charging time of said capacitors Ci and C2.

[0053] Thus, when a control current I is applied to input 3a of the first module 3, there is a voltage V) across the first resistor Ri and a first current L which is generated by the first module 3, where via the first operational amplifier (op-amp)

[0054] As soon as the third and fourth switches S3 and S4 are closed, a voltage Vi is established across the terminals of the first capacitor C has it charges, then when the third and fourth switches S3 and S4 open and the first and second switches Si and S2 close, there is then a transfer of charge from the first capacitor Ci to the second capacitor C2, the voltage across the second capacitor C2 then corresponding to the voltage V).

[0055] Then, the first and second switches S1 and S2 open again, while the third and fourth switches S3 and S4 close under the effect of the control signal S c There is then a voltage V2 across the second resistor R2 and generation of a second current I2, where the voltage V2 corresponds approximately to the voltage Vi, thus

[0056] Of course, if the values ​​of the first and second resistances Ri and R2 are approximately equal, then the values ​​of the first and second currents L and I2 are also approximately equal. are substantially equal, i.e. currents b and I2 showing a very small difference between them, for example less than 0.5%.

[0057] It should be noted that the voltage Vi applied across the terminals of the first resistance Ri corresponds approximately to the value of the voltage across the terminals of the first capacitor Ci, then approximately across the terminals of the second capacitor C2, and finally approximately across the terminals of the second resistance R2.

[0058] Thus, due to the fact that: - the first and second amplifiers AOi and AO2 are configured to duplicate an input voltage into a voltage applied respectively across the terminals of the first and second resistors Ri and R2 with an uncertainty much lower than that expected on the first and second currents b and I2; - the switching capacitive link module 7 (in particular the switches Si to S4) is configured to duplicate the output voltage of the first module 3 to the input 5a of the second module 5 with a much lower uncertainty than expected on the first and second currents b and I2.

[0059] Thus, when the values ​​of the first and second resistances Ri and R2 are substantially the same, the values ​​of the first and second currents b and I2 have an identical value with a low uncertainty or tolerance, for example less than 0.5%.

[0060] When the values ​​of the first and second resistances Ri and R2 are different, for example with a ratio k, then b = k I2 with a low uncertainty or tolerance, for example less than 0.5%.

[0061] Figure 2 illustrates a very schematic representation of a control module 9, said module 9 being here a voltage-current conversion module. The said conversion module 9 comprises an input 9b and an output 9a, a voltage V E applied at the input of said conversion module 9 generating at the output of said module 9 the control current I c .

[0062] The voltage-to-current conversion module 9 comprises an operational amplifier AO3, referred to as the third operational amplifier, a transistor Ti, and at least two resistors: a control resistor R and a foot resistor R P (foot resistance can also be referred to as shunt resistance).

[0063] The third operational amplifier AO3 thus comprises a non-inverting input, an inverting input, and an output. The transistor T bFor example, a JFET (Junction Field Effect Transistor) transistor has a gate connected to the output of the third amplifier. operational AO3, a drain connected to one of the terminals of the control resistor R and a source connected to ground via the foot resistor R P .

[0064] Furthermore, the third operational amplifier AO3 is configured with negative feedback, the output of said third operational amplifier AO3 being connected to the inverting input of said amplifier AO3 via transistor T h The inverting input of the third operational amplifier AO3 is thus connected to the source of said transistor Ti and to one of the terminals of the foot resistor R P .

[0065] Thus, when an input voltage V Eis applied to the input of said conversion module 9, that is to say here at the non-inverting input of the third operational amplifier AO3, there is generation of the control current I through the control resistor R c (and a current I RP foot resistance R P , IRP and I c being equal).

[0066] Insofar as j > and with I R p = IC therefore T > , then R P R PCR P j _ RcV E - 12 ~ R P R2

[0067] The third operational amplifier AO3 is configured to operate in linear mode, thus a variation in the value of the input voltage V E allows the value of the control current I to be varied c , and therefore by extension the values ​​of the first and second currents L and I2 generated by device 1 according to the invention.

Claims

Demands

1. Device (1) for generating at least two electric currents from a control current (I c ), said device (1) comprising: - a first current generation module (3) comprising at least one resistance (Ri), referred to as the first resistance, said first module (3) being configured so that a voltage across the terminals of the first resistance (Ri) generates a first current (Ii), the voltage applied across the terminals of the first resistance (Ri) being a function of the control current (I); - a second current generation module (5) comprising at least one resistor (R2), referred to as the second resistor, said second module (5) being configured so that a voltage across the terminals of the second resistor (R2) generates a second current (I2); - a switching capacitor link module (7) which links the first module (3) to the second module (5), said link module (7) being configured so that the voltage applied across the terminals of the first resistor (Ri) is duplicated across the terminals of the second resistor (R2).

2. Device (1) according to the preceding claim, characterized in that the first current generation module (3) comprises an operational amplifier (AOi), referred to as the first operational amplifier, mounted in bilateral feedback, said operational amplifier (AOi) having an inverting input, a non-inverting input and an output, the input (3a) of the first module (3) being identified as a dipole whose terminals correspond to the output and the inverting input of said operational amplifier (AOi), the output (3b) of the first module (3) being identified as a dipole whose terminals correspond to the terminals of the first resistor (Ri), the output and the non-inverting input of said operational amplifier (AOi) being connected respectively to the opposite terminals of said first resistor (Ri).

3. Device (1) according to any one of the preceding claims, characterized in that the second current generation module (5) comprises an operational amplifier (AO2), referred to as the second operational amplifier, mounted in bilateral negative feedback, said operational amplifier (AO2) having an inverting input, a non-inverting input and an output, the input (5a) of the second module (5) being identified as a dipole whose terminals correspond to the output and the inverting input of said operational amplifier (AO2), the output and the non-inverting input of said operational amplifier (AO2) being connected respectively to the opposite terminals of said second resistor (R2).

4. Device (1) according to claim 2 or 3, characterized in that the value of the offset voltage of the operational amplifier (AO i, AO2) of the first module (3) and / or the second module (5) is very small compared to the voltage across the first resistor (Ri) and / or the second resistor (R2).

5. Device (1) according to any one of claims 2, 3 or 4, characterized in that the input current(s) of the operational amplifier (AOi, AO2) of the first module (3) and / or the second module (5) are very small compared to the value of the first current (b) and / or the value of the second current (I2).

6. Device (1) according to any one of the preceding claims, characterized in that the linking module (7) with switched capacitors is a four-terminal network comprising a first capacitor (Ci) and a second capacitor (Ci) which are connected in parallel with each other through switches (S1, S2), referred to as the first and second switches, the input (7a) of the linking module (7) being identified with the terminals of the first capacitor (Ci) and being connected to the output (3b) of the first module (3) through switches (S3, S4), referred to as the third and fourth switches, the output (7b) of the linking module (7), connected to the input (5a) of the second module (5), being identified with the terminals of the second capacitor (C2).

7. Device (1) according to claim 6, characterized in that the first and second switches (S bS2) on the one hand, and the third and fourth switches (S3, S4) on the other hand, are configured to switch in opposite phase.

8. Device (1) according to any one of claims 6 or 7, characterized in that the quantity of charge injected by said switches (S S4) of the linking module (7) is very small compared to the quantity of charge stored by the first capacitor (Ci) and / or by the second capacitor (C2).

9. Device (1) according to any one of claims 6 to 8, characterized in that the device (1) is configured so that the voltages across the first resistor (Ri), across the first capacitor (Ci), across the second capacitor (C2) and across the second resistor (R2) are substantially equal.

10. Device (1) according to any one of the preceding claims, characterized in that the switched-capacitor link module (7) has a switching frequency (f c ) very small compared to the charging time of the capacitors (Ci, C2) of the link module (7) with switched capacitors.

11. Device according to any one of the preceding claims, characterized in that the first resistance (Ri) and the second resistance (R2) have resistance values ​​with a tolerance less than or equal to 1%, and preferably less than or equal to 0.5%.

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