Generator for operating a surgical instrument

Abstract

The generator (11) suitable for pulse operation according to the invention includes a power factor correction circuit (21) with an integrated circuit (31). The voltage detector input (VSENSE) of the control circuit (31) is connected upstream to an amplifier (35). It is possible to configure the amplifier (35) such that its amplification factor has a value of 1 under a first condition and a value greater than 1 under a second condition. Furthermore, the amplification factor can be set to a value greater than 1 only when the voltage at the converter output is within the tolerance provided for the normal operation of the power factor correction circuit (21). Outside this tolerance range, the amplification factor of the amplifier (35) is then exactly 1. In doing so, especially during startup, the normal operation of the integrated control circuit (31) is not disturbed.

Description

Technical Field

[0001] The present invention relates to a generator for operating one or more surgical instruments, and in particular for supplying electrical power to such instruments. Background Technology

[0002] Electrosurgical instruments for use on human or animal patients are generally known from the prior art, as are generators used to supply such instruments. In this regard, EP 2 853 217 B1 discloses a generator to which a monopolar instrument and an associated neutral electrode are connected. For power supply, the generator can be connected to a public electrical grid.

[0003] The generator includes a grid rectifier at its input side, with a power factor correction circuit connected downstream of the grid rectifier. The latter is configured as a flyback converter and charges a storage capacitor to a peak voltage higher than the highest expected grid voltage. Thus, the storage capacitor has the task of storing the required energy to avoid excessive voltage drop, and, in the case of pulsating loads, at least a voltage drop below the grid peak voltage, so that no uncontrolled current flow occurs through the grid rectifier and flyback converter to the storage capacitor. A DC voltage converter is connected to the flyback converter, wherein the DC voltage converter has an inverter and a transformer to ensure reliable potential separation between the patient-side electrical equipment and the grid-side electrical system. The DC voltage converter also includes a controlled switch and a buffer capacitor. The power factor correction circuit and the DC voltage converter include controllers that communicate with each other via a data interface. Connected to the DC voltage converter is a radio frequency oscillator, which provides the radio frequency treatment voltage required to supply surgical instruments.

[0004] To implement a power factor correction circuit, an integrated circuit, such as the ICE3PCS01-DS from Infineon Technologies, can be used. Its features and applications are recommended at https: / / www.infineon.com / dgdl / Infineon-ICE3PCS01-DS-v03_00-EN.pdf The fileId=db3a304329a0f6ee0129a67ae8c02b46 is obvious.

[0005] Under varying load conditions, voltage fluctuations occur across the storage capacitors in the power factor correction circuit, necessitating a correspondingly large-scale design for the storage capacitors. This results in significant space requirements and susceptibility to errors due to the charging and discharging current stresses on the buffer capacitors or corresponding capacitor blocks. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a generator having a power factor correction circuit that includes reduced assembly space and improved reliability.

[0007] This objective is achieved by means of the generator according to claim 1: The generator according to the invention serves the operation of surgical instruments, meaning it is used to supply them with conventional radio frequency voltage and current, wherein the operation of the instrument can be pulsed. Pulses can be generated by the repeated switching of the instrument on and off for several seconds, as performed by the surgeon in the context of his / her surgery. Pulses can also arise from the fact that the selected mode of operation for the instrument requires continuous switching of the voltage of the RF generator. The pulses can be in the sub-hertz range or also in the range of one or several hertz. Higher frequency pulses are also possible.

[0008] As is common, the power factor correction circuit is based on a flyback converter circuit whose input is connected to a mains rectifier, and whose converter output is connected to at least one storage capacitor. The flyback converter also includes an electronic switch with a control electrode, such as a field-effect transistor with a gate electrode. To control the electronic switch, a control circuit is provided, whose switch signal output is connected to the control electrode (e.g., the gate of the field-effect transistor). The control circuit also includes a voltage detector input, which is connected to the converter output, for example, via a voltage tap circuit. In this way, the control circuit receives a signal at its voltage detector input characterizing the voltage present on the storage capacitor.

[0009] The control circuit is typically an integrated circuit configured for the operation of a power factor correction circuit, commercially manufactured and distributed in large quantities, and thus readily available on the market. However, such a circuit is typically unsuitable for power factor correction circuits that supply loads that change abruptly and dramatically, particularly slowly pulsating loads in the Hertz or sub-Hertz range, or that would require excessively large capacitor banks for this purpose. The present invention provides a remedy for this by arranging a signal amplifier between the voltage tap circuit and the voltage detector input of the control circuit. Thus, the control circuit becomes suitable for the operation of a power factor correction circuit capable of supplying loads that change dramatically, particularly pulsating loads, without internal interference.

[0010] The control circuit is preferably an integrated circuit, such as the ICE3PCS01G from Infineon Technologies, the L4985 from STMicroelectronics, the TEA2376DT from NXP, or the UCC28180 from Texas Instruments. Additional ICs from these or other manufacturers can also be used.

[0011] The circuit is designed and calibrated for its standard applications to operate with uniform or gradually changing loads. The circuit is also suitable for rapidly changing loads; however, in the case of rapid load changes, temporary voltage fluctuations at the converter output must be anticipated. Due to the additional amplifier provided according to the invention and connected upstream of the voltage detector input, the power factor correction circuit also becomes suitable for operation with rapidly changing loads, while avoiding large voltage fluctuations, enabling the generator to also use the power factor correction circuit to provide a pulsed operation mode. This is possible without the need to utilize enlarged storage capacitors (packets) to compensate for temporary voltage deviations.

[0012] The indicated control circuitry can have an overvoltage shutdown function configured to shut down the flyback converter if the voltage at the voltage detector input VSENSE exceeds a threshold. Additionally, the control circuitry can include another signal input OVP, which is connected to the converter output via a voltage divider circuit if necessary, to monitor the converter output for overvoltage. To prevent inconsistent signals from being supplied to the voltage detector input VSENSE and the additional signal input OVP during flyback converter startup after starting from an empty storage capacitor (meaning during the period when the storage capacitor is still uncharged), it is suitable to vary the amplifier's amplification factor during operation of the power factor correction circuitry. Doing so prevents the control circuitry from switching to an error mode and shutting down the power factor correction circuitry.

[0013] Specifically, the amplifier can include a control input configured for controlling the amplification factor. The amplification factor of the amplifier can be switched between at least two different values ​​via the control input. Preferably, the first value is equal to one, and the second value is greater than one. This concept is particularly suitable for ICs in which an amplified signal is not provided to the voltage detector input VSENSE. In such ICs, inconsistent signals could otherwise result in different inputs to the IC due to additional signal amplification. This could lead to difficulties, such as false shutdown, for example, during circuit startup, particularly during cold start.

[0014] In a preferred embodiment, the control circuit includes a signal output VB_OK, which indicates that the desired setpoint voltage is provided at the converter output of the power factor correction circuit. This signal output VB_OK is preferably connected to the switching input of the amplifier. This enables the power factor correction circuit to receive an unamplified signal at its voltage detector input after being turned on and thus control the flyback converter according to its specifications. If the setpoint voltage at the converter output is achieved, for example, 400 volts, the signal provided at the signal output VB_OK of the control circuit changes its value. This signal is supplied as a switching signal to the control input of the amplifier, whereby the latter now includes an amplification factor greater than one. In doing so, the loop amplification in the control loop formed by the amplifier and the control circuit increases, which now results in improved control accuracy once the setpoint voltage (e.g., 400 volts) has been reached. In doing so, it becomes possible to reduce the size of the capacitor or capacitor pack used to buffer load fluctuations at the converter output, which saves installation space and also allows for improved overall reliability of the generator due to reduced charging and discharging currents. On the other hand, interference with the operation of the IC, particularly during the startup phase, is avoided. Attached Figure Description

[0015] Further details and advantages of the invention will become apparent from the accompanying drawings, the description and associated figures, and the claims. In the drawings: Figure 1 A generator for operating surgical instruments, illustrated with its functional blocks, is shown. Figure 2 In addition to Figure 1 In addition to the generator's control circuit, the grid rectifier and power factor correction (PFC) circuit are also shown in the form of a basic circuit diagram. Figure 3 Shown in the form of a basic circuit diagram according to Figure 2 A controllable amplifier with a power factor correction circuit. Figure 4 Showing according to Figure 3 The circuit branch of the controllable amplifier, Figure 5 Shown as a basis Figure 2 The turn-on delay circuit is part of the power factor correction circuit, and Figure 6 A diagram showing the start-up operation of the pulse operation used in the illustrated power factor correction circuit is provided. Detailed Implementation

[0016] exist Figure 1The illustration depicts a medical device 10 for surgical or other effects on a patient, and a generator 11 serving the device 10. The device 10 is illustrated as a monopolar device, which must be attached to the patient. A neutral electrode 12 is dispensed onto the monopolar device. The neutral electrode 12 and the device 10 are connected to the generator 11 via electrical wiring. However, instead of a monopolar device, bipolar or multipolar devices can also be used, if applicable, which then eliminate the need for a neutral electrode.

[0017] Generator 11 is specially configured and suitable for operating the device in a mode where the electrical load provided by the device and thus the electrical power consumed by the device suddenly changes between very low and very high values. The low value can be a power value close to zero watts or only a few watts. The high value can be a power value ranging from hundreds of watts to kilowatts.

[0018] Generator 11 includes a radio frequency (RF) oscillator 13 configured to provide the required electrical power at output 14, with device 10 and neutral electrode 12 connected to output 14. Additionally, the RF oscillator 13 includes a control input 15 configured to receive control pulses that control the RF oscillator 13. For example, the control pulses can enable the RF oscillator to be turned on and off, or otherwise modulated. Figure 1 As an example of the timing of the control pulses, a square wave is illustrated within the block representing the radio frequency oscillator 13, according to which the RF oscillator 13 is turned on and off at defined time intervals. Thus, the interval between the on and off moments (which means between the leading and trailing edges of the square wave pulse) can be approximately 10 to approximately 100 milliseconds, or it can be one second or several seconds. In other words, the frequency of these control pulses can be in the sub-hertz or hertz range.

[0019] The system control unit 15 serves to generate control pulses and thus to define the operating modes of the entire generator 11 and, in particular, the radio frequency oscillator 13. The system control unit is connected to a communication unit 16, which is configured to receive user input and indicate outputs. For this purpose, the communication unit 16 includes input elements 17, for example, in the form of keys, buttons, or switches, and output units 18, for example, in the form of one or more screens and / or indicator devices and / or control lights.

[0020] The current supply unit 19, illustrated in the upper portion of generator 11, serves to supply current, specifically to the radio frequency oscillator 13, and also to the system control unit 15 and the communication unit 16. The current supply unit 19 is connected to a common power grid on its input side and supplies current to the components of generator 11 with necessary electrical reliability through potential isolation. This means that the current supply unit 19 is configured with potential isolation between the power grid side and the patient side, ensuring that the potential difference of several thousand volts between the power grid on one side and the patient or device 10 and neutral electrode on the other side does not result in harmful current flowing through the patient.

[0021] First, the input rectifier 20, which has a grid filter connected to the power grid, is part of the current supply unit 19. The input rectifier 20 is typically configured as a bridge rectifier and supplies a rippled DC voltage U at its output. r ripple DC voltage U r The voltage is supplied to the input of the power factor correction circuit 21. The power factor correction circuit 21 (PFC) converts this voltage into a DC voltage applied at its output, which is higher than the peak voltage of the mains voltage.

[0022] The power factor correction circuit 21 includes an output 22, in which a DC voltage, already converted by the power factor correction circuit 21, is provided. Output 22 is connected to input 23 of a potential-isolated voltage converter 24, the output 25 of which is in turn connected to an RF oscillator 13 to supply electrical power to it. The voltage converter 24 is configured in a potential-isolated manner, meaning that the input 23 and output 25 are currently separated. The dielectric strength of this current isolation is typically in the range above 6 kV, preferably 10 kV or 12 kV.

[0023] Optionally, a control connection, such as a data connection, can be provided between the system control unit 15 and the voltage converter 24. For example, this data connection can be used to set the amount of voltage output or other parameters at the output 25. Similarly, as an option, a control connection can be provided between the system control unit 15 and the power factor correction circuit 21, for example, to activate or deactivate the power factor correction circuit 21, such as to preset a standby mode.

[0024] The main focus of this invention is the configuration of the power factor correction circuit 21, which in Figure 2The circuit is represented in the form of a basic circuit diagram. The power factor correction circuit 21 includes a flyback converter circuit 26, the main components of which are an inductor 27, a diode 28 connected in series with it in the flow direction, an electronic switch 29 leading to ground from the point between them, and a storage capacitor CB connected to the diode and ground. The controllable switch 29 is preferably a field-effect transistor with its source connected to ground and its drain connected to the junction between the inductor 27 and the diode 28. Its control electrode 30 (or its gate in the case of a field-effect transistor) is connected to a control circuit 31 configured as an integrated circuit. A preferred component of the controlled circuit 31 is the ICE3PCS01G circuit from the manufacturer Infineon Technologies. Suitable additional integrated circuits available on the market that can be used here are such as the L4985 from STMicroelectronics, the TEA2376DT from NXP, and the UCC28180 from TXP, as well as many other integrated circuits.

[0025] The flyback converter circuit 26 largely corresponds to the standard circuit, and its specificities, except as described below, can be obtained from the datasheet of the control circuit 31. Figure 2 The connections to control circuit 31 and its external wiring, as well as connections that are not essential for understanding the circuit, are omitted. However, these connections are available and can be wired / connected as indicated in the datasheet.

[0026] Between the input rectifier 20 and the flyback converter circuit 26, a [missing information] is provided. Figure 5 The surge current limiting circuit 32 is illustrated separately. Essentially, the surge current limiting circuit 32 is a current limiting resistor R. When the corresponding connection VB_OK of the control circuit 21 is changed to a positive potential other than zero to turn on the connected transistor 34 and thereby close the contacts of the relay 33, the current limiting resistor R is short-circuited through the switching contacts of the relay 33. Once the voltage at the converter output 22 reaches the setpoint range, a positive voltage other than zero is applied to the connection VB_OK. In this case, based on the dimensions of the voltage tap circuit 40, the latter is between 380 and 410V for a desired converter output voltage U of 400V. The voltage tap circuit 40 is a voltage divider circuit with two or more ohmic resistors R1, R2.

[0027] Control circuitry 31 additionally includes an overvoltage protection input OVP, which is connected to converter output 22 via a voltage divider 41. The voltage divider is thus sized such that the shutdown limit at the overvoltage protection input OVP is only reached if an unacceptable overvoltage has been determined at converter output 22. For example, the latter is defined by the dielectric strength of the storage capacitor CB and can have a value of, for example, 420V.

[0028] Compared to the standard use of control circuit 31, the flyback converter circuit 26 is unique in that the amplifier is positioned between the voltage detector input VSENSE and the voltage tap circuit 40. Amplifier 35 includes a non-inverting input connected to the voltage tap A of the voltage tap circuit 40, which consists of resistors R1 and R2. The amplifier output is connected in the opposite direction to the voltage detector input VSENSE.

[0029] In a preferred embodiment, amplifier 35 additionally includes an inverting input connected to a reference voltage. The latter can be generated from the supply voltage VCC (e.g., 12V) at voltage standard, for example via a series resistor, in the form of a reference voltage source 36 (e.g., a Zener diode). Reference voltage source 36 is configured to provide a voltage also applied at voltage tap A if voltage U is at its setpoint value. In this case, the difference between the voltage at voltage tap A and the reference voltage is zero. Furthermore, if voltage U at output 22 is equal to its setpoint value, the reference voltage is equal to the voltage that must be applied to the input VSENSE of the control circuitry (specifically, the ICE3PCS01G from Infineon). If this voltage of reference voltage source 36 VSENSE is applied to input VSENSE, this voltage of reference voltage source 36 VSENSE neither causes an increase nor a decrease in voltage U. In this embodiment, a 2.5V reference voltage source, such as the ADR5041BKSZ from Analog Devices Inc., is used.

[0030] Amplifier 35 can be configured as an amplifier with a switchable amplification factor, such as... Figure 3As illustrated in the diagram, amplifier 35 can be an operational amplifier, with its non-inverting input connected to amplifier input EA via resistor R3. Its inverting input is connected to amplifier input EB via resistor R4, the value of which is equal to that of resistor R3. Resistor R5 is arranged in the feedback branch between the operational amplifier output and resistor R4, the ratio of R5 to R4 determining the amplification factor. A switch 37, particularly an electronic switch, can be provided in parallel with resistor R5, allowing resistor R5 to be short-circuited. A signal S can be used to control switch 37, specifically opening or closing it.

[0031] Figure 4 The diagram illustrates the implementation using a switch 37 of a field-effect transistor T, whose gate is connected to the control circuit 31 via a resistor, specifically to the connection VB_OK.

[0032] Under closed conditions (meaning current conduction switch 37), the amplification factor of amplifier 35 is "one". Conversely, if switch 37 is open (meaning current is blocked), the amplification factor is determined by the ratio of resistors R4 and R5 relative to each other. If the two resistors have equal values, the amplification factor is "two", as this is preferred in this case. However, other amplification factors are also possible.

[0033] The generator 11 described so far operates as follows: After the generator is switched on, the power factor correction circuit 21 must first charge the storage capacitor CB. For this purpose, the charging current can flow through the diode D, where the charging current is first limited by the surge current limiting circuit 32. The signal S connected to VB_OK is zero, thereby indicating that the voltage at the converter output 22 is still outside the setpoint voltage range. Since the switch 37 is closed under this condition, the amplifier 35 has an amplification of one. In other words, at the input VSENSE of the control circuit 31, the reference voltage of the reference voltage source 36 increases or decreases the difference between the voltage at voltage tap A and the reference voltage depending on the sign. Therefore, the flyback converter circuit 26 is connected to the... Figure 6 During the time period t0 indicated in the figure, the control circuit 31 operates in a manner that is jointly controlled by the control amplification rate set internally.

[0034] Once the voltage applied to the storage capacitor CB and thus also to the converter output 22 reaches the lower limit of the voltage tolerance range, the output VB_OK, indicating the setpoint voltage, changes to a positive value other than zero. Due to the appropriate size design of the voltage tap circuit 40 formed by the voltage divider or voltage divider 41 at the OVP connection, this limit can be appropriately limited to, for example, 380 volts.

[0035] Since signal S switches to a positive value when the preset switching threshold defined in this way is reached, on the one hand, the surge current limit 32 is deactivated due to the short circuit of resistor R, and on the other hand, switch 37 is opened. Therefore, the reference voltage now increases or decreases at voltage taps A and B. Figure 2 The voltage difference between the voltages at the input and output is doubled and provided to the voltage detector input VSENSE. Voltage feedback control (which is control circuit 31) and the control loop formed by the latter now operate with the increased amplification. Once and as long as the voltage U at the converter output is within a defined tolerance range, for example according to... Figure 6 This is the case between 380 and 410 volts. If the control circuit 31, formed by the integrated circuit, is designed as a proportional controller (P-controller), a proportional-integral controller (PI-controller), or a proportional-integral-derivative controller (PID-controller), then if (and preferably only if) the voltage U at output 22 is within a predetermined tolerance range, the proportional component P of the controller is increased at least by means of the present invention. This can be indicated by means of the signal at the output VB_OK of the integrated control circuit 31.

[0036] As the amplification of amplifier 35 increases, the desired setpoint voltage of 400 volts is now controlled in a feedback manner, where, for example, temporary deviations caused by sudden load changes are minimized by means of the increased amplification. This is achieved by following the switching on... Figure 6 The diagram illustrates a comparison of time phases t1, t2, and t3. In time phase t1, low current is consumed at converter output 22. After a transient voltage phase establishing up to the 400V setpoint voltage, the voltage remains constant. At the start of subsequent time phases t2, which can have durations of 100ms, 200ms, or even hundreds of milliseconds, high power, such as maximum power, is consumed at converter output 22. The transition between low and high power can be very rapid, for example, within a few milliseconds or a portion thereof. Consequently, the voltage drops during the short time phase so that it can subsequently be very quickly brought back to the 400V setpoint value. The noticeably low residual ripple is due to grid ripple, not to the control effect.

[0037] Due to the amplification of the signals obtained from voltage taps A and B, the voltage drop of U at output 22 is significantly lower than the voltage drop without such additional amplification and with a storage capacitor CB of the same size. Furthermore, the voltage increase after the end of load cycle t2 is significantly lower than the voltage increase without amplifier 35. Therefore, using the power factor correction circuit 21 described so far, it is possible to achieve a generator 11 whose RF oscillator 13 includes an operating cycle that changes very strongly and rapidly even between zero load and full load, without requiring the storage capacitor CB to be designed to be larger than usual. The capacitor CB can be sized only to meet the required residual ripple and the required full load values, without considering sudden load changes as considered herein.

[0038] As long as the signal connected to VB_OK is not zero, this means that amplifier 35 operates with an amplification factor greater than one as long as the voltage U at converter output 22 is within the desired tolerance range. Outside this tolerance range, amplifier 35 operates with an amplification factor equal to one, which means no amplification.

[0039] The generator 11, suitable for pulse operation according to the invention, includes a power factor correction circuit 21 having an integrated control circuit 32. The latter includes a feedback path, through which a control loop is formed. The power factor correction circuit 21 is configured to control a switch 29 by means of a switching pulse, such that voltage fluctuations at the voltage detector input VSENSE are canceled out.

[0040] Amplifier 35 is positioned in the feedback path provided for voltage control, wherein the amplifier includes an amplification factor greater than 1. For this purpose, the voltage detector input (VSENSE) of control circuit 31 is connected upstream to amplifier 35. In doing so, voltage fluctuations at converter output 22, which occur as a result of sudden load changes, can be minimized. It is possible to configure amplifier 35 such that its amplification factor has a value of 1 (or another unchangeable value) under a first condition and a value deviating from that value, preferably a larger value, under a second condition. Furthermore, the amplification factor can be set to a value greater than 1 only when the voltage at converter output is within the tolerance provided for the normal operation of power factor correction circuit 21. Outside this tolerance range, the amplification factor of amplifier 35 is then exactly 1. Thus, particularly during startup, the normal operation of integrated control circuit 31 is not disturbed.

[0041] List of reference numerals 10 Instruments 11 Generator 12 Neutral Electrodes 13 Radio Frequency Oscillator 14 Output 15 System Control Department 16 Communication Units 17 Input Elements 18 Indicator Components 19 Current supply unit 20 Input rectifier Ur is the voltage at the output of the input rectifier 20. 21 Power Factor Correction Circuit 22 Converter Output 23 Input of voltage converter 24 24 Voltage Converter 25 Output 26. Flyback converter circuit 27 Inductors 28 diodes 29 Controllable Switch / Transistor 30 Control Electrode 31 Control Circuit 32 Surge Current Limiting Circuit R Current limiting resistor 33 Relay VB_OK is used for the connection of the indicator for setting the point voltage. 34 transistors U converter output voltage OVP overvoltage protection input VSENSE voltage detector input 35 Amplifier 36 Reference Voltage Source VCC supply voltage 37 Switch T field-effect transistor 40 Voltage Tap Circuit 41. Voltage divider.

Claims

1. A generator (11) for operating surgical instruments (10), particularly for pulse operation, It has a power factor correction circuit (21), which includes a flyback converter circuit (26), the input of which is connected to a grid rectifier (20), and the converter output (22) of which is connected to at least one storage capacitor (CB), and includes an electronic switch (29) with a control electrode (30). It has a voltage tap circuit (40) connected to the converter output (22) and includes a voltage tap point (A). It has a control circuit (31) including a switch signal output (GATE) connected to the control electrode (30) and a voltage detector input (VSENSE) configured to receive a signal characterizing the voltage supplied on the storage capacitor (CB). It has an amplifier (35) which includes an amplifier input (EA) connected to the voltage tap point (A) and an amplifier output connected to the voltage detector input (VSENSE) of the control circuit (31).

2. The generator according to claim 1, characterized in that, The control circuit (31) is an integrated control circuit that includes an internally defined relationship between the signal at the voltage detector input (VSENSE) and the switching pulse output from it at the switch signal output (GATE).

3. The generator according to claim 2, characterized in that, The integrated circuit is designed for applications with non-pulse loads.

4. The generator according to any one of the preceding claims, characterized in that, The control circuit (31) includes a signal output (VB_OK) configured to output a signal indicating whether a voltage (U) that can be measured at the converter output (22) is within a defined tolerance range.

5. The generator according to any one of the preceding claims, characterized in that, The control circuit (31) includes a signal input (OVP) configured for detecting overvoltage at the converter output (22).

6. The generator according to claim 5, characterized in that, The control circuit (31) is configured to compare the voltage applied to the voltage detector input (VSENSE) with the signal input (OVP), and to turn off the flyback converter circuit (26) if the difference between these voltages exceeds a threshold.

7. The generator according to any one of the preceding claims, characterized in that, The amplifier (35) is a differential amplifier having an inverting input connected to a reference voltage source (36) and a non-inverting input connected to the voltage tap point (A).

8. The generator according to any one of the preceding claims, characterized in that, The amplifier (35) includes an input (S) configured to control the amplification rate.

9. The generator according to claim 8, characterized in that, The input (S) is a switch input configured to receive a switch signal to switch the amplification factor of the amplifier (35) between a first value and a second value.

10. The generator according to claim 8, characterized in that, The first value has a quantity equal to one, and the second value is greater than one.

Images