Switched capacitor for galvanically isolating and amplifying analog signals via transferred differential voltage signals

Abstract

An integrated circuit and method of providing an operational coupler including an input stage and an output stage between an analog input and an analog output; operating the plurality of high voltage domain switches of the input stage and the plurality of low voltage domain switches of the output stage synchronously at a frequency to galvanically isolate the input stage from the output stage across a plurality of capacitors having a plurality of input plates respectively connected to the switches of the input stage and the output stage; providing an analog input signal to the input stage; transferring a differential voltage signal component within the range of common mode voltage supply from the high voltage domain of the input stage to the low voltage domain of the output stage; differentially amplifying the low-voltage domain differential voltage signal component; and outputting the analog output signal.

Description

[0001] Priority

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 469,843, filed May 31, 2023, the contents of which are hereby incorporated in their entirety. TECHNICAL FIELD

[0003] The present disclosure relates to analog signal isolation and sensing, and in particular, to switched capacitors for current isolation and amplification of analog signals via transferred differential voltage signals. BACKGROUND

[0004] Many electrical measurements are made on systems that cannot be electrically connected to a measurement system via direct wiring. The devices used isolate the input signal from the output signal using any of several methods of making an electronic signal traverse an isolation barrier.

[0005] An isolated amplifier is an amplifier that is galvanically isolated between its input circuitry and output circuitry, including its associated power supply. Devices previously known as isolated amplifiers have complex companion isolation power supplies to provide power to the isolated side of the circuitry. Isolated amplifiers typically have independent, bulky, and expensive power supplies for their isolated input state. Some available devices integrate the input power supply with the amplifier into a single package. However, the power supply circuitry is complex and expensive due to the isolation across a digital barrier with modulation and demodulation complexity and an isolation power supply. These systems can convert the input analog signal to a digital signal and then convert the signal back to an analog signal via a transformer-powered analog-to-digital converter (ADC) and digital-to-analog converter (DAC). Alternatively, optical isolation products use optocouplers to directly couple analog signals so that they are not converted to digital signals. However, optical isolation products can not provide the desired offset, linearity, and drift characteristics.

[0006] There is a need for integrated circuits and methods for isolating an input analog signal from an output analog signal in an isolated amplifier of an electrical measurement system. SUMMARY

[0007] According to aspects, integrated circuits and methods are provided for switched capacitors for current isolation and amplification of analog signals via transferred differential voltage signal components. Isolated amplification can be provided for analog signals without analog-to-digital conversion of the signals and without an isolation power supply for the isolated side of the circuitry. The isolated amplifier can have an output stage with an integrated power supply.

[0008] Aspects provide a method comprising: providing an operating coupler comprising an input stage and an output stage between an analog input and an analog output; synchronously operating a plurality of high voltage domain switches of the input stage and a plurality of low voltage domain switches of the output stage at a frequency to galvanically isolate the input stage from the output stage across a plurality of capacitors having a plurality of input plates connected to the plurality of switches of the input stage and a plurality of output plates connected to the plurality of switches of the output stage, respectively; providing an analog input signal to the input stage; transferring a differential voltage signal component within a range of a common mode voltage supply from the high voltage domain of the input stage to the low voltage domain of the output stage; differentially amplifying the low voltage domain differential voltage signal component; and outputting an analog output signal.

[0009] According to an aspect, the method of the preceding paragraph is provided, wherein the frequency is greater than or equal to 100 MHz.

[0010] According to an aspect, the method of one of the two preceding paragraphs is provided, wherein the common mode voltage signal component is + / - 1000 volts.

[0011] According to an aspect, the method of one of the three preceding paragraphs is provided, wherein the common mode voltage signal component is + / - 100 volts, wherein the range of common mode voltage signal components is + / - 100 volts.

[0012] According to an aspect, the method of one of the four preceding paragraphs is provided, wherein the plurality of high voltage domain switches of the input stage and the plurality of low voltage domain switches of the output stage are synchronously operated such that a respective one of the plurality of switches is at the common mode voltage when off and at least three volts below the common mode voltage when on.

[0013] According to an aspect, the method of one of the five preceding paragraphs is provided, wherein the analog input signal comprises a voltage.

[0014] According to an aspect, the method of one of the six preceding paragraphs is provided, wherein the output signal is relative to a reference signal, wherein positive and negative output signals indicate a direction of current.

[0015] According to an aspect, there is provided a monolithic integrated circuit comprising: an input terminal for receiving an analog input signal; an operational coupler comprising: an input stage coupled to the input terminal and comprising a plurality of high voltage domain switches; an output stage comprising a plurality of low voltage domain switches and a voltage common mode supply; a galvanic isolation barrier between the input stage and the output stage comprising: a plurality of capacitors having a plurality of input plates respectively connected to the plurality of high voltage domain switches and a plurality of output plates respectively connected to the plurality of low voltage domain switches; and a controller for synchronously operating the plurality of input switches and the plurality of output switches at a frequency to charge respective ones of the plurality of capacitors to a voltage; wherein the operational coupler is for transferring a differential voltage signal component from a high voltage domain to a low voltage domain; a differential amplification circuit coupled to the output stage of the operational coupler; and an output terminal coupled to the differential amplification circuit to output an analog output signal.

[0016] According to an aspect, there is provided the monolithic integrated circuit of the preceding paragraph, wherein the controller is for synchronously operating the plurality of high voltage domain switches of the input stage and the plurality of low voltage domain switches of the output stage such that respective ones of the plurality of switches are at the common mode voltage when open and at least three volts below the common mode voltage when closed.

[0017] According to an aspect, there is provided a monolithic integrated circuit comprising: an input terminal for receiving an analog input signal; an operational coupler comprising: an input stage coupled to the input terminal and comprising a plurality of high voltage domain switches; an output stage comprising a plurality of low voltage domain switches and a voltage common mode supply; a galvanic isolation barrier between the input stage and the output stage comprising: a plurality of capacitors having a plurality of input plates respectively connected to the plurality of high voltage domain switches and a plurality of output plates respectively connected to the plurality of low voltage domain switches; and a controller for synchronously operating the plurality of input switches and the plurality of output switches at a frequency to galvanically isolate the input stage from the output stage and to transfer a differential voltage signal component within a range of common mode voltage supply from the high voltage domain to the low voltage domain; a differential amplification circuit coupled to the output stage of the operational coupler; and an output terminal coupled to the differential amplification circuit to output an analog output signal.

[0018] According to an aspect, there is provided the monolithic integrated circuit of the preceding paragraph, wherein the frequency is greater than or equal to 100 MHz.

[0019] According to one aspect, there is provided the monolithic integrated circuit of one of the two preceding paragraphs, wherein the common mode voltage signal component is + / - 1000 volts.

[0020] According to one aspect, there is provided the monolithic integrated circuit of one of the three preceding paragraphs, wherein the common mode voltage signal component is + / - 100 volts, wherein the range of the common mode voltage signal component is + / - 100 volts.

[0021] According to one aspect, there is provided the monolithic integrated circuit of the preceding paragraph, wherein the controller for synchronously operating the plurality of high voltage domain switches and the plurality of low voltage domain switches comprises a respective one of the switches that is at least three volts below the common mode voltage when open and at the common mode voltage when closed.

[0022] According to one aspect, there is provided the monolithic integrated circuit of one of the five preceding paragraphs, wherein the output signal is relative to a reference signal, wherein the positive output signal and the negative output signal indicate a direction of current. BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings illustrate examples of methods and integrated circuits for current isolation and amplification of an analog signal via a transferred differential voltage signal component. The methods and integrated circuits can be used for isolated amplification of an analog signal without analog-to-digital conversion of the signal and without an isolated power supply being provided to the isolated side of the circuit.

[0024] Figure 1 is a schematic diagram of an apparatus 100 depicting a differential voltage signal component for amplifying a voltage across a resistor.

[0025] Figure 2 is a schematic diagram of an operating coupler.

[0026] Figure 3 is a schematic diagram depicting a differential amplification circuit.

[0027] Figure 4 is a schematic diagram of an isolated amplifier circuit having an operating coupler with an input stage and an output stage and a differential amplification circuit.

[0028] Figure 5 is a schematic diagram of Figure 4 is a zoomed view of the operating coupler with the input stage and the output stage shown.

[0029] Figure 6 is a schematic diagram of a high voltage level shifter.

[0030] Figures 7A to 7F is a schematic diagram of Figure 6 is a schematic diagram of the high voltage level shifter shown, wherein the generated clock signal drives the input switches with their relative common mode.

[0031] Figure 8 A graph is shown indicating a switch capacitor providing an isolated voltage over time, where a differential voltage is transferred to a low voltage domain (while still maintaining a differential value).

[0032] Figure 9 A flowchart is shown of a method for current isolation and amplification of an analog signal via a switched capacitor with a transferred differential voltage signal component.

[0033] Reference designators appearing in more than one figure have the same meaning throughout the several figures and the mention or discussion of any illustrated element in the context of any particular figure also applies to each other figure in which that same illustrated element is shown, if any. DETAILED DESCRIPTION

[0034] According to one aspect, a circuit for isolated analog sensing is provided, where no additional power supply is provided on the isolated side of the circuit. The circuit can have a switched capacitor input to provide current isolation of an analog signal without requiring an isolated power supply to be provided to the isolated side of the circuit. The circuit, which can be provided as an integrated circuit, can provide accurate and economical shunt current sensing for high voltage systems (e.g., isolation up to + / - 1000 volts). The integrated circuit can be a monolithic current isolated amplifier with + / - 1000 volt common mode capability (CMC) that is applied to current sensing and industrial sensing. A monolithic integrated circuit is a complete circuit or group of circuits fabricated in a single piece of silicon. The monolithic current isolated amplifier can be self-contained in that no power supply is provided to the isolated side of the circuit. The current isolation can provide a DC isolation barrier while conveying a desired signal across the barrier, providing an open circuit for direct current (DC) and a low impedance path for alternating current (AC), with a level shift for the signal provided by a passive element (a capacitor). The input terminal can not have a direct electrical connection to the output terminal. In particular, the monolithic current isolated amplifier can have an input terminal that is not directly electrically connected to the output terminal, where a signal can be transferred from the input terminal to the output terminal by a switched capacitor. While this can be considered an indirect connection through a passive device (such as a capacitor), the output terminal is isolated from the input terminal when a differential voltage signal component is transferred from the input terminal to the output terminal.

[0035] The circuit achieves isolation through an isolation barrier that naturally occurs in a capacitor on a monolithic integrated circuit.

[0036] U.S. Patent Application Publication No. 2022 / 0376666, published November 24, 2022, is incorporated by reference herein in its entirety and for all purposes.

[0037] Figure 1is a schematic diagram of an apparatus 100 that depicts a differential voltage signal component of a voltage across a resistor. The amplified differential voltage signal component can be used in a differential current sense topology.

[0038] The apparatus 100 includes a resistor 102, a differential amplification circuit 104, and an operational coupler 106. The differential amplification circuit 104 and the resistor 102 are coupled to amplify a differential voltage signal component 108 of a voltage (voltage AV) across the resistor 102. The voltage across the resistor 102 is a difference between a voltage (voltage VI) at a first end of the resistor 102 and a voltage (voltage V2) at a second end of the resistor 102. The voltages VI and V2 can each include a common mode voltage signal component 112, e.g., a common mode voltage (VCM).

[0039] The operational coupler 106 is between the resistor 102 and the differential amplification circuit 104 to pass the differential voltage signal component 108 and isolate the common mode voltage signal component 112 of the voltage AV across the resistor 102. More specifically, the operational coupler 106 operates to provide VI - VCM to a first input terminal of the differential amplification circuit 104 and V2 - VCM to a second input terminal of the differential amplification circuit 104. Optionally, the operational coupler 106 can operate to provide a controlled common mode voltage (VCCM) along with the voltages V2 - VCM and VI - VCM to the first and second input terminals of the differential amplification circuit 104, as described below.

[0040] In one or more examples, the operational coupler 106 operates to pass the differential voltage signal component 108 and isolate the common mode voltage signal component 112 of the voltage AV via a plurality of integration and transfer stages performed at least partially in response to a control signal (control signal not depicted). The differential amplification circuit 104 amplifies the differential voltage signal component 108 to generate an amplified differential voltage signal component 110.

[0041] Figure 2 is a schematic diagram of an operational coupler 200 according to one or more examples. The operational coupler 200 is Figure 1 a non-limiting example of the operational coupler 106 of

[0042] Capacitors can be used to pass charge because they are passive devices and thus do not operate with a constant current. Further, the operational coupler 200 does not use current to bias the circuit. Thus, the dq / dt (change in charge / change in time) via the operational coupler 200 can be less than typical amplifier inputs and topologies.

[0043] The operational coupler 200 can include a first pair of capacitors 204, a second pair of capacitors 206, a controlled common mode voltage source 208, a first switch 214, a second switch 216, and a controller 250. For ease of illustration and discussion, Figure 2 An optional resistor 202 is depicted, the outline of which is depicted using dashed lines. The operational coupler 200 has an input stage 220 isolated from an output stage 230 by the first pair of capacitors 204 and the second pair of capacitors 206. The first pair of capacitors 204 and the second pair of capacitors 206 can provide a galvanic isolation barrier. The input stage 220 includes the second switch 216, which is a high voltage domain switch. The output stage 230 includes the first switch 214, which is a low voltage domain switch.

[0044] The first pair of capacitors 204 is switchably coupled between a negative input terminal of a differential amplification circuit, which can also be referred to herein as a "first input terminal," and the resistor 202. The second pair of capacitors 206 is switchably coupled between a positive input terminal of the differential amplification circuit, which can also be referred to herein as a "second input terminal," and the resistor 202.

[0045] A respective first switch of the first switch 214 is used to couple a respective bottom plate of the first pair of capacitors 204 and the second pair of capacitors 206 at the node 218 to either the negative input terminal of the differential amplification circuit or a positive output terminal of the controlled common mode voltage source 208. A return terminal of the common mode voltage source 208 is coupled to a common potential, illustrated as ground, but not limited thereto. A respective second switch 216 is used to couple a respective top plate of the first pair of capacitors 204 and the second pair of capacitors 206 to either the first terminal 210 of the resistor 202 or the second terminal 212 of the resistor 202. Examples of switches include, but are not limited to, silicon carbide (SiC) devices and insulated gate bipolar transistor (IGBT) devices.

[0046] The controlled common mode voltage source 208 provides a controlled common mode voltage (VCCM) to the node 218. The node 218 is switchably coupled to a respective bottom plate of the first pair of capacitors 204 and the second pair of capacitors 206 via a respective first switch 214. When one or more of the first pair of capacitors 204 and the second pair of capacitors 206 are in an integration phase, they integrate the voltage VCCM along with a differential voltage signal component, and transfer the differential voltage signal component along with VCCM during a transfer phase, as further described below. Any voltage source that reliably provides a controlled voltage level can be used as the controlled common mode voltage source 208.

[0047] The controller 250 can control the switches 214 and 216, the node 218, and the common mode voltage source 208.

[0048] The first switch 214 and the second switch 216 receive and operate in response to control signals (control signals not depicted) from the controller 250 that selectively turn on or turn off respective ones of the first switch 214 and the second switch 216. When respective ones of the first switch 214 and the second switch 216 are turned on, they divert current; when they are turned off, they do not divert current or divert negligible current.

[0049] When the first switch 214 and the second switch 216 are alternately turned on and turned off in a particular manner, respective ones of the first pair of capacitors 204 and the second pair of capacitors 206 alternately integrate and divert in a complementary and commutative manner. When the first pair of capacitors 204 and the second pair of capacitors 206 alternately integrate and divert at a sufficiently high frequency (e.g., but not limited to, substantially 100 megahertz (MHz) or higher), the output signal is generated and continuously applied to the positive input terminal and the negative input terminal of the differential amplification circuit, i.e., the output signal operating the coupler 200 remains faithful to the positive input terminal and the negative input terminal of the differential amplification circuit.

[0050] Referring again to Figure 1 , the amplitude of the output signal operating the coupler 106 is generally proportional to the voltage level of the differential voltage signal component. In one example, the amplitude of the output signal 108 operating the coupler 106 can be twice the amplitude of the voltage level across the resistor 102. Referring to Figure 2 , the first pair of capacitors 204 and the second pair of capacitors 206 can alternately integrate and divert at a sufficiently high frequency to charge a set of capacitors and also high enough to transfer the alternating set of charges to the input. When the first switch 214 and the second switch 216 operate at a higher frequency, fidelity can be improved such that the first pair of capacitors 204 and the second pair of capacitors 206 alternate at such a higher frequency.

[0051] In one or more examples, in response to the operation of the first pair of capacitors 204 and the second pair of capacitors 206 in a particular manner, the operating coupler 200 operates as an alternating current (AC) voltage short and a direct current (DC) voltage isolator. The common mode voltage is a DC voltage and (in the absence of external influences) does not change (or changes negligibly) and no AC common mode voltage is stored across the capacitors, thus the common mode voltage is not diverted as input voltage, providing DC voltage isolation.

[0052] Figure 3 is a diagram depicting a differential amplification circuit 300 in accordance with one or more examples. The differential amplification circuit 300 is a non-limiting example of the differential amplification circuit 104 of Figure 1 .

[0053] The differential amplification circuit 300 includes a first differential amplifier 302, a second differential amplifier 304, and a third differential amplifier 306. The respective positive input terminals of the first differential amplifier 302 and the second differential amplifier 304 can be coupled to the respective first (positive) input terminal and second (negative) input terminal of the operational coupler 106 or the operational coupler 200 (see Figure 2 ). The respective negative input terminals of the first differential amplifier 302 and the second differential amplifier 304 are coupled to internal nodes of respective resistive voltage divider circuits (including resistors R6 / R7 for the first differential amplifier 302 and resistors R8 / R9 for the second differential amplifier 304) coupled between ground or other common potential and respective outputs of the first differential amplifier 302 and the second differential amplifier 304. Utilization of resistive voltage divider circuits is optional to divide the gain and improve the speed of the first differential amplifier 302 and the second differential amplifier 304. The output of the first differential amplifier 302 is coupled via resistor R2 to the positive input terminal of the third differential amplifier 306, and the output of the second differential amplifier 304 is coupled via resistor R3 to the negative input terminal of the third differential amplifier 306. The positive input terminal of the third differential amplifier 306 is also coupled via resistor R4 to provide a pedestal voltage. This pedestal voltage can be used to set the output voltage from which the positive differential signal swing or the negative differential signal swing is referenced (above or below). The negative input terminal of the third differential amplifier 306 is also coupled via resistor R5 to an output terminal of the differential amplification circuit 300, which is coupled to the output of the third differential amplifier 306. The number of resistors utilized in the differential amplification circuit 300 is exemplary and does not limit the scope of the present disclosure in any way.

[0054] Figure 4 A circuit diagram is shown for an isolated amplifier circuit 400 for a monolithic integrated circuit. The isolated amplifier circuit 400 includes an operational coupler 410 and a differential amplification circuit 440. The operational coupler 410 has an input stage 420 isolated from an output stage 430 by a capacitor. The isolated amplifier circuit 400 can be used for current sensing, where a small input signal produces a high gain. The isolated amplifier circuit 400 can also be used as an isolated amplifier, where a large input signal produces a low gain.

[0055] The isolated amplifier circuit 400 has input terminals at node 1 and node 2 for input analog signals. The analog signals can be provided by Vsupply and LOAD connected through resistor Rl, where node 1 is between Vsupply and a first terminal of resistor Rl, and node 2 is between a second terminal of resistor Rl and LOAD.

[0056] The isolated amplifier circuit 400 can use the pedestal voltage PEDESTAL as a reference with respect to which the positive differential signal swing or the negative differential signal swing is set, from which the output voltage VOUT is set. The differential amplification circuit 440 can have three differential amplifiers 442, 444, and 446. The respective positive input terminals of the first differential amplifier 442 and the second differential amplifier 444 can be coupled to the respective first (positive) output terminal and second (negative) output terminal of the operational coupler 410 at nodes 3 and 4, respectively. The respective negative input terminals of the first differential amplifier 442 and the second differential amplifier 444 are coupled to an internal node of a respective resistive voltage divider circuit (comprising resistors R6 / R7 for the first differential amplifier 442 and resistors R8 / R7 for the second differential amplifier 444, where the resistor R7 is shared between the first differential amplifier 442 and the second differential amplifier 444). The output of the first differential amplifier 442 is coupled to the positive input terminal of the third differential amplifier 446 via a resistor R2, and the output of the second differential amplifier 444 is coupled to the negative input terminal of the third differential amplifier 446 via a resistor R3. The positive input terminal of the third differential amplifier 446 is also coupled to the pedestal voltage via a resistor R4.

[0057] Figure 4 The illustrated isolated amplifier circuit 400 senses current represented by the voltage drop across the resistor Rl as it travels between Vsupply and LOAD. The voltage common mode (VCM) is the voltage of Vsupply that can satisfy the load, and the amount of current flowing through the resistor Rl can be detected by the voltage drop across the resistor Rl, which can be small with respect to the voltage of Vsupply.

[0058] Whether the current is flowing from Vsupply to LOAD or from LOAD to Vsupply can be detected by whether the VOUT voltage is higher or lower than the PEDESTAL voltage. If the voltage between node 3 of the first differential amplifier 442 and node 4 of the second differential amplifier 444 is a differential negative value (node 3 - node 4 = negative voltage), then the voltage VOUT will be higher than the PEDESTAL voltage. Likewise, if the difference between node 3 of the first differential amplifier 442 and node 4 of the second differential amplifier 444 is positive (node 3 - node 4 = positive voltage), then the voltage VOUT will be lower than the PEDESTAL voltage. The isolation amplifier circuit 400 is bidirectional. The isolation amplifier circuit 400 detects whether the voltage VOUT is higher or lower than the reference voltage (called PEDESTAL) by obtaining a positive and negative difference on these nodes (node 3 - node 4) when the input signal (current) is flowing in both directions, respectively. The isolation amplifier circuit 400 provides this bidirectional detection by the nature of the amplifier setup. If the VOUT voltage is higher than the PEDESTAL voltage, then the current is determined to be flowing from Vsupply to LOAD. If the VOUT voltage is lower than the PEDESTAL voltage, then the current is determined to be flowing from LOAD to Vsupply.

[0059] Figure 4 The operation of the coupler 410 is shown with an input stage 420 isolated from an output stage 430 by a capacitor. The input stage 420 can have an integrated power supply through a high voltage capacitor via a common mode voltage source VCM 408 to provide a high voltage isolated input. There can be no data or power conversion. The isolation can be inherent, which reduces production costs, provides a smaller solution and operates more efficiently. The input stage 420 can be a set of high voltage domain switches. The output stage 430 can be a set of low voltage domain switches. The circuit assumes that a power supply has been provided to drive the differential amplifiers 442, 444, 446, and that same power supply for the differential amplifiers 442, 444, 446 can be used to produce a VCM reference voltage via the common mode voltage source 408. Vsupply can not be used to drive the circuit or power the circuit to communicate signals, but only to provide a passive power supply across node 1 and node 2 to the load. There is no actual power from the common mode voltage source 408 other than to compensate for (extremely small) signal power lost or gained every other cycle. The common mode voltage source 408 is used to set a reference value to which the signal climbs above or falls below every other cycle according to the input differential signal at node 1 and node 2.

[0060] The controller 450 can control the high voltage domain switches of the input stage 420, the low voltage domain switches of the output stage 430, and set the level of the common mode voltage source 408. The high voltage capacitor can be implemented as a level shifter to isolate the control signals of the high voltage domain switches of the input stage 420 from the control signals of the low voltage domain switches of the output stage 430.

[0061] Figure 5 An enlarged view of the operational coupler 410 is shown. Figure 4 The operational coupler 410 has four capacitors 412, 414, 416, and 418, an input stage 420 with a set of high voltage domain switches, and an output stage 430 with a set of low voltage domain switches. The switches of the input stage 420 and the output stage 430 can be two different voltage domains and can operate in sync and at a set frequency (e.g., 100 megahertz (MHz) or higher, but not limited to). In some aspects, the switches can operate at a lower sampling frequency, for example, for reduced offset (using longer charge times, larger capacitances). If only one type of transmission gate is used for the switches, e.g., PMOS, it can be simplified, but they can be different. The switches of the input stage 420 can reach the Vsupply voltage (off) and the Vsupply voltage (on). The high voltage domain switches of the input stage 420 and the low voltage domain switches of the output stage 430 can operate in sync so that the switches are the same as the common mode voltage source 408 when off and at least three volts lower than the common mode voltage source 408 when on. The voltage gate source (VSG) of a positive channel metal oxide semiconductor (PMOS) device can be Vsupply = off and Vsupply - 3V = on. In other words, the switches are in the off state, and the switches are in the on state.

[0062] Figure 5The input stage 420 is shown to include high voltage domain switches 422H, 422S, 424S, 424H, 426S, 426H, 428H, and 428S. The output stage 430 includes low voltage domain switches 432S, 432H, 434H, 434S, 436H, 436S, 438S, and 438H. The first terminals of the high voltage domain switches 422H, 424S, 426S, and 428H are connected in parallel to node 1. The first terminals of the high voltage domain switches 422S, 424H, 426H, and 428S are connected in parallel to node 2. The first terminals of the low voltage domain switches 432S, 434H, 436H, and 438S are connected in parallel to the positive output of the common mode voltage source 408, i.e., voltage VCM. The first terminals of the low voltage domain switches 432H and 434S are connected in parallel to node 3. The first terminals of the low voltage domain switches 436S and 438H are connected in parallel to node 4. The second terminals of the high voltage domain switches 422H and 422S are connected to the first plate of the capacitor 412, and the second terminals of the low voltage domain switches 432S and 432H are connected to the second plate of the capacitor 412. The second terminals of the high voltage domain switches 424S and 424H are connected to the first plate of the capacitor 414, and the second terminals of the low voltage domain switches 434H and 434S are connected to the second plate of the capacitor 414. The second terminals of the high voltage domain switches 426S and 426H are connected to the first plate of the capacitor 416, and the second terminals of the low voltage domain switches 436H and 436S are connected to the second plate of the capacitor 416. The second terminals of the high voltage domain switches 428H and 428S are connected to the first plate of the capacitor 418, and the second terminals of the low voltage domain switches 438S and 438H are connected to the second plate of the capacitor 418.

[0063] The isolation provided by the operational coupler 410 can be current through the capacitors 412, 414, 416, and 418. The topology of the operational coupler 410 can transfer differential voltage signal components hovering in the range of the common mode voltage source 408 to the low voltage domain, where the transfer can be done via capacitor coupling. For example, + / - 1000V signal components can be transferred down to + / - 500V, or + / - 100V, or any voltage less than + / - 1000V, but not limited to. The low voltage domain switches 432S, 432H, 434H, 434S, 436H, 436S, 438S, and 438H can be controlled, and the amplifier input side of the capacitors can be driven by a low voltage inverter to pump or pull voltage to drive the input gate. The capacitors for level shifting (see Figure 6) can be charged by a low voltage inverter (not shown) that pumps or pulls voltage to drive the high voltage domain switches 422S, 422H, 424H, 424S, 426H, 426S, 428S, and 428H. Specifically, the input switches at 422H, 422S, 424S, 424H, 426S, 426H, 428H, and 428S are low voltage switches that are at a high voltage. Also, the output switches 432H, 432S, 434S, 434H, 436S, 436H, 438H, and 438S are low voltage switches that are at a low voltage and are isolated by the 412, 414, 416, 418 HV capacitors.

[0064] The high voltage capacitors provide a current isolation function. The isolation can be implemented in the analog signal path without the need for an analog to digital conversion on the input side of the isolation circuit or a complementary digital to analog conversion on the output side of the isolation circuit. Since no isolation power supply is provided, a transformer can not be needed as part of the circuit. However, in the prior circuit, an isolation power supply was provided and thus a transformer was part of the prior circuit. With the high voltage capacitors for isolation in the analog signal path, the signal can remain analog from input to output.

[0065] Referring to Figure 6 , a schematic diagram of a high voltage level shifter 600 with minimal signal propagation time delay is depicted. The switches in the input stage 420 and the output stage 430 can be in two different voltage domains and can be synchronized by operating at a certain frequency, for example 100 MHz (see Figure 5 ). The high voltage domain switches 422H, 422S, 424S, 424H, 426S, 426H, 428H, and 428S of the input stage 420 can reach Vsupply voltage (off) and Vsupply-3V (on). Figure 6 The high voltage level shifter shown can provide fast isolation, charge pumping level shifting to allow the switches of the input stage 420 to reach (off) and (on). The level shifting can be by pumping the value to a common mode CM 602 or (CM-3V) (3 VGS clamp) via capacitors 606A and 606B. According to one aspect, a type of pass gate (PMOS) can be used, for example the transistors 604A-604H can be PMOS transistors.

[0066] Referring to Figures 7A to 7F , a schematic block diagram of the high voltage level shifter shown is depicted, where the generated clock signals drive the input switches with their relative common mode. Figure 6 Figure 7A is shown for a 60V common mode, S in is 57V and H in is 0V and S is 5V. Figure 7B ​shows 60V common mode, S in is 60V and H in is 57V provides H is 5V and S is 0V. Figure 7C shows 0V common mode, S in is -3V and H in is 0V provides H is 0V and S is 5V. Figure 7D shows 0V common mode, S in is 0V and H in is -3V provides H is 5V and S is 0V. Figure 7E shows -60V common mode, S in is -63V and H in is -60V provides H is 0V and S is 5V. Figure 7F shows -60V common mode, S in is -60V and H in is -63V provides H is 5V and S is 0V.

[0067] Figure 8 shows a graph of input voltage and output voltage over time, which illustrates the waveforms of control signals used to drive the switches of the operational coupler. The graph indicates that the high voltage capacitor provides isolation; the capacitors provide near-instantaneous voltage transfer (they only transfer the differential voltage signal component); and the capacitors provide negative and positive transfer (i.e., the transfer is bidirectional - the isolated amplifier circuit detects whether the voltage output is higher or lower than the reference common mode voltage (VCM)). Figure 8 shows two common mode examples, one at 60V and the other at 0V. Waveform 802 is a constant 0V to 5V clock. Waveform 804 is the result of a level shift, showing the generated clock signal to drive the input switch at its relative common mode. At 60V common mode, the switch on will be 57V and the switch off will be 60V. At 0V common mode, the switch on will be -3V and the switch off will be 0V.

[0068] The size of a monolithic integrated circuit can be smaller because there can be fewer external components and less board area taken up. The device can have lower power loss in shunt, where shunt can create a voltage drop when current flows to a load. The device can have lower IC power and can include a power save shutdown pin. The device can be more accurate and can be produced at less cost than isolated amplifiers that provide power to the isolated side of a circuit, convert analog signals to digital signals, or directly couple analog signals using optocouplers. The device can provide high voltage shunt current sensing, such as + / - 1000 volts, including bipolar common mode voltage (CMV). The device can provide sensing that is galvanically isolated from the measurement device current. The device can break the ground loop. The device can be implemented in high voltage systems including electric vehicles and solar panel arrays. The device can be used in industrial test and measurement where isolated sensing is often a design parameter.

[0069] Figure 9 A flowchart of a method for switching capacitors via a transferred differential voltage signal component to galvanically isolate and amplify an analog signal is shown. The method can provide isolated amplification of an analog signal without analog-to-digital conversion of the signal and without an isolated power supply being provided to a remote side of a circuit or input stage. An isolator is provided 902 that includes an input stage and an output stage between an analog input and an analog output. A plurality of high voltage domain switches of the input stage and a plurality of low voltage domain switches of the output stage are operated 904 synchronously at a frequency to galvanically isolate the input stage from the output stage across a plurality of capacitors having a plurality of input plates connected to the plurality of switches of the input stage and a plurality of output plates connected to the plurality of switches of the output stage, respectively. An analog input signal is provided 906 to the input stage. A differential voltage signal component within a range of a common mode voltage signal component (e.g., + / - 1000 V) is transferred 908 from the high voltage domain of the input stage to the low voltage domain of the output stage. The low voltage domain differential voltage signal component is differentially amplified 910. An analog output signal is output 912.

[0070] While examples have been described above, other variations and examples can exist according to the disclosure without departing from the spirit and scope of the disclosed examples.

Claims

1. A method, the method comprising: An operation coupler is provided, the operation coupler comprising an input stage and an output stage between analog inputs and analog outputs; Multiple high-voltage domain switches of the input stage and multiple low-voltage domain switches of the output stage are operated synchronously at a certain frequency to current-isolate the input stage and the output stage across multiple capacitors, the multiple capacitors having multiple input plates respectively connected to the multiple switches of the input stage and multiple output plates respectively connected to the multiple switches of the output stage; Provide analog input signals to the input stage; The differential voltage signal component within the range of the common-mode voltage signal component is transferred from the high voltage domain of the input stage to the low voltage domain of the output stage; Differential amplification of the low-voltage domain differential voltage signal component; as well as Output analog output signal.

2. The method according to claim 1, wherein the frequency is greater than or equal to 100MHz.

3. The method according to claim 1 or claim 2, wherein the common-mode voltage signal component is + / -1000 volts.

4. The method according to any one of claims 1 to 3, wherein the common-mode voltage signal component is + / -100 volts, and wherein the range of the common-mode voltage signal component is + / -100 volts.

5. The method according to any one of claims 1 to 4, wherein the plurality of high-voltage domain switches of the input stage and the plurality of low-voltage domain switches of the output stage are operated synchronously such that a corresponding one of the plurality of switches is the common-mode voltage when open and is at least three volts lower than the common-mode voltage when closed.

6. The method according to any one of claims 1 to 5, wherein the analog input signal comprises a voltage.

7. The method according to any one of claims 1 to 6, wherein the output signal is relative to the reference signal, and the positive output signal and the negative output signal indicate the direction of the current.

8. A monolithic integrated circuit, the monolithic integrated circuit comprising: An input terminal, wherein the input terminal is used to receive analog input signals; Operating coupler, the operating coupler comprising: An input stage, the input stage being coupled to the input terminal and including a plurality of high-voltage domain switches; The output stage includes multiple low-voltage domain switches and a common-mode voltage power supply. A plurality of capacitors, the plurality of capacitors having a plurality of input boards respectively connected to a plurality of high-voltage domain switches and a plurality of output boards respectively connected to a plurality of low-voltage domain switches; and A controller for synchronously operating the plurality of input switches and the plurality of output switches at a certain frequency to charge a corresponding capacitor among the plurality of capacitors; The operating coupler is used to transfer the differential voltage signal component from the high voltage domain to the low voltage domain; A differential amplifier circuit, coupled to the output stage of the operational coupler, amplifies the transferred differential voltage signal component; and An output terminal is coupled to the differential amplifier circuit to output an analog output signal.

9. The monolithic integrated circuit of claim 8, wherein the controller is configured to synchronously operate the plurality of high-voltage domain switches of the input stage and the plurality of low-voltage domain switches of the output stage, such that a corresponding one of the plurality of switches is at the common-mode voltage when open and at least three volts lower than the common-mode voltage when closed.

10. A monolithic integrated circuit, the monolithic integrated circuit comprising: An input terminal, wherein the input terminal is used to receive analog input signals; Operating coupler, the operating coupler comprising: An input stage, the input stage being coupled to the input terminal and including a plurality of high-voltage domain switches; The output stage includes multiple low-voltage domain switches and a common-mode voltage power supply. A plurality of capacitors, the plurality of capacitors having a plurality of input boards respectively connected to a plurality of high-voltage domain switches and a plurality of output boards respectively connected to a plurality of low-voltage domain switches; and A controller is configured to synchronously operate the plurality of high-voltage domain switches and the plurality of low-voltage domain switches at a certain frequency to current isolate the input stage from the output stage and to transfer differential voltage signal components within the range of common-mode voltage signal components from the high-voltage domain to the low-voltage domain. A differential amplifier circuit, the differential amplifier circuit being coupled to the output stage of the operational coupler; and An output terminal is coupled to the differential amplifier circuit to output an analog output signal.

11. The monolithic integrated circuit according to claim 10, wherein the frequency is greater than or equal to 100MHz.

12. The monolithic integrated circuit according to claim 10 or claim 11, wherein the common-mode voltage signal component is + / -1000 volts.

13. The monolithic integrated circuit according to any one of claims 10 to 12, wherein the common-mode voltage signal component is + / -100 volts, and wherein the range of the common-mode voltage signal component is + / -100 volts.

14. The monolithic integrated circuit of claim 13, wherein the controller for synchronously operating the plurality of high-voltage domain switches and the plurality of low-voltage domain switches comprises a corresponding switch among the switches, the corresponding switch being the common-mode voltage when open and at least three volts lower than the common-mode voltage when closed.

15. The monolithic integrated circuit according to any one of claims 10 to 14, wherein the output signal is relative to the reference signal, and the positive output signal and the negative output signal indicate the direction of the current.

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