Isolation amplifier with reference signal transfer

Abstract

An isolated circuit system is provided. The system includes a primary side circuit and a secondary side circuit that are electrically isolated from each other. The primary side circuit and the secondary side circuit each utilize a direct current (DC) reference signal. The primary side circuit may use the DC reference signal in a modulation operation. The secondary side circuit may use the DC reference signal in a demodulation operation. The DC reference signal may be transmitted from the primary side circuit to the secondary side circuit or from the secondary side circuit to the primary side circuit.

Description

[Technical Field]

[0001] Related Applications This application is a continuation of U.S. patent application Ser. No. 16 / 887,812, entitled "ISOLATION AMPLIFIER WITH REFERENCE SIGNAL TRANSFER," filed May 29, 2020, with attorney docket number G0766.70290US00, and is incorporated herein by reference in its entirety.

[0002] This application relates to galvanic isolators that provide galvanic isolation between circuits. [Background technology]

[0003] Isolators provide electrical isolation between circuits that communicate with each other. In some situations, the circuits that communicate with each other operate at different voltages, for example, one at a relatively high voltage and the other at a relatively low voltage. In some situations, the circuits are referenced to different ground potentials. In any of these situations, an isolator can be used to electrically isolate the circuits. Summary of the Invention [Means for solving the problem]

[0004] An isolated circuit system is provided. The system includes a primary side circuit and a secondary side circuit that are electrically isolated from each other. The primary side circuit and the secondary side circuit each utilize a direct current (DC) reference signal. The primary side circuit may use the DC reference signal in a modulation operation. The secondary side circuit may use the DC reference signal in a demodulation operation. The DC reference signal may be transmitted from the primary side circuit to the secondary side circuit or from the secondary side circuit to the primary side circuit.

[0005] According to some embodiments, an isolation amplifier is provided, comprising: a primary side circuit having at least one component configured to operate from a direct current (DC) reference signal; a secondary side circuit having at least one component configured to operate from the DC reference signal; an isolation barrier separating the primary side circuit and the secondary side circuit; a first digital data path configured to transfer digital data across the isolation barrier between the primary side circuit and the secondary side circuit; and a reference signal path configured to transfer the DC reference signal across the isolation barrier between the primary side circuit and the secondary side circuit.

[0006] According to some embodiments, a multi-die isolator system is provided, comprising: a first die having a primary circuit with an encoder configured to employ a bandgap reference signal to encode a data signal; a second die having a secondary circuit with a decoder configured to employ the bandgap reference signal to decode the data signal; an isolator configured to isolate the primary circuit and the secondary circuit from each other; and a reference signal path coupling the first die and the second die and configured to communicate the bandgap reference signal between the primary circuit and the secondary circuit.

[0007] According to some embodiments, a method of operating an isolated circuit system having a primary circuit on a first die and a secondary circuit on a second die includes modulating a data signal at the primary circuit using a direct current (DC) reference signal, transferring the data signal across an isolation barrier from the primary circuit to the secondary circuit, demodulating the data signal at the secondary circuit using the DC reference signal, and communicating the DC reference signal between the primary circuit and the secondary circuit. [Brief explanation of the drawings]

[0008] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures is represented by a like numeral. For clarity, not every component is labeled in every drawing. The drawings include:

[0009] [Figure 1] 1 illustrates an isolator system having a signal path for transferring a reference signal between a primary side circuit and a secondary side circuit of the isolator system. [Figure 2A] 1 illustrates an isolator system comprising a signal path for transferring a reference signal from a primary side circuit to a secondary side circuit of the isolator system, according to a non-limiting embodiment. [Figure 2B] 1 illustrates an isolator system comprising a signal path for transferring a reference signal from a secondary side circuit to a primary side circuit of the isolator system, according to a non-limiting embodiment. [Figure 3] 1 illustrates a capacitively isolated signal transfer for transferring a reference signal, according to a non-limiting embodiment of the present application. [Figure 4] 1 illustrates a capacitor-based isolated signal transfer path for transferring a reference signal, according to a non-limiting embodiment of the present application. [Figure 5] 1 illustrates a transformer-based isolated signal transfer path for transferring a reference signal, according to a non-limiting embodiment of the present application. [Figure 6] 1 is a flowchart illustrating a manner of operating an isolator system according to a non-limiting embodiment of the present application. [Figure 7] FIG. 1 is a schematic diagram illustrating a portable electronic device incorporating an integrated isolator device according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0010] According to one aspect of the present application, an isolation amplifier is configured to transfer a reference signal from the primary side to the secondary side, or vice versa. The isolation amplifier may be used to transfer digital data signals, power signals, or both between isolated domains. The reference signal is a signal used to modulate and demodulate the digital data signals or power signals, and is different from the data signals or power signals. The reference signal may be a direct current (DC) signal.

[0011] According to one aspect of the present application, an isolation amplifier includes (at least) two isolated signal paths: a first (digital) data isolation path and a second analog reference signal isolation path. The reference signal can be used in processing digital signals transmitted via the digital data isolation path. For example, the reference signal can be a reference signal for encoding or decoding circuitry.

[0012] According to one aspect of the present application, an isolation amplifier is provided that includes a primary-to-secondary transmission path for a reference signal. In some embodiments, the transmission path is capacitive. In some embodiments, the transmission path is transformer-based.

[0013] 1 illustrates an isolator system 100 having a signal path for transferring a reference signal between a primary circuit and a secondary circuit of the isolator system. The isolator system 100 includes a primary circuit 102, a secondary circuit 104, a first signal path 106a, a second signal path 106b, a first isolation component 108a, and a second isolation component 108b. The isolation components 108a and 108b enable signal transfer across an isolation barrier 110.

[0014] The primary circuit 102 may include transmitter and / or receiver electronics. In some embodiments, the primary circuit 102 is an integrated circuit formed on a semiconductor die or chip. The secondary circuit 104 may similarly include transmitter and / or receiver electronics. In some embodiments, the secondary circuit 104 is an integrated circuit formed on a semiconductor die. Thus, in some embodiments, the isolator system 100 comprises a primary integrated circuit on a first chip, a secondary integrated circuit on a second chip, and an isolation barrier 110 that electrically isolates the primary integrated circuit from the secondary integrated circuit. The isolation barrier may be a dielectric layer.

[0015] The first signal path 106a and the second signal path 106b may be configured to transfer different types of signals, one of which is a reference signal. For example, the first signal path 106a may carry an analog reference signal between the primary circuit 102 and the secondary circuit 104. The reference signal may be used as a reference by circuit components on both the primary circuit 102 and the secondary circuit 104. The second signal path 106b may carry a digital data signal, a power signal, or both. The first signal path 106a includes an isolation component 108a, which may be a transformer, a capacitor, or another type of isolator. The second signal path 106b includes an isolation component 108b, which may be a transformer, a capacitor, or another type of isolator. The isolation components 108a and 108b may be the same type of isolation component, e.g., a capacitor or a transformer, although not all embodiments are limited in this respect.

[0016] 2A illustrates an isolator system including a signal path for transferring a reference signal from a primary-side circuit to a secondary-side circuit of the isolator system, according to a non-limiting embodiment. Accordingly, FIG. 2A illustrates a non-limiting implementation of the isolator system 100. The isolator system 200 includes a primary-side circuit 202 and a secondary-side circuit 204 separated by an isolation barrier 206. The primary-side circuit 202 includes a driver 208, an encoder 210, and a bandgap signal generator 212. The secondary-side circuit 204 includes a decoder 214, an amplifier 216, and a low-offset buffer 218.

[0017] 2B illustrates an isolator system including a signal path for transferring a reference signal from the secondary side circuitry to the primary side circuitry of the isolator system, according to a non-limiting embodiment. The isolator system 250 of FIG. 2B includes the same components as the isolator system 200 of FIG. 1. However, the bandgap generator 212 and the low-offset buffer 218 have been swapped on opposite sides of the isolator system. Thus, the reference signal can be transmitted from the secondary side circuitry to the primary side circuitry.

[0018] 2A and 2B, it can be seen that an embodiment of the present application provides a primary-side circuit having at least one component configured to operate from a direct current (DC) reference signal and a secondary-side circuit having at least one component configured to operate from the DC reference signal. In some embodiments, a first integrated circuit die comprises the primary-side circuit and a second integrated circuit die comprises the secondary-side circuit. According to one embodiment, at least one component of the primary-side circuit is an analog-to-digital converter (ADC), and at least one component of the secondary-side circuit is a digital-to-analog converter (DAC). According to one embodiment, at least one component of the primary-side circuit is an encoder, and at least one component of the secondary-side circuit is a decoder.

[0019] 2A and 2B, it can be understood that a multi-die isolator system can be provided, including a first die having a primary circuit with an encoder configured to employ a bandgap reference signal to encode a data signal, and a second die having a secondary circuit with a decoder configured to employ the bandgap reference signal to decode the data signal. An isolator can be configured to isolate the primary and secondary circuits from each other, and a reference signal path can be provided coupling the first and second dies and configured to communicate the bandgap reference signal between the primary and secondary circuits.

[0020] FIG. 3 illustrates an isolated signal path for transferring a reference signal according to a non-limiting embodiment of the present application. As shown in FIG. 2A, the reference signal can be transferred from the primary side circuit to the secondary side circuit. This can be achieved using the circuit blocks illustrated in FIG. 3. The isolated signal path 300 includes an amplitude modulation (AM) block 302 that receives a reference signal (VREF1a) and modulates its amplitude. The reference signal VREF1a provided to the AM modulation block 302 can be an AC signal generated from a DC reference signal used in the primary side circuit. Therefore, the reference signal path is configured to convert the DC reference signal to an AC value before it is transferred across the isolation barrier. The AM-modulated reference signal can be transferred across the isolation barrier 206 using a suitable technique, such as capacitive or inductive coupling. Examples are provided below in connection with FIGS. 4 and 5. On the secondary side of the isolator, the received reference signal can be demodulated using an amplitude demodulation block 304. The output of the amplitude demodulation block 304 can be filtered by a low-pass filter 306. Because the reference signal is a DC signal, the use of a low-pass filter 306 is appropriate. The low-pass filtered reference signal may then be provided to a low-offset buffer 308. The low-offset buffer 308 outputs the forwarded reference signal VREF1b, for example, to circuit components in the secondary side circuit that use the reference signal as a reference. For example, the low-offset buffer 308 may output the forwarded reference signal to a decoder, as shown in FIG. 2A. Optionally, the low-offset buffer 308 may provide gain calibration.

[0021] Figure 4 shows a non-limiting example of a circuit implementation of isolated signal path 300 of Figure 3, which includes a capacitive signal transfer path for transferring a reference signal. Accordingly, it should be understood that the circuit components of Figure 4 represent non-limiting examples of circuit components that may be implemented in an isolator system such as that of Figure 2A. As shown, isolated signal path 400 includes a signal chopper 402 on the primary side of isolation barrier 206, a low-offset buffer 404, capacitors 406a and 406b, and a signal chopper 408.

[0022] Signal choppers 402 and 408 may be any suitable signal choppers. Signal chopper 402 may perform amplitude modulation of a reference signal transferred across isolation barrier 206. Signal chopper 408 may perform amplitude demodulation of the transferred reference signal. Thus, signal chopper 402 represents one implementation of amplitude modulation block 302, and signal chopper 408 represents one implementation of amplitude demodulation block 304.

[0023] As shown, both signal choppers are differential. The use of differential signal choppers facilitates differential signal transmission across the isolation barrier 206, which may be beneficial for robust signal transfer and avoid the noise and offset drawbacks associated with single-ended signal transmission. The reference signal may be input to the signal chopper 402 as a differential AC signal.

[0024] Capacitors 406a and 406b may be configured to provide low-pass filtering. As such, these capacitors represent non-limiting implementations of low-pass filter 306. They may have any suitable value to provide the desired low-pass filtering performance.

[0025] Low-offset buffer 404 is shown as a differential buffer consistent with the differential signaling scheme of isolated signal path 400. Low-offset buffer 404 is a non-limiting implementation of low-offset buffer 308 of Figure 3. Low-offset buffer 404 outputs a reference signal consistent with low-offset buffer 308 of Figure 3.

[0026] 5 shows another non-limiting example of a circuit implementation of isolated signal path 300 of FIG. 3, comprising a transformer-based isolated signal transfer path for transferring a reference signal. Isolated signal path 500 comprises driver 502, switch 504, primary coil 506, and cross-coupled switches 508a and 508b. On the secondary side of the isolated signal path are secondary coil 510, cross-coupled switches 512a and 512b, and capacitor 514.

[0027] Driver 502 receives reference signal VREF at its positive terminal and outputs a signal that controls switch 504. Cross-coupled switches 508a and 508b cause oscillation, which allows primary coil 506 to transmit an AC signal to secondary coil 510. Cross-coupled switches 512a and 512b operate to demodulate the signal, and capacitor 514 functions as a low-pass filter. Thus, the reference signals at nodes 516 and 518 are substantially equal, and in this way, a DC reference signal can be transferred over an isolated signal path.

[0028] 6 is a flowchart illustrating a manner of operating an isolator system according to a non-limiting embodiment of the present application. Method 500 begins with modulating a data signal in a primary circuit using a direct current (DC) reference signal at step 502. The DC reference signal may be an analog signal.

[0029] At step 604, the method 600 includes transferring a data signal across the isolation barrier from the primary circuit to the secondary circuit. The data signal may be a digital data signal.

[0030] In step 606, the method 600 includes communicating a DC reference signal between the primary circuit and the secondary circuit.

[0031] In step 608, the method includes demodulating the data signal in a secondary circuit using the DC reference signal from step 602.

[0032] FIG. 7 illustrates an apparatus that may employ an isolator system according to an embodiment of the present application.

[0033] Integrated isolator devices of the type described herein can be used in a variety of devices and settings. For example, integrated isolator devices can be used for isolation in medical equipment systems, industrial equipment systems, physical measurement systems, or personal or portable electronic devices. FIG. 7 is a schematic diagram illustrating a non-limiting application of an integrated isolator system in a portable electronic device setting, according to some embodiments. Integrated isolator system 700 can be used in a portable electronic device 701 to transmit power or data across an isolation barrier. Portable electronic device 701 can be a smartphone, personal digital assistant (PDA), tablet, or other handheld device. Other such devices can utilize integrated isolator systems of the type described herein.

[0034] 7 shows one example of a portable electronic device 701 incorporating aspects of the present application, although other uses are possible. For example, one or more integrated isolator systems 700 may be employed in automobiles or medical equipment. Various embodiments of the present application may be implemented to provide high transfer efficiency and high isolation ratings at high operating frequencies.

[0035] The integrated isolator devices described herein can be used in a variety of applications (e.g., industrial, medical, consumer). For example, data and / or power transfer between electrically isolated systems can be achieved using the integrated isolator devices described herein. As one example, medical equipment in a room where a medical procedure is being performed can be electrically isolated from a control system in a control room. For example, a collection of medical imaging equipment and / or monitors in a room where a procedure is being performed can be isolated from the system that controls the operation of the imaging equipment and / or display. The isolator can be any of the types of integrated isolator devices and / or systems described herein, and the isolated signal path can be analog or digital.

[0036] As another example, industrial equipment may be isolated from the control systems that control the equipment. For example, high wattage motors may be isolated from the control systems that control their operation by an integrated isolator device of the type described herein. The control systems may operate at lower wattages than the high wattage motors used by the industrial equipment. The isolator may be located on a circuit board that includes various circuit components connected to the motors and / or control equipment.

[0037] The examples of integrated isolator devices described herein are non-limiting and other uses thereof are possible.

[0038] The terms "approximately" and "about" may be used to mean, in some embodiments, within ±20% of a target value, in some embodiments, within ±10% of a target value, in some embodiments, within ±5% of a target value, and even in some embodiments, within ±2% of a target value. The terms "approximately" and "about" may include the target value.

Claims

1. 1. An isolation amplifier, comprising: a primary side circuit having at least one component configured to operate from a direct current (DC) reference signal; a secondary side circuit having at least one component configured to operate from the DC reference signal; an isolation barrier separating the primary side circuit from the secondary side circuit; a first digital data path configured to transfer digital data across the isolation barrier between the primary side circuitry and the secondary side circuitry; a reference signal path configured to transfer the DC reference signal across the isolation barrier between the primary side circuit and the secondary side circuit, the primary side circuit comprises a driver receiving the DC reference signal, a switch connected to the driver, a primary coil connected to the switch, and a first cross-coupled switch connected to the primary coil, the first cross-coupled switch causing oscillation, and the primary coil transmitting an AC signal to the secondary side circuit; the secondary side circuit includes a secondary coil that receives the AC signal; and a second cross-coupled switch that is connected to the secondary coil and that demodulates the AC signal. Isolation amplifier.

2. 2. The isolation amplifier of claim 1, wherein the reference signal path is configured to convert the DC reference signal to an AC value before the DC reference signal is transferred across the isolation barrier.

3. 2. The isolation amplifier of claim 1, wherein the reference signal path is configured to capacitively transfer the DC reference signal across the isolation barrier.

4. 10. The isolation amplifier of claim 1, wherein the reference signal path is configured to inductively transfer the DC reference signal across the isolation barrier.

5. 10. The isolation amplifier of claim 1, further comprising: a first integrated circuit die comprising the primary side circuitry; and a second integrated circuit die comprising the secondary side circuitry.

6. 10. The isolation amplifier of claim 1, wherein the at least one component of the primary side circuit is an analog-to-digital converter (ADC).

7. 7. The isolation amplifier of claim 6, wherein the at least one component of the secondary side circuit is a digital-to-analog converter (DAC).

8. 2. The isolation amplifier of claim 1, wherein the at least one component of the primary side circuit is an encoder and the at least one component of the secondary side circuit is a decoder.

9. 10. The isolation amplifier of claim 1, wherein the reference signal path comprises an amplitude modulation circuit configured to encode the DC reference signal as an amplitude modulated analog signal.

10. 1. A multi-die isolator system comprising: a first die having a primary circuit with an encoder configured to employ a bandgap reference signal to encode a data signal; a second die having a secondary circuit with a decoder configured to employ the bandgap reference signal to decode the data signal; an isolator configured to isolate the primary circuit and the secondary circuit from each other; a reference signal path coupling the first die and the second die and configured to communicate the bandgap reference signal between the primary circuit and the secondary circuit, the primary circuit comprises a driver receiving a DC reference signal, a switch connected to the driver, a primary coil connected to the switch, and a first cross-coupled switch connected to the primary coil, the first cross-coupled switch inducing oscillation and the primary coil transmitting an AC signal to the secondary circuit; the secondary circuit comprising: a secondary coil that receives the AC signal; and a second cross-coupled switch that is connected to the secondary coil and that demodulates the AC signal. Multi-die isolator system.

11. 11. The multi-die isolator system of claim 10, wherein the bandgap reference signal is a direct current (DC) signal, and the reference signal path is configured to amplitude modulate the bandgap reference signal to communicate the bandgap reference signal between the primary circuit and the secondary circuit.

12. 11. The multi-die isolator system of claim 10, wherein the encoder is an analog-to-digital converter (ADC) and the decoder is a digital-to-analog converter (DAC).

13. 11. The multi-die isolator system of claim 10, wherein the reference signal path is configured to communicate the bandgap reference signal from the primary circuit to the secondary circuit.

14. 14. The multi-die isolator system of claim 13, wherein the reference signal path is configured to communicate the bandgap reference signal from the secondary circuit to the primary circuit.

15. 11. The multi-die isolator system of claim 10, wherein the reference signal path comprises a capacitive coupler.

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