Power supply device and sensor unit

The power supply device in IMUs uses a current-mode bandgap reference circuit with switching configurations to stabilize reference voltages and currents, addressing noise and inefficiencies in IMUs by providing a stable and efficient power supply for accelerometers and gyroscopes.

WO2026099103A1PCT designated stage Publication Date: 2026-05-15ROBERT BOSCH GMBH
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
ROBERT BOSCH GMBH
Filing Date
2025-11-03
Publication Date
2026-05-15

AI Technical Summary

Technical Problem

Inertial measurement units (IMUs) face challenges in providing stable, temperature-independent electrical quantities due to the use of separate bandgap reference sources for accelerometers and gyroscopes, leading to noise and inefficiencies.

Method used

A power supply device with a current-mode bandgap reference circuit and switching configurations for transistors, which alternately connects transistors to a control loop to provide precise control potentials and currents, reducing noise and improving efficiency.

Benefits of technology

The solution achieves a more constant and noise-reduced electrical output, enabling a compact and energy-efficient operation of sensor units by stabilizing reference voltages and currents across different sensor elements.

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Abstract

The invention relates to a power supply device (10) for outputting at least one output current (12), comprising at least one first transistor (18) having a first control connection (16) for outputting a first output current (20) depending on a first control potential (22) at the first control connection (16) via a first output connection (24), and a second transistor (28) having a second control connection (26) for outputting a second output current (30) depending on a second control potential (32) at the second control connection (26) via a second output connection (34), a control circuit (48) having at least one operational amplifier (46), a switching device (50) which can be switched at least between a first switching configuration, in which the first transistor (18) is electrically connected to the control circuit (48) and the second transistor (28) for outputting the second output current (30) is electrically connected to the second output connection (34), and a second switching configuration, in which the second transistor (28) is electrically connected to the control circuit (48) and the first transistor (18) for outputting the first output current (20) is electrically connected to the first output connection (24). The invention also relates to a sensor unit (94).
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Description

[0001] R. 416098

[0002] - 1 -

[0003] Description

[0004] title

[0005] Power supply device and sensor unit

[0006] The invention relates to a power supply device according to claim 1. The invention further relates to a sensor unit with such a power supply device.

[0007] State of the art

[0008] In inertial measurement units (IMUs), bandgap reference sources provide stable, temperature-independent electrical quantities, such as a reference voltage or reference current. Typically, one bandgap reference source is used for the accelerometer and another for the gyroscope.

[0009] Disclosure of the invention

[0010] According to the present invention, a power supply device with the features of claim 1 is proposed. This allows the power supply device to provide a more constant, noise-reduced, and independent electrical output.

[0011] The output current is an electrical output current. The control potential is an electrical control potential. The control loop is an electrical control loop. The output current can be a constant current.

[0012] The power supply device can output a constant current. The constant current can produce a constant voltage across a reference resistor. The power supply device can thereby output a constant voltage. The output constant voltage can be greater than or equal to 300 mV, in particular greater than or equal to 800 mV. R. 416098

[0013] - 2 -

[0014] The power supply device can be a current-mode bandgap reference circuit. The power supply device can include a PTAT (proportional to absolute temperature) reference circuit and / or a CTAT (complementary to absolute temperature) reference circuit. The power supply device can be associated with a bandgap temperature sensor or a current-to-voltage converter.

[0015] The power supply device can have at least one further transistor having a further control terminal for outputting a further output current depending on a further control potential at the further control terminal via a further output terminal.

[0016] The output current can be a bias current for operating at least one component, for example an operational amplifier.

[0017] The first, second and / or subsequent transistor can be a field-effect transistor, in particular a MOSFET, preferably a PMOS.

[0018] The operational amplifier can be a differential amplifier. Low-frequency noise can be reduced by the gain of the operational amplifier in the control loop.

[0019] The switching device is configured to output the first and second output currents with a time delay. The first and second output currents can be output at a common output terminal. The first and second output terminals can be connected to the common output terminal. The first and second output currents can form a single output current at the common output terminal. The first and second output currents can be output at separate output terminals. For example, the first output terminal can be connected to an accelerometer and the second output terminal to a gyroscope.

[0020] In a preferred embodiment of the invention, it is advantageous if, in the first switching configuration, the second transistor is electrically decoupled from the control loop and the first transistor is electrically decoupled from the first output terminal. In the first switching configuration, the first control potential can be adjustable by the control loop. The first control potential can be built up during the first switching configuration and used for R. 416098

[0021] - 3 -

[0022] The retrieval can be stored at a time outside of the first switching configuration, especially during the second switching configuration.

[0023] A preferred embodiment of the invention is advantageous in which, in the second switching configuration, the first transistor is electrically decoupled from the control loop and the second transistor is electrically decoupled from the second output terminal. In the second switching configuration, the second control potential can be set by the control loop. The second control potential can be built up during the second switching configuration and stored for retrieval outside of the second switching configuration, particularly during the first switching configuration.

[0024] In a preferred embodiment of the invention, the output of the first transistor is connected to at least one input of the operational amplifier, and the first control terminal is connected to the output of the operational amplifier. In the first switching configuration, the first transistor can be integrated into the control loop of the operational amplifier. The first output current can serve as the controlled variable by adjusting the first control potential during the first switching configuration.

[0025] In a particular embodiment of the invention, it is advantageous if, in the second switching configuration, the output of the second transistor is connected to at least one input of the operational amplifier and the second control terminal is connected to the output of the operational amplifier. In the second switching configuration, the second transistor can be integrated into the control loop of the operational amplifier. The second output current can form the controlled variable by setting the second control potential during the first switching configuration.

[0026] In a preferred embodiment of the invention, it is advantageous if the switching device comprises at least a first switching element between the output of the operational amplifier and the first control terminal, a second switching element between the first transistor and the first output terminal, a third switching element between the output of the operational amplifier and the second control terminal, and a fourth switching element between the second transistor and the second output terminal. In the first switching configuration, the first and fourth switching elements are closed, and the second and third switching elements are open. (See R. 416098)

[0027] - 4 - In the second switching configuration, the first and fourth switching elements are open and the second and third switching elements are closed.

[0028] In an advantageous embodiment of the invention, the switching device comprises a fifth switching element between the output of the first transistor and an input of the operational amplifier, and a sixth switching element between the output of the second transistor and an input of the operational amplifier. In the first switching configuration, the fifth switching element is closed and the sixth switching element is open. In the second switching configuration, the fifth switching element is open and the sixth switching element is closed.

[0029] A preferred embodiment of the invention is advantageous in which a first capacitor is connected to the first control terminal. In the first switching configuration, this capacitor exhibits a voltage specified by the control loop, and in the second switching configuration, it provides the first control potential. The first capacitor can be arranged between the input of the first transistor and the first control terminal. The voltage across the first capacitor can constitute the control voltage between the input and the first control terminal, particularly during the second switching configuration.

[0030] In a preferred embodiment of the invention, a second capacitor is connected to the second control terminal. In the second switching configuration, this capacitor assumes a voltage specified by the control loop, while in the first switching configuration, it provides the second control potential. The second capacitor can be arranged between the input of the second transistor and the second control terminal. The voltage across the second capacitor can constitute the control voltage between the input and the second control terminal, particularly during the first switching configuration.

[0031] The operational amplifier can be operated via chopping, particularly to reduce 1 / f noise. If residual ripple exists, a notch filter can be used. The first and / or second capacitor can also be part of a sampling circuit within the notch filter.

[0032] According to the present invention, a sensor unit with the features of claim 10 is further proposed. The sensor unit can be an inertial measurement unit R. 416098.

[0033] - 5 - The sensor element can be an accelerometer or a gyroscope. The sensor unit can have at least two sensor elements, in particular an accelerometer and a gyroscope. The power supply device can supply electrical power to both the accelerometer and the gyroscope. This allows the sensor unit to be more compact and operate more energy-efficiently. The first output terminal can be connected to the accelerometer and the second output terminal to the gyroscope.

[0034] Furthermore, an integrated circuit with such a power supply device is proposed. The integrated circuit can be a sensor ASIC of the sensor unit.

[0035] Further advantages and advantageous embodiments of the invention will become apparent from the description of the figures and the illustrations.

[0036] Character description

[0037] The invention is described in detail below with reference to the illustrations. These show, in detail:

[0038] Figures 1 to 3: A power supply device, each in a specific embodiment of the invention.

[0039] Figure 4: A sensor unit in a special embodiment of the invention.

[0040] The power supply device 10 in Figure 1 is designed as a PTAT reference circuit 14 for outputting at least one output current 12 and comprises a first transistor 18 having a first control terminal 16 for outputting a first output current 20 depending on a first control potential 22 at the first control terminal 16 via a first output terminal 24, and a second transistor 28 having a second control terminal 26 for outputting a second output current 30 depending on a second control potential 32 at the second control terminal 26 via a second output terminal 34. The first and second R. 416098

[0041] - 6 -

[0042] Transistor 18, 28 is preferably a field-effect transistor, in particular a PMOS.

[0043] The first and second transistors 18, 28 are connected to an input potential 36 of a supply voltage. A first capacitor 40 is located between the input 38 of the first transistor 18 and the first control terminal 16, and a second capacitor 44 is located between the input 42 of the second transistor 28 and the second control terminal 26.

[0044] Furthermore, the power supply device 10 comprises a control circuit 48 having at least one operational amplifier 46 and a switching device 50, which is switchable between at least a first switching configuration and a second switching configuration. The switching device 50 comprises a first switching element 52 between the output 54 of the operational amplifier 46 and the first control terminal 16, a second switching element 56 between the first transistor 18 and the first output terminal 24, a third switching element 58 between the output 54 of the operational amplifier 46 and the second control terminal 26, a fourth switching element 60 between the second transistor 28 and the second output terminal 34, a fifth switching element 62 between the output 64 of the first transistor 18 and an input 66 of the operational amplifier 46, and a sixth switching element 68 between the output 70 of the second transistor 28 and the input 66 of the operational amplifier 46.

[0045] In the first switching configuration, the first, fourth, and fifth switching elements 52, 60, 62 are closed, and the second, third, and sixth switching elements 56, 58, 68 are open. In the second switching configuration, the second, third, and fifth switching elements 56, 58, 62 are open, and the first, fourth, and sixth switching elements 52, 60, 68 are closed. Thus, in the first switching configuration, the first transistor 18 is electrically connected to the control loop 48, and the second transistor 28, for outputting the second output current 30, is electrically connected to the second output terminal 34 and decoupled from the control loop 48. In the second switching configuration, the second transistor 28 is electrically connected to the control loop 48, and the first transistor 18, for outputting the first output current 20, is electrically connected to the first output terminal 24 and electrically decoupled from the first output terminal 24. R. 416098

[0046] - 7 -

[0047] In the first switching configuration, the output 64 of the first transistor 18 is connected via the closed fifth switching element 62 and a first resistor 72 to a first input 73 of the operational amplifier 46, and via a second resistor 74 to a second input 75 of the operational amplifier 46. The first control terminal 16 is connected via the closed first switching element 52 to the output 54 of the operational amplifier 46. In the second switching configuration, the output 70 of the second transistor 28 is connected via the closed sixth switching element 68 and the first resistor 72 to the first input 73 of the operational amplifier 46, and via the second resistor 74 to the second input 75 of the operational amplifier 46. The second control terminal 26 is connected via the closed second switching element 56 to the output 54 of the operational amplifier 46.

[0048] In the second switching configuration, the voltage across the first capacitor 40 forms the control voltage between the input 38 of the first transistor 18 and the first control terminal 16, thus causing the first output current 20 at the first output terminal 24. In the first switching configuration, the voltage across the second capacitor 44 forms the control voltage between the input 42 of the second transistor 28 and the second control terminal 26, thus causing the second output current 30 at the second output terminal 34. The first and second output terminals 24 and 34 are connected to a common output terminal 76, which outputs the first and second output currents 20 and 30 as a common output current 12.

[0049] The switching device 50 is configured to switch the first and second switching configurations alternately, thereby alternately providing the first output current 20 and the second output current 30 as a common output current 12 at the common output terminal 76. By adjusting the voltage across the first capacitor 40 via the control loop 48 in the first switching configuration, precise adjustment of the first control potential 22 or the control voltage can be achieved, and thus, in the subsequent second switching configuration, precise output of the first output current 20 can be obtained. During the first switching configuration, the second output current 30 is output, and during the second switching configuration, the voltage across the second capacitor 44 is adjusted via the control loop 48. R. 416098

[0050] - 8 -

[0051] This avoids the deviations that arise in conventional current mirroring due to the mirroring of the control potential across different transistors, since each control potential is precisely controlled. Furthermore, the noise present at the individual transistors can be accounted for and reduced through this control.

[0052] Figure 2 shows a power supply device 10 with several branches 78, i.e., in addition to the first transistor 18 and the second transistor 28, with two further transistors 80. Depending on further switching configurations, the switching device 50, which has additional switching elements, can be connected to the control circuit 48 or the associated further output terminals 82 in addition to the first and second switching configurations. Each branch 78 has three switching elements 84 that connect the respective transistor to the control circuit 48 or the respective output terminal. The switching configurations can be adopted sequentially. The branches 78 with higher requirements for the quality of the output current can also be switched more frequently than the other branches 78.

[0053] For example, a branch 86 can provide a constant voltage to a gyroscope of a sensor unit via a first reference resistor 87, another branch 88 can provide a constant voltage to an accelerometer of the sensor unit via a second reference resistor 89, and another branch 90 can provide a constant bias current.

[0054] In Figure 3, the power supply device 10 from Figure 1 is extended by a CTAT reference circuit 92. The PTAT reference circuit 14 provides, as its first branch, an output current 12 that is proportional to a temperature, and the CTAT reference circuit 92 provides, as its second branch, an output current 12 that is inversely proportional to a temperature.

[0055] Figure 4 shows a sensor unit 94 in a special embodiment of the invention. The sensor unit 94 comprises an accelerometer 96 as the first sensor element and a gyroscope 98 as the second sensor element, and a power supply device 10, as shown, for example, in Figure 2, for supplying electrical power to the sensor elements, here the accelerometer 96 and the gyroscope.

Claims

R. 416098 - 9 - Patent claims 1. Power supply device (10) for outputting at least one output current (12), comprising at least one first transistor (18) having a first control terminal (16) for outputting a first output current (20) depending on a first control potential (22) at the first control terminal (16) via a first output terminal (24) and a second transistor (28) having a second control terminal (26) for outputting a second output current (30) depending on a second control potential (32) at the second control terminal (26) via a second output terminal (34), a control circuit (48) comprising at least one operational amplifier (46), a switching device (50) which connects at least between a first switching configuration,in which the first transistor (18) is electrically connected to the control loop (48) and the second transistor (28) is electrically connected to the second output terminal (34) for the output of the second output current (30), and is switchable to a second switching configuration in which the second transistor (28) is electrically connected to the control loop (48) and the first transistor (18) is electrically connected to the first output terminal (24) for the output of the first output current (20).

2. Power supply device (10) according to claim 1, characterized in that in the first switching configuration the second transistor (28) is electrically decoupled from the control circuit (48) and the first transistor (18) is electrically decoupled from the first output terminal (24).

3. Power supply device (10) according to claim 1 or 2, characterized in that in the second switching configuration the first transistor (18) is electrically decoupled from the control circuit (48) and the second transistor (28) is electrically decoupled from the second output terminal (34). R. 416098 - 10 - 4. Power supply device (10) according to one of the preceding claims, characterized in that in the first switching configuration the output (64) of the first transistor (18) is connected to at least one input (66) of the operational amplifier (46) and the first control terminal (16) is connected to the output (54) of the operational amplifier (46).

5. Power supply device (10) according to one of the preceding claims, characterized in that in the second switching configuration the output (70) of the second transistor (28) is connected to at least one input (66) of the operational amplifier (46) and the second control terminal (26) is connected to the output (54) of the operational amplifier (46).

6. Power supply device (10) according to one of the preceding claims, characterized in that the switching device (50) has at least a first switching element (52) between the output (54) of the operational amplifier (46) and the first control terminal (16), a second switching element (56) between the first transistor (18) and the first output terminal (24), a third switching element (58) between the output (54) of the operational amplifier (46) and the second control terminal (26) and a fourth switching element (60) between the second transistor (28) and the second output terminal (34).

7. Power supply device (10) according to claim 6, characterized in that the switching device (50) has a fifth switching element (62) between the output (64) of the first transistor (18) and an input (66) of the operational amplifier (46) and a sixth switching element (68) between the output (70) of the second transistor (28) and an input (66) of the operational amplifier (46).

8. Power supply device (10) according to one of the preceding claims, characterized in that a first capacitor (40) is connected to the first control terminal (16), which in the first switching configuration R. 416098 - 11 - assumes a voltage specified by the control loop (48) and causes the first control potential (22) in the second switching configuration.

9. Power supply device (10) according to one of the preceding claims, characterized in that a second capacitor (44) is connected to the second control terminal (26), which in the second switching configuration assumes a voltage specified by the control loop (48) and which in the first switching configuration effects the second control potential (32).

10. Sensor unit (94) comprising at least one sensor element (96, 98) and a power supply device (10) according to one of the preceding claims for supplying electrical power to the sensor element (96, 98).