US-12618867-B2 - Sensor package with interference reduction and method of operation

US12618867B2US 12618867 B2US12618867 B2US 12618867B2US-12618867-B2

Abstract

A sensor package includes a first die having a capacitor sensor that includes an active sensing portion and a shield surrounding the active sensing portion. The sensor package further includes a second die that includes a voltage regulator configured to produce a shield voltage and a compensation circuit configured to produce a compensation signal. The voltage regulator and the compensation circuit are electrically coupled to the shield. The voltage regulator is configured to regulate the shield to the shield voltage and the compensation signal produced by the compensation circuit is configured to reduce an interference signal on the shield voltage. The compensation circuit includes one or more coupling capacitors that may be programmable capacitor arrays and calibration methodology entails selecting capacitance values for the programmable capacitor arrays that minimizes the error on an output signal of the sensor package.

Inventors

JEROME ROMAIN ENJALBERT

Assignees

STMICROELECTRONICS INTERNATIONAL N.V.

Dates

Publication Date: 20260505
Application Date: 20211130
Priority Date: 20201201

Claims (19)

1 . A sensor package comprising: a first die having a capacitive sensor, the capacitive sensor including an active sensing portion having moveable masses and a shield surrounding the active sensing portion; and a second die comprising a voltage regulator configured to produce a shield voltage and a compensation circuit configured to produce a compensation signal, the voltage regulator and the compensation circuit being electrically coupled to the shield, wherein a terminal of a coupling capacitor of the compensation circuit is connected to a terminal of the voltage regulator to produce the shield voltage, and wherein the voltage regulator is configured to regulate the shield to the shield voltage, and the compensation signal produced by the compensation circuit is configured to reduce an interference signal on the shield voltage; wherein the sensor package further comprises a package substrate having a package lead; and an off-chip bond wire is electrically connected between an off-chip bond pad on the second die and the package lead, wherein a communication signal is provided to the compensation circuit of the second die via the off-chip bond wire, the communication signal imposing the interference signal on the shield voltage, the interference signal further including a voltage which couples from the package lead of the sensor package through a parasitic capacitance and a bulk silicon of the first die to the shield which is located between the bulk silicon of the first die and the active sensing portion; wherein the communication signal is a serial data acquisition signal originating external to the sensor package or serial clock signal originating external to the sensor package, the serial data acquisition signal and serial clock signal conforming to a data communication protocol.
2 . The sensor package of claim 1 wherein the compensation circuit is configured to produce the compensation signal having an equivalent magnitude and opposite polarity to the interference signal.
3 . The sensor package of claim 1 wherein the communication signal comprises a digital communication signal from an electronic component external to the sensor package.
4 . The sensor package of claim 1 wherein: the sensor package further comprises an inter-chip bond wire electrically connecting first and second bond pads of the respective first and second dies, the shield voltage and the compensation signal being provided to the first die via the inter-chip bond wire; and the compensation circuit comprises: a logic invertor having an input and an output, the input being electrically connected to the off-chip bond pad on the second die; and the coupling capacitor having a first terminal electrically connected to the output of the logic inverter and a second terminal electrically connected to the second bond pad.
5 . The sensor package of claim 4 wherein: the logic inverter is configured to receive the communication signal at the input and invert the communication signal to produce an inverted communication signal; and the coupling capacitor is configured to receive the inverted communication signal at the first terminal, the inverted communication signal driving the coupling capacitor to produce the compensation signal having an opposite polarity to the interference signal.
6 . The sensor package of claim 4 wherein: the package substrate has a second package lead; and the sensor package further comprises a second off-chip bond wire electrically connected between a second off-chip bond pad on the second die and the second package lead, wherein a second communication signal is provided to the second die via the second off-chip bond wire, the second communication signal imposing a second interference signal on the shield voltage; and the compensation circuit further comprises: a second logic invertor having a second input and a second output, the second input being electrically connected to the second off-chip bond pad on the second die; and a second coupling capacitor having a third terminal electrically connected to the second output of the second logic inverter and a fourth terminal electrically connected to the second bond pad, wherein the second coupling capacitor is configured to produce a second compensation signal configured to reduce the second interference signal on the shield voltage.
7 . The sensor package of claim 1 wherein the compensation circuit comprises a programmable capacitor array configured to provide a variable capacitance.
8 . The sensor package of claim 7 wherein the second die further comprises processing circuitry coupled to the programmable capacitor array, the processing circuitry being configured to determine a capacitance value for the programmable capacitor array for producing the compensation signal.
9 . A method of operating a sensor in a sensor package that includes a first die and a second die, the first die having a capacitive sensor, the capacitive sensor including an active sensing portion having moveable masses and a shield surrounding the active sensing portion, and the second die including a voltage regulator and a compensation circuit directly electrically coupled to the shield, a method comprising: providing a shield voltage from the voltage regulator to the shield to regulate the shield to the shield voltage; detecting an interference signal imposed on the shield voltage; producing a compensation signal at the compensation circuit in response to the interference signal; and providing the compensation signal from the compensation circuit to the shield to reduce the interference signal on the shield voltage; wherein an terminal of the voltage regulator is coupled to a terminal of a coupling capacitor of the compensation circuit to produce the shield voltage; and wherein an off-chip bond wire is electrically connected between an off-chip bond pad on the second die and a package lead of a package substrate, wherein a communication signal is provided to the compensation circuit of the second die via the off-chip bond wire, the communication signal imposing the interference signal on the shield voltage, the interference signal further including a voltage which couples from the package lead of the sensor package through a parasitic capacitance and a bulk silicon of the first die to the shield which is located between the bulk silicon of the first die and the active sensing portion; wherein the communication signal is a serial data acquisition signal originating external to the sensor package or serial clock signal originating external to the sensor package, the serial data acquisition signal and serial clock signal conforming to a data communication protocol.
10 . The method of claim 9 wherein the compensation signal has an equivalent magnitude and opposite polarity to the interference signal.
11 . The method of claim 9 further comprising calibrating the compensation circuit to produce the compensation signal.
12 . The method of claim 11 wherein the calibrating operation comprises: measuring a baseline signal output of the capacitive sensor; driving a signal transition on a communication line of the sensor package, the signal transition imposing the interference signal on the shield voltage; and determining a capacitance value for the coupling capacitor of the compensation circuit in response to the baseline signal output and the interference signal.
13 . The method of claim 12 wherein the calibrating operation further comprises: measuring an output signal of the sensor package in response to imposition of the interference signal on the shield voltage; comparing the output signal to the baseline signal output of the capacitive sensor; and the determining the capacitance value comprises selecting the capacitance value for the coupling capacitor that minimizes the difference between the output signal and the baseline signal output.
14 . The method of claim 13 wherein the coupling capacitor comprises a programmable capacitor array, and the determining comprises: sweeping variable capacitance values of the programmable capacitor array to select the capacitance value that minimizes the difference between the output signal and the baseline signal output; and storing the selected capacitance value in a memory element of the sensor package for using during operation of the sensor package.
15 . A sensor package comprising: a first die having a capacitive sensor, the capacitive sensor including an active sensing portion and a shield surrounding the active sensing portion, the first die including a first bond pad electrically connected to the shield; a second die comprising: a voltage regulator configured to produce a shield voltage; a compensation circuit configured to produce a compensation signal, wherein a terminal of a coupling capacitor of the compensation circuit is connected to a terminal of the voltage regulator to produce the shield voltage; and a second bond pad electrically connected to the voltage regulator and the compensation circuit; an inter-chip bond wire electrically connecting the first and second bond pads, wherein the shield voltage is provided to the first die via the inter-chip bond wire to regulate the shield to the shield voltage; a package substrate having a package lead; and an off-chip bond wire electrically connected between a third bond pad of the second die and the package lead, wherein a communication signal is provided to the compensation circuit of the second die via the off-chip bond wire, the communication signal imposes an interference signal on the shield voltage, the interference signal further including a voltage which couples from the package lead of the sensor package through a parasitic capacitance and a bulk silicon of the first die to the shield which is located between the bulk silicon of the first die and the active sensing portion, the compensation signal is provided to the first die via the inter-chip bond wire, and the compensation signal is configured to reduce the interference signal on the shield voltage; and wherein the communication signal is a serial data acquisition signal external to the sensor package or serial clock signal originating external to the sensor package, the serial data acquisition signal and serial clock signal conforming to a data communication protocol.
16 . The sensor package of claim 15 wherein the communication signal comprises a digital communication signal from an electronic component external to the sensor package.
17 . The sensor package of claim 15 wherein the compensation circuit comprises: a logic invertor having an input and an output, the input being electrically connected to the third bond pad on the second die; and the coupling capacitor having a first terminal electrically connected to the output of the logic inverter and a second terminal electrically connected to the second bond pad.
18 . The sensor package of claim 17 wherein: the package substrate has a second package lead; and the sensor package further comprises a second off-chip bond wire electrically connected between a fourth bond pad on the second die and the second package lead, wherein a second communication signal is provided to the second die via the second off-chip bond wire, the second communication signal imposing a second interference signal on the shield voltage; and the compensation circuit further comprises: a second logic invertor having a second input and a second output, the second input being electrically connected to the fourth bond pad on the second die; and a second coupling capacitor having a third terminal electrically connected to the second output of the second logic inverter and a fourth terminal electrically connected to the second bond pad, wherein the second coupling capacitor is configured to produce a second compensation signal configured to reduce the second interference signal on the shield voltage.
19 . The sensor package of claim 15 wherein: the compensation circuit comprises a programmable capacitor array configured to provide a variable capacitance; and the second die further comprises processing circuitry coupled to the programmable capacitor array, the processing circuitry being configured to determine a capacitance value for the programmable capacitor array for producing the compensation signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the priority under 35 U.S.C. § 119 of European patent application no. 20306473.8, filed on 1 Dec. 2020 the contents of which are incorporated by reference herein. TECHNICAL FIELD OF THE INVENTION The present invention relates generally to sensor technologies. More specifically, the present invention relates to a sensor package with enhanced robustness against interference and a method of operation. BACKGROUND OF THE INVENTION A capacitive sensor device, such as a Coriolis-based gyroscope transducer, an accelerometer, a pressure sensor, and the like, outputs a capacitive signal indicative of measurements or other properties of the capacitive sensor device. Subsequent signal conditioning for such devices can be more efficient by first converting the capacitance signal to an analog voltage signal, processing the analog voltage signal, and converting the analog voltage signal to a digital representation of the signal. The market demands high performance sensors with good offset stability over temperature (TCO), low noise, and low power consumption. SUMMARY Aspects of the disclosure are defined in the accompanying claims. In a first aspect, there is provided a sensor package comprising a first die having a capacitive sensor, the capacitive sensor including an active sensing portion and a shield surrounding the active sensing portion, and a second die comprising a voltage regulator configured to produce a shield voltage and a compensation circuit configured to produce a compensation signal, the voltage regulator and the compensation circuit being electrically coupled to the shield, wherein the voltage regulator is configured to regulate the shield to the shield voltage, and the compensation signal produced by the compensation circuit is configured to reduce an interference signal on the shield voltage In a second aspect, there is provided in a sensor package that includes a first die and a second die, the first die having a capacitive sensor, the capacitive sensor including an active sensing portion and a shield surrounding the active sensing portion, and the second die comprising a voltage regulator and a compensation circuit electrically coupled to the shield, a method comprising providing a shield voltage from the voltage regulator to the shield to regulate the shield to the shield voltage, detecting an interference signal imposed on the shield voltage, producing a compensation signal at the compensation circuit in response to the interference signal, and providing the compensation signal from the compensation circuit to the shield to reduce an interference signal on the shield voltage. In a third aspect, there is provided a sensor package comprising: a first die having a capacitive sensor, the capacitive sensor including an active sensing portion and a shield surrounding the active sensing portion, the first die including a first bond pad electrically connected to the shield; a second die comprising a voltage regulator configured to produce a shield voltage, a compensation circuit configured to produce a compensation signal, and a second bond pad electrically connected to the voltage regulator and the compensation circuit. The sensor package further comprises: an inter-chip bond wire electrically connecting the first and second bond pads, wherein the shield voltage is provided to the first die via the inter-chip bond wire to regulate the shield to the shield voltage; a package substrate having a package lead; and an off-chip bond wire electrically connected between a third bond pad of the second die and the package lead, wherein a communication signal is provided to the second die via the off-chip bond wire, the communication signal imposes an interference signal on the shield voltage, the compensation signal is provided to the first die via the inter-chip bond wire, and the compensation signal is configured to reduce the interference signal on the shield voltage. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying figures in which like reference numerals refer to identical or functionally similar elements throughout the separate views, the figures are not necessarily drawn to scale, and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention. FIG. 1 shows a block diagram of a sensor package; FIG. 2 shows a simplified side sectional view of a sensor die of the sensor package of FIG. 1; FIG. 3 shows a side view of the sensor package; FIG. 4 shows a plan view of the sensor package; FIG. 5 shows a simplified plan view of the sensor package of FIG. 1 in accordance with an embodiment; FIG. 6 shows a flowchart of an interference compensation process in accordance with another embodiment; and FIG. 7 shows a flowchart of a calibration process in accordance with some