Sensor IC Voltage Artifact Suppression via Current Mirror
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Solution Overview
Problem
Sensor integrated circuits face challenges in maintaining accurate output and operational integrity in the presence of power disturbances such as voltage spikes, micro-cuts, and electrostatic discharges, which can lead to reset or loss of functionality.
Innovation Solution
A sensor integrated circuit with a high voltage bi-directional current source and disconnect switch, featuring a current mirror configuration that protects circuitry from voltage spikes and limits current conduction in both directions, including the use of MOSFET devices and a gate drive circuit to control the current flow and decouple energy storage from power pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a supply line filter (RC filter) is used to filter transient disturbances and store energy, then the sensor IC can withstand power disturbances, but the passive component size increases and supply bandwidth degradation occurs
Solution Approach 1:
The patent introduces an intermediary energy storage device (capacitor) coupled to the functional circuit through a current mirror, which acts as a mediator between the power supply and the sensor circuitry. This intermediary stores energy locally and releases it during power disturbances, protecting the sensor without requiring large external passive components.
Solution Approach 2:
The current mirror dynamically changes the electrical parameters (current flow, voltage levels) between the energy storage device and the functional circuit based on the power supply conditions. During normal operation, it regulates current; during disturbances, it switches states to maintain proper voltage levels, thereby protecting the sensor IC.
2Reliability
If a supply line filter (RC filter) is used to filter transient disturbances, then the sensor IC can withstand power disturbances, but the supply bandwidth degrades
Solution Approach 1:
The current mirror provides dynamic response to power supply conditions by actively switching its state based on voltage comparisons. Unlike a static RC filter that continuously attenuates signals, the current mirror only activates during disturbance conditions, maintaining full bandwidth during normal operation while providing protection when needed.
Solution Approach 2:
The energy storage device coupled through the current mirror acts as a dynamic intermediary that responds only to abnormal conditions. It does not continuously filter the supply signal like an RC filter, thus preserving bandwidth while still providing protection during transients and disturbances.
3Duration of action of stationary object
If the sensor IC restarts after a power disturbance, then operational continuity is restored, but the IC may restart in an improper state without proper reset control
Solution Approach 1:
The current mirror incorporates feedback mechanisms through voltage comparison circuits that monitor the power supply voltage and the energy storage device voltage. This feedback controls the switching transistors to ensure proper voltage levels are maintained, and provides feedback signals to control logic that manages the reset state, ensuring the IC restarts in the correct operational state.
Solution Approach 2:
The energy storage device is pre-charged during normal operation, and the current mirror is configured to maintain proper voltage levels before a disturbance occurs. When a disturbance happens, the pre-configured circuitry automatically activates to maintain proper operating conditions, ensuring the IC can restart correctly without requiring external intervention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses undesirable voltage artifacts and ensures the sensor IC can withstand power disturbances without resetting or losing output accuracy, maintaining operational integrity and accuracy even under adverse conditions.
Implementation Method 1
a current mirror having a current path in series between the power pin and the energy storage device and configured to control a current flow to the energy storage device and a current flow from the energy storage device
Implementation Method 2
The current mirror can include at least one MOSFET device. In some embodiments, the current mirror includes a pair of PMOS devices having a common gate connection and a common source connection
Implementation Method 3
Power from the external power supply can experience various disturbances that can adversely impact a sensor's ability to provide accurate output information. Power disturbances include, for example, interruptions and transients
Data Source
AI summary
Systems and methods described herein provide a sensor integrated circuit (IC) having a high voltage bi-directional current source and disconnect switch that are configured to suppress undesirable voltage artifacts. The sensor IC can include a power pin for coupling to an external power supply, a reference pin, and a functional circuit. The bi-directional current source can be disposed in a current path between the power pin and an energy storage device and be configured to control a current flow to the energy storage device and a current flow from the energy storage device.