Implantable Stimulator Voltage Regulator With Transient-Filtered Feedback
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Solution Overview
Problem
Existing voltage regulator circuits in implantable medical devices (IMDs) are destabilized by current transients from downstream circuits like boosting circuits, leading to unstable output voltages that affect the operation of stimulation circuitry.
Innovation Solution
An improved regulator circuit with current mirror and feedback mechanisms stabilizes output voltage by filtering transient currents, using a current mirror to scale and filter feedback signals, ensuring stable operation even with extreme current fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a voltage regulator circuit is used to power downstream circuits, then the output voltage should be stable, but current transients from downstream circuits destabilize the output voltage
Solution Approach 1:
The patent introduces an intermediary feedback path that samples the output current and feeds it back to the error amplifier. This intermediary signal allows the regulator to detect and respond to current transients before they cause significant voltage instability, effectively mediating between the downstream circuits and the voltage regulation mechanism.
Solution Approach 2:
The patent implements a feedback mechanism where a portion of the output current is sampled and fed back to the error amplifier. This feedback loop enables the regulator to dynamically adjust its operation in response to current transients, maintaining stable output voltage despite variations in downstream circuit current demands.
2Power
If a boosting circuit is used to create compliance voltage, then high voltage output is achieved, but current transients are generated that destabilize the regulator
Solution Approach 1:
The patent takes preliminary action by sampling the output current and preparing the feedback signal before the transient effects fully manifest. The error amplifier receives advance notice of current changes through the feedback path, allowing it to pre-adjust the regulator output to compensate for upcoming transients from the boosting circuit.
Solution Approach 2:
The feedback mechanism continuously monitors the output current from the boosting circuit and adjusts the regulator operation accordingly. This closed-loop control allows the system to maintain stability even when the boosting circuit generates significant current transients during voltage regulation.
3Stability of the object's composition
If current mirror circuitry is added to scale feedback signals, then transient filtering is improved, but device complexity increases
Solution Approach 1:
The patent uses current mirror circuitry to create a copied version of the output current signal. This copy is then fed back to the error amplifier, allowing the original current signal to continue its primary function while the copied signal provides transient filtering information. This copying approach enables improved transient response without significantly complicating the overall circuit architecture.
Data Source
AI summary
Regulator circuitry for producing a regulated output voltage in an implantable stimulation device and associated methods are disclosed. The regulator circuitry is particularly useful where a load current drawn from the output voltage involves transients, such as occurs when the output voltage is used to power a charge pump that creates a higher power supply voltage (e.g., a compliance voltage) in the device. The output current is sampled and downscaled in the regulator, and is further mirrored and filtered. This filtered current provides a control voltage in which transients are minimized and smoothed, and which is more suitable for use as a feedback voltage when producing the output voltage.