Pulse-density modulation to synthesize stimulation waveforms on an implantable device
Inventors
Perryman, Laura Tyler • Bakkaloglu, Bertan • Andresen, Chad David
Assignees
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Publication Number
US-10646164-B1
Publication Date
2020-05-12
Expiration Date
Abstract
A wirelessly powered implantable stimulator device includes one or more antenna configured to receive an input signal non-inductively from an external antenna, the input signal containing (i) electrical energy to operate the implantable stimulator device and (ii) configuration data according to which a pulse-density modulation (PDM) encoded stimulus waveform signal is retrieved to synthesize a desired stimulation waveform; a circuit coupled to the one or more antenna; and one or more electrodes coupled to the circuit and configured to apply the desired stimulation waveform to neural tissue, wherein the circuit is configured to: rectify the input signal received at the one or more antennas non-inductively; extract the electrical energy and the configuration data from the input signal; and in accordance with the extracted configuration data, retrieve the pulse-density modulation (PDM) signal to synthesize the desired stimulation waveform therefrom.
Core Innovation
The invention describes a wirelessly powered implantable neural stimulator that non-inductively receives an input signal through a non-inductive coupling from an external controller. The input signal contains electrical energy and configuration data, and the configuration data includes parameters for generating a specific stimulus waveform for application to neural tissue via one or more electrodes.
A circuit coupled to one or more antennas rectifies the input signal and extracts the electrical energy and the configuration data from the rectified input signal. The circuit includes a memory device storing a digital representation of a PDM encoded signal for generating the specific stimulus waveform, and includes a clock and an oscillator device. Based on the parameters in the extracted configuration data, the circuit selects the digital representation stored in memory and controls the oscillator device so the clock clocks the PDM encoded signal while converting the digital representation using the extracted electrical energy to generate the specific stimulus waveform.
The disclosed approach uses a PDM encoded stimulus waveform stored as a digital representation, described as a bit stream and converted by serially shifting out and reconstructing using integrate-and-hold/low-pass reconstruction. The configuration data parameterization includes pulse duration and repetition rate controlled by oscillator clocking behavior, amplitude control, polarity information for electrode polarity state, and multi-waveform selection via multiplexing device operation across multiple memory devices.
Additional disclosed embodiments include optional DC offset sensing and a DC servo loop to correct duty-cycle/DC offset in a full-bridge PDM driver. In these embodiments, a sensing subsystem provides information of a sensed DC offset that is integrated and used to drive the H bridge electrode driver, while the system operates passively from extracted electrical energy and uses the extracted configuration data to set the stimulus waveform parameters and electrode polarity.
Claims Coverage
The independent claim is clm-00001. The listed dependent claims refine the independent claim by adding internal waveform-storage and serialization features, multi-waveform selection, polarity control, oscillator parameterization, and DC offset sensing with an H-bridge electrode driver.
Wireless non-inductive energy and configuration input
One or more antennas receive an input signal through a non-inductive coupling from an external controller, where the input signal contains electrical energy and configuration data including parameters for generating a specific stimulus waveform.
Rectification and extraction of electrical energy and configuration data
The circuit is configured to rectify the input signal received through the non-inductive coupling, to extract the electrical energy and the configuration data from the rectified input signal.
Memory-stored PDM digital representation with oscillator/clock conversion
A circuit includes a memory device storing a digital representation of a PDM encoded signal for generating the specific stimulus waveform, and includes a clock, an oscillator device, and an H bridge electrode driver, where the circuit selects the digital representation based on extracted configuration data and controls the oscillator device to clock and convert the PDM encoded signal using extracted electrical energy such that the specific stimulus waveform is generated by the H bridge electrode driver.
Serial bit-stream PDM reconstruction for waveform generation
The memory device stores the digital representation of the PDM encoded signal as a bit stream, and the specific stimulus waveform is generated by serially shifting out the bit stream using the oscillator device and the circuit clock.
Multiplexed selection among multiple stored PDM waveforms
The circuit further comprises a multiplexing device and multiple memory devices that each store a PDM encoded stimulus waveform signal, and the multiplexing device selects a particular PDM encoded stimulus waveform signal.
Polarity-state control from polarity information
The configuration data further comprises polarity information, and the circuit is configured to set a polarity state for each of the one or more electrodes according to the polarity information.
Pulse duration and repetition rate controlled via oscillator clocking
The parameters for generating the specific stimulus waveform comprise a pulse duration and a repetition rate to control the oscillator device so the waveform is generated according to the pulse duration and repetition rate.
H-bridge electrode driver driven using sensed DC offset information
A sensor device drives the H bridge electrode driver using information of the DC offset sensed and integrated.
Coverage centers on a non-inductively coupled wireless input containing electrical energy and configuration data, rectification with extraction of those inputs, selection of a memory-stored PDM encoded digital representation, and oscillator and clock controlled conversion to generate a specific stimulus waveform via an H bridge electrode driver. The dependent claims further specify bit-stream storage and serial shifting, multiplexed selection among multiple PDM waveforms, electrode polarity state selection, pulse duration and repetition-rate parameterization, and H-bridge drive adjustment using sensed and integrated DC offset information.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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