Pre-Charge Amplifier Circuit for Low Power Pulse Generation
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Solution Overview
Problem
Current pulse generation technologies for implantable pulse generators require high power consumption to achieve high frequency operation, which is detrimental to battery life, or they have poor slew rates that limit the frequency or duration of electrical stimulation pulses.
Innovation Solution
The implementation of a pre-charge period for each pulse using a low power amplifier with a programmable constant current stimulation pulse, facilitated by a universal custom output driver that includes a digital-to-analog converter and a scale circuit, allows for efficient high-frequency pulse generation with reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high power amplifiers are used to achieve high frequency operation, then slew rate is improved, but power consumption increases
Solution Approach 1:
The patent applies preliminary action by pre-charging the output capacitor to the target voltage level before the actual pulse is delivered. This pre-charge phase prepares the circuit in advance so that when the pulse is initiated, the amplifier does not need to rapidly charge the capacitor from zero, thereby reducing the slew rate requirement and allowing low power amplifiers to achieve high frequency operation.
2Use of energy by moving object
If low power amplifiers are used, then power consumption is reduced, but slew rate deteriorates
Solution Approach 1:
By pre-charging the output capacitor to the desired voltage level before pulse delivery, the circuit eliminates the need for rapid charging during the actual pulse. This preliminary action allows low power amplifiers with inherently slower slew rates to achieve high frequency operation, as the time-critical charging operation is performed during the pre-charge phase when power consumption is acceptable.
3Productivity
If high frequency pulse generation is implemented, then productivity is improved, but power consumption increases
Solution Approach 1:
The pre-charge mechanism performs the energy-intensive capacitor charging operation in advance, allowing subsequent pulses to be delivered rapidly without repeating the full charging cycle. This enables high frequency pulse generation (improved productivity) while keeping power consumption low, as the amplifier only needs to maintain the pre-charged state and deliver controlled discharge pulses.
Data Source
AI summary
A low power (and lower cost) implementation for amplifier used in delivering a stimulation pulse is provided according to embodiments through use of a pre-charge period for each pulse. For example, a voltage at a variable output terminal of a digital-to-analog converter is increased on the leading edge of PULSE and INVERTCLK signals to result in an output of an operational amplifier increasing to a predetermined voltage prior to output of a stimulation pulse, according to an embodiment. A shunt path may be implemented to shunt current away from a load during the pre-charge period.