Multichannel Driver Circuit with Shared Capacitive Voltage Switching
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Solution Overview
Problem
Existing multichannel driver circuits face challenges with high voltage stresses and electromagnetic interference due to the use of high driving voltages, particularly when driving piezoelectric or ceramic transducers, which can lead to increased component costs and EMI.
Innovation Solution
A multichannel driver apparatus with a controller that manages multiple output stages, using shared capacitive voltage generators to vary switching voltages and duty cycles, minimizing the number of stages using high voltages simultaneously, and employing flying capacitor drivers to modulate output nodes between different voltages with controlled duty cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high driving voltages are used to drive piezoelectric or ceramic transducers, then the transducers can be driven effectively, but voltage stresses on components increase and EMI is generated
Solution Approach 1:
The patent divides the single high-voltage switching operation into multiple lower-voltage switching stages. The output node is switched between multiple voltage levels (e.g., +VS, 0V, -VS) rather than directly between high positive and negative voltages. This segmentation of the voltage transition reduces voltage stress on individual switching components and minimizes EMI generated during switching transitions.
Solution Approach 2:
The patent implements dynamic voltage generation where the switching voltages are not fixed but are generated dynamically based on the instantaneous signal levels. The capacitive voltage generator dynamically adjusts the voltage levels used for switching, allowing the driver to adapt to different operating conditions and minimize voltage stress while maintaining effective transducer driving.
2Object-affected harmful factors
If multiple different switching voltages are made available for each output stage, then multi-level switching can be implemented to reduce voltage stress and EMI, but device complexity increases
Solution Approach 1:
The patent merges the voltage generation function into a shared capacitive voltage generator that serves all output stages. Instead of each output stage having separate voltage generation circuitry, a single capacitive voltage generator provides the multi-level switching voltages to multiple channels. This sharing of the voltage generation function significantly reduces overall device complexity while still enabling multi-level switching operation in each channel.
Solution Approach 2:
The capacitive voltage generator is designed as a universal component that can provide multiple different voltage levels (+VS, 0V, -VS, and intermediate levels) to multiple output stages. This multi-functional voltage generator eliminates the need for separate voltage generation circuits in each channel, reducing complexity while enabling sophisticated multi-level switching operation across all channels.
3Device complexity
If a shared capacitive voltage generator is used to provide switching voltages to multiple output stages, then component costs are reduced, but the controller must manage coordination between stages to minimize simultaneous high-voltage usage
Solution Approach 1:
The controller monitors the operation status of multiple output stages and uses feedback information to dynamically adjust which stages receive high-voltage switching signals at any given time. By implementing feedback control, the system can coordinate the operation of shared voltage generators with multiple output stages, ensuring that not all stages simultaneously demand high-voltage operation, thereby reducing stress on the shared components and minimizing EMI.
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
This approach reduces voltage stresses on components and minimizes EMI by allowing flexible switching voltage configurations, optimizing power efficiency and reducing component costs.
Implementation Method 1
A first capacitive voltage generator is provided which outputs a first generated voltage
Implementation Method 2
employing flying capacitor drivers to modulate output nodes between different voltages with controlled duty cycles
Data Source
AI summary
This application relates to methods and apparatus for multichannel drivers for driving transducers in different channels. A multichannel driver has a plurality of output stages configured such that two output nodes can be modulated between selected switching voltages with a controlled duty cycle to generate a differential output signal across a respective transducer, each output stage being operable with different switching voltages in different modes of operation. A first set of two or more of the output stages are arranged to receive a voltage output by a capacitive voltage generator to use as a switching voltage. A controller is configured to control the mode of operation and duty-cycle of each of the output stages based on a respective input signal and also based on operation of the other output stages of the first set.