Switched Driver Circuit With Capacitive Boosting for Lower Ripple
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Solution Overview
Problem
Conventional driver circuits for transducers often require large inductance to prevent saturation under peak current conditions, which can be undesirable due to size constraints and increased ripple in switching amplifiers.
Innovation Solution
A driver circuit with a network of switching paths and capacitors that allows selective connection and boosting of input voltages, enabling operation in multiple modes with reduced voltage differences between switching voltages, thereby reducing ripple and allowing smaller inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an inductor is included as a separate component in the output path to suppress switching ripple, then ripple suppression is improved, but the inductance required becomes relatively large which increases device size and complexity
Solution Approach 1:
The patent extracts the inductance function from a separate physical inductor component and implements it using the inherent inductance of the voice coil in piezoelectric or ceramic transducers. This eliminates the need for an additional discrete inductor component while maintaining the ripple suppression function.
Solution Approach 2:
The voice coil of the transducer serves dual purposes: as the actuator element for sound generation and as the inductor for ripple suppression. This multi-functional approach eliminates the need for a dedicated inductor component.
2Reliability
If the inductance is increased to allow peak current without saturation, then current handling capability is improved, but the inductor size becomes larger which is undesirable
Solution Approach 1:
The voice coil serves as both the transducer actuator and the current-handling inductor, eliminating the need for a separate inductor that would increase device size.
Solution Approach 2:
The inductance function is extracted from a separate inductor component and assigned to the voice coil, which already exists in the transducer structure, thereby avoiding additional size increase.
3Use of energy by moving object
If a switching amplifier stage is used to generate driving signals, then power efficiency is improved, but switching ripple is generated which requires additional ripple suppression components
Solution Approach 1:
The switching ripple generated by the efficient switching amplifier is converted into a beneficial effect by using the voice coil's inductance to suppress it, thereby maintaining power efficiency while eliminating the need for additional ripple suppression components.
Solution Approach 2:
The voice coil performs multiple functions including sound generation and ripple suppression, allowing the system to maintain high power efficiency without requiring separate ripple suppression components that would add complexity.
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 reduces the maximum voltage ripple and allows for a given output voltage range with lower input voltage requirements, improving efficiency and reducing the need for large inductance.
Implementation Method 1
each of the first capacitor and the second capacitor can be selectively connected in series between the first and second input nodes to be charged to the input voltage
Data Source
AI summary
The application describes a switched driver (401) for outputting a drive signal at an output node (402) to drive a load such as a transducer. The driver receives respective high-side and low-side voltages (VinH, VinL) defining an input voltage at first and second input nodes and has connections for first and second capacitors (403H, 403L). A network of switching paths is configured such that each of the first and second capacitors can be selectively charged to the input voltage, the first input node can be selectively coupled to a first node (N1) by a path that include or bypass the first capacitor, and the second input node can be selectively coupled to a second node (N2) by a path that includes or bypasses the second capacitor. The output node (402) can be switched between two switching voltages at the first or second nodes. The driver is selectively operable in different operating modes, where the switching voltages are different in each of said modes.