Antenna Driver Circuit With Multiplexer Switching
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Solution Overview
Problem
Antenna driver circuits face limitations in efficiently generating and emitting low-frequency magnetic fields due to the number of driver channels, which can be costly to expand, especially in areas with damping or interference, while needing to comply with radio licensing and EMC guidelines.
Innovation Solution
The implementation of an antenna multiplexer circuit that allows flexible control of controllable switches, such as MOSFETs, arranged in anti-serial fashion to manage multiple antennas with independent control signals, enabling cost-effective extension of antenna channels and reducing time-critical switching, while providing effective common-mode emission suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the number of driver channels is increased to cover more antenna elements, then the coverage area and emission effectiveness are improved, but the cost and device complexity increase
Solution Approach 1:
Multiple antenna elements are merged into a single antenna multiplexer unit that shares common driver circuitry. The multiplexer combines several antenna elements (e.g., four elements) into one controllable output, allowing one driver channel to serve multiple antennas through time-multiplexed switching, thereby reducing the total number of driver channels needed while maintaining coverage area.
Solution Approach 2:
The antenna multiplexer provides multi-functionality by enabling a single driver channel to control multiple antenna elements sequentially. The same driver circuitry can serve different antenna elements at different time slots, making the driver channel universal rather than dedicated to a single antenna, thus reducing cost and complexity.
2Speed
If time-critical switching is implemented for antenna selection, then the emission response time is improved, but the device complexity and control difficulty increase
Solution Approach 1:
The antenna multiplexer employs periodic time-multiplexed switching where each antenna element is activated in sequential time slots. This periodic switching pattern simplifies control logic compared to arbitrary time-critical switching, as the switching sequence follows a regular, predictable pattern that can be generated with simpler control circuitry while still achieving fast emission response.
Solution Approach 2:
The switching sequence and antenna selection are predetermined and prepared in advance through a structured time-multiplexing scheme. The control system pre-establishes the switching pattern for multiple antenna elements, eliminating the need for complex real-time decision-making during emission, thus reducing control difficulty while maintaining fast response.
3Reliability
If common-mode emission suppression is implemented, then EMC compliance is improved, but the device complexity increases
Solution Approach 1:
The antenna multiplexer employs an asymmetric switching arrangement where antenna elements are connected in a non-symmetric configuration to the driver channel. This asymmetric topology inherently suppresses common-mode emissions by creating imbalance in the current paths, reducing radiated interference without requiring additional suppression circuitry, thus improving EMC compliance without significantly increasing device 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
This solution allows for a cost-effective expansion of antenna channels, optimizing the emission of low-frequency magnetic fields while ensuring compliance with regulatory guidelines, and enhances the current-carrying capacity and flexibility in antenna operation.
Implementation Method 1
Even after a quasi-resonant oscillation has been switched off by means of control signals before the end of a quasi-resonant oscillation by means of parasitic diodes, MOSFETs still conduct an antenna current until the oscillation energy of the oscillatory circuit is stored in the capacitors
Implementation Method 2
a quasi-resonant oscillation has been switched off by means of control signals before the end of a quasi-resonant oscillation
Implementation Method 3
A direct voltage level for suppression of common-mode emission can be connected to the two drain connections of controllable switches, which are arranged in an anti-serial fashion, as a result of which the direct voltage level only becomes effective if an antenna is selected for emission by means of the controllable switches
Data Source
AI summary
The present disclosure relates to an antenna driver circuit for an antenna associated with a motor vehicle. The antenna driver circuit may include at least one pair of output paths to at least one antenna for forming at least one oscillatory circuit composed of in each case an antenna and at least one capacitor, and a plurality of switches in the form of MOSFETs controlled by control signals in one respective oscillatory circuit with an antenna. In the respective oscillatory circuit, at least two controllable switches may be arranged in an anti-serial fashion with respect to one another in that their drain connections are connected together, and/or source connections of controllable switches are connected to one another via an antenna.