Configurable Multiplexer Circuitry for Cellular Phone Field Testing
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Solution Overview
Problem
Conventional field testing systems for handheld electronic devices, such as cellular telephones, require dedicated circuitry and external connectors, which occupy significant space and increase the number of components, making them bulky and inefficient.
Innovation Solution
Incorporating configurable multiplexer circuitry and local bus power, allowing external access to shared buses between processors and providing power supply voltages locally, thus reducing the need for external pins and minimizing component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated circuitry and external connectors are used for field testing, then wireless performance testing capability is achieved, but device size and component count increase
Solution Approach 1:
The external connector is designed to serve dual purposes: supporting standard accessories during normal operation and enabling field testing connections when needed. The multiplexer circuitry allows the same physical connector to route signals to different internal destinations (baseband processor for testing, applications processor for normal use), eliminating the need for separate dedicated testing connectors and reducing overall device volume.
2Reliability
If dedicated circuitry and external connectors are used for field testing, then wireless performance testing capability is achieved, but number of components increases
Solution Approach 1:
The patent combines the field testing functionality with the existing accessory connector infrastructure. The multiplexer circuitry merges the testing signal path with the normal operation signal path, allowing a single connector to handle both purposes. This consolidation reduces the total component count by eliminating separate dedicated testing connectors and their associated isolation circuitry.
Solution Approach 2:
The external connector is designed to serve dual purposes: supporting standard accessories during normal operation and enabling field testing connections when needed. The multiplexer circuitry allows the same physical connector to route signals to different internal destinations (baseband processor for testing, applications processor for normal use), eliminating the need for separate dedicated testing connectors and reducing overall device volume.
3Ease of operation
If power supply voltages are provided through external pins, then external bus connectivity is achieved, but connector pin count increases
Solution Approach 1:
The power supply function is extracted from the external connector and relocated to an internal power management unit. The PMU generates the necessary power supply voltages (VDD, VDDIO, VDDCORE) internally and provides them to the baseband processor and multiplexer circuitry through internal power rails. This extraction eliminates the need for power supply pins in the external connector, freeing up pin count for data and control signals while maintaining full external bus connectivity.
Data Source
AI summary
A field testing system is provided that uses a personal computer tethered to an interface board. A cellular telephone plugs into the interface board during wireless field testing. The cellular telephone may include configurable multiplexer circuitry and power supply circuitry. During normal operation, the cellular telephone is configured so that its application processor is linked to its application processor and to an external bus. During field testing, the cellular telephone is configured to link the baseband unit to the external bus and the interface board. The baseband unit may support advanced communications busses (e.g., USB). To avoid consuming too many pins in the external bus between the interface board and the cellular telephone, power for the USB bus during field testing may be derived from a power management unit in the cellular telephone.