Modular Differential Signal Multiplexers for Multi-Channel TIA Outputs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional commercial-off-the-shelf transimpedance amplifiers (TIAs) in LIDAR systems do not facilitate the construction of multi-channel systems easily, as they require additional analog switches and gain blocks that compromise bandwidth and dynamic range, and are not modular, preventing the multiplexing of any desired number of TIA outputs to a single analog-to-digital converter (ADC).
Innovation Solution
The development of modular analog signal multiplexers that allow differential input signals from multiple TIAs to be multiplexed into a single ADC, using a switch arrangement and uncommitted load resistors to enable modular, extendable output stages with minimal additional components, maintaining low noise and high bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional COTS TIAs are used to build multi-channel systems, then system functionality is achieved, but additional analog switches and gain blocks are required which compromise bandwidth and dynamic range
Solution Approach 1:
The patent merges multiple TIA output channels into a single ADC input by implementing a multiplexer circuit that combines N TIA outputs. This consolidation eliminates the need for separate ADCs for each channel and removes the requirement for additional analog switches and gain blocks in the signal path, thereby maintaining bandwidth and dynamic range while achieving multi-channel functionality.
Solution Approach 2:
The multiplexer circuit is designed with universal functionality to handle N different TIA output channels and route them to a single ADC. This multi-functional design allows the same circuit architecture to serve multiple channels simultaneously, providing adaptability for various channel configurations without requiring channel-specific additional components.
2Reliability
If conventional COTS TIAs are used, then individual TIA functionality is maintained, but they are not modular and do not allow multiplexing of any desired number of TIA outputs to a single ADC
Solution Approach 1:
The system is segmented into modular components where N independent TIA channels can be individually configured and then multiplexed. Each TIA maintains its individual functionality while the multiplexer provides modular integration capability, allowing any desired number of channels to be combined according to system requirements without compromising individual TIA performance.
3Productivity
If multiple ADCs are used for each TIA channel, then each channel has dedicated conversion capability, but board area, power dissipation, and bill of materials increase
Solution Approach 1:
The patent merges N separate ADC functions into a single ADC by implementing a multiplexer that time-division multiplexes N TIA output channels to the single ADC input. This consolidation reduces board area from N separate ADCs to one ADC, reduces power dissipation proportionally, and reduces the bill of materials while maintaining the signal conversion capability for all channels through sequential processing.
4Adaptability or versatility
If additional analog switches and gain blocks are placed in the signal path, then multi-channel multiplexing is enabled, but bandwidth and dynamic range are compromised
Solution Approach 1:
The patent extracts and eliminates the need for additional analog switches and gain blocks from the signal path by implementing a multiplexer design that directly interfaces N TIA outputs to a single ADC. This extraction removes the harmful components that would compromise bandwidth and dynamic range while preserving the essential multiplexing functionality through a streamlined signal path.
Data Source
AI summary
An example analog signal multiplexer includes two differential input signal ports for receiving a first and a second differential input signals, IN1 and IN2. The multiplexer further includes a differential output signal port with two output terminals OUT+ and OUT−, for outputting a signal based on one or more of the input signals IN1 and IN2. Furthermore, the multiplexer includes a pair of load elements, and an additional differential output signal port that has two output terminals TERM+ and TERM−. The load elements are not coupled directly to the output terminals OUT+ and OUT−, but, rather, are coupled to the output terminals of the additional output signal port, TERM+ and TERM−, enabling a modular approach where multiple instances of the multiplexer may be combined on an “as-needed” basis to realize multiplexing between a larger number of differential inputs that a single multiplexer would allow.