FPAA CAB Architecture With Switch-Less Routing for Bandwidth
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Solution Overview
Problem
Existing field programmable analog arrays (FPAA) face challenges in achieving high configurability and bandwidth due to the use of routing switches, which introduce significant bandwidth limitations and reduce programmability.
Innovation Solution
A 6×6 matrix of configurable analog blocks (CABs) with a switch-less routing network between CABs, combined with a global feedback network, allowing for both differential and single-ended mode circuit configurations, and a synthesis methodology for rapid circuit implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If routing switches are used to provide connectivity between CABs, then programmability is improved, but bandwidth is limited
Solution Approach 1:
The routing network is segmented into two distinct types: switch-based routing within individual CABs for fine-grained programmability, and switch-less routing between CABs for high-bandwidth communication. This segmentation allows each routing type to optimize for its specific function without compromising the other.
Solution Approach 2:
Different routing strategies are applied to different spatial locations and functional requirements within the FPAA. Switch-based routing is used locally within CABs where programmability is critical, while switch-less routing is used for global inter-CAB connections where bandwidth is paramount.
2Speed
If switch-less routing is used between CABs, then bandwidth is improved, but programmability is reduced
Solution Approach 1:
The routing functionality is divided between two mechanisms: switch-less global interconnects provide the high-bandwidth backbone, while embedded switches within each CAB provide the programmable configuration layer. This segmentation ensures both bandwidth and programmability are achieved.
Solution Approach 2:
The CAB acts as an intermediary that combines both routing approaches. The switch-less network provides direct high-speed paths between CABs, while the embedded switches within each CAB mediate the connection to provide programmability and interface with the global network.
3Ease of manufacture
If fixed analog subcircuits are used in CABs, then manufacturing complexity is reduced, but configurability is limited
Solution Approach 1:
A universal set of reconfigurable building blocks is provided within each CAB that can be programmed to implement multiple different analog functions. The same physical hardware structure serves multiple purposes through programmable interconnections and parameter control, eliminating the need for different fixed circuits for each function.
Solution Approach 2:
The CAB architecture employs dynamic reconfiguration capabilities where circuit parameters and interconnections can be changed after manufacturing. This allows the same fixed physical structure to adapt to different functional requirements through programmable control, achieving high configurability without increasing manufacturing complexity.
Data Source
AI summary
A field-programmable analog array (FPAA) fabric includes a 6×6 matrix of configurable analog blocks (CABs). The implementation of programmable CABs eliminates the use of fixed analog subcircuits. A unique routing strategy is developed within the CAB units that supports both differential and single-ended mode circuit configurations. The bandwidth limitation due to the routing switches of each individual CAB unit is compensated for through the use of a switch-less routing network between CABs. Algorithms and methodologies facilitate rapid implementation of analog circuits on the FPAA. The proposed FPAA fabric provides high operating speeds as compared to existing FPAA topologies, while providing greater configuration in the CAB units as compared to switch-less FPAA. The FPAA core includes 498 programming switches and 14 global switchless interconnects, while occupying an area of 0.1 mm2 in a 65 nm CMOS process.