I am working with a client on a large project which requires a custom networking chip to be designed to solve the data transfer requirements within the project. The network is intended to send small packets a few inches from one PCB to another over a single twisted pair cable. We will be designing and specifying the network protocol, and another company will be responsible for the silicon implementation.
I estimate that 20Mbps data rate between nodes will easily cope with the amount of data that needs to be sent, with plenty of head room should the amount of data increase in the future.
The client is asking me why I am specifying only 20Mbps. Why not something like 1Gbps? Wouldn't that be better? Intuitively, I feel that cranking up the data rate massively beyond what would be needed is a bad idea. Initially, I thought that the cabling would need to be shielded (which I don't want), but looking at the Ethernet cable categories, I see that Gigabit Ethernet can run on Cat 6 cable, which doesn't need to be shielded.
- The project is desperately space constrained, and do we don't have room for things like magnetics, unless it's a very small component (0603 max).
- The cables need to be as slim and flexible as possible.
- The device will run from plug-in power, so there is no particular low-power requirement.
What are the problems, in terms of silicon design, cabling, and anything else, that may be faced at 1Gbps, that wouldn't be nearly as bad at 20Mbps? Should I go with my client's suggestion of implementing the network at 1Gbps, or should I insist on implementing only what is required?
We're under strict NDA, so I can't give too many details about our requirements. But please leave a comment if clarification is needed.