7 ms·

I assume for something like a phone these things are non-linear. going from 2 PCIe lanes (nand, radios) to 3 (another radio) may cause an SOC to jump from entr

by eigen 24d ago

I assume for something like a phone these things are non-linear. going from 2 PCIe lanes (nand, radios) to 3 (another radio) may cause an SOC to jump from entry-level to mid-level, larger PCB and increased layer count, more antenna for simultaneous use, etc. so its not just the cost of the chip but all the secondary effects.

Dylan16807 24d ago
A non-linear cost for a small fraction of the phone. A slightly larger PCB with two more layers is about twice the price for the PCB, more antennas is a couple dollars, a one lane PCIe switch is a few dollars if that's cheaper than upgrading your SOC. And if it shrinks your battery 10% you save money on that part. I blame niche-ness far more than the actual design and production costs. Edit: fixed the pcb wording
- eigen 24d ago
  > PCIe switch is a few dollars if that's cheaper than upgrading your SOC perhaps you're more familiar with these options than I am, but I see 4 lane PCIe switches are 10x10 mm and maybe they are a few dollars but take more board space, new/larger power supplies, etc so it seems that the costs are more than just a few dollar PCIe switch chip. not sure how many phone PCBs can handle additional 100 mm2 but definitely looking forward to learning more. [1] https://www.diodes.com/products/connectivity/pcie-packet-switchbridges/pcie-switch https://www.diodes.com/products/connectivity/pcie-packet-swi... add to the antennas are likely based on best/cheapest efficiency for the available area, then additional antenna would reduce the area for each and require more effort/cost.
  - justsomehnguy 24d ago
    > not sure how many phone PCBs can handle additional 100 mm2 You are clearly out of your league. Get some 20 y/o flip Motorola, disassemble it and think, think hard. No, 'PCIe switches' has nothing to do with the smartphones at all - so their PCB real estate do not indicate anything.
duskwuff 24d ago
In many phones, some of the radio hardware is integrated into the SoC. Adding a second, independent radio is a larger engineering task.

by eigen 24d ago

Dylan16807 24d ago

A non-linear cost for a small fraction of the phone. A slightly larger PCB with two more layers is about twice the price for the PCB, more antennas is a couple dollars, a one lane PCIe switch is a few dollars if that's cheaper than upgrading your SOC. And if it shrinks your battery 10% you save money on that part. I blame niche-ness far more than the actual design and production costs. Edit: fixed the pcb wording

eigen 24d ago
> PCIe switch is a few dollars if that's cheaper than upgrading your SOC perhaps you're more familiar with these options than I am, but I see 4 lane PCIe switches are 10x10 mm and maybe they are a few dollars but take more board space, new/larger power supplies, etc so it seems that the costs are more than just a few dollar PCIe switch chip. not sure how many phone PCBs can handle additional 100 mm2 but definitely looking forward to learning more. [1] https://www.diodes.com/products/connectivity/pcie-packet-switchbridges/pcie-switch https://www.diodes.com/products/connectivity/pcie-packet-swi... add to the antennas are likely based on best/cheapest efficiency for the available area, then additional antenna would reduce the area for each and require more effort/cost.
- justsomehnguy 24d ago
  > not sure how many phone PCBs can handle additional 100 mm2 You are clearly out of your league. Get some 20 y/o flip Motorola, disassemble it and think, think hard. No, 'PCIe switches' has nothing to do with the smartphones at all - so their PCB real estate do not indicate anything.

duskwuff 24d ago

In many phones, some of the radio hardware is integrated into the SoC. Adding a second, independent radio is a larger engineering task.