IWR1443BOOST: which trace is 10 ohm trace in IWR1443Boost?

feng tang

Genius 3595 points

Part Number: IWR1443BOOST
Other Parts Discussed in Thread: IWR1443, IWR1642

Any one know which traces are 10 Ohm traces in IWR1443Boost layout?

Thanks!

over 7 years ago

0 Radio-Joe over 7 years ago

TI__Mastermind 37500 points

Hello Feng,

The net classes for IWR1443 or IWR1642 should be:

50 ohm Txn, Rxn - special GPCW, stripline and antenna with Ground pour

90 - 110 ohms - if you implemented the USB differential traces

100 ohm - differential pair, with exclusion from 1v8 signals for LVDS (if implemented)

There are no specific 10 ohm traces I can find listed. The hardware checklist attached, has some specific low impedance notes for the

power subsystem from PMIC to RF LDOs to mmwave sensor device for 1v8 and 1v3 volts. Please look at swra577 for PMIC with LC filters also.

I have included the hardware checklist,

Regards

Joe Quintal5226.HardwareDesignChecklist_V0p7fix_IWR1443_SWRR150.xlsx

0 feng tang over 7 years ago in reply to Radio-Joe

Genius 3595 points

properly just Typo error in your IWR1443boost layout fab note

0 feng tang over 7 years ago in reply to Radio-Joe

Genius 3595 points

Hi Joe,
Those differential pair are only around 70 ohm, could you double check on this?

0 Radio-Joe over 7 years ago in reply to feng tang

TI__Mastermind 37500 points

The standard LVDS impedance is 100 ohm line to line, 50 ohms line to GND. Depending on where you route the traces,
the stripline width, spacing can be changed (ie routing this on L6 would use an FR4 layer instead of the RF layer.
Regards,
Joe Quintal

0 feng tang over 7 years ago in reply to Radio-Joe

Genius 3595 points

The LVDS impedance only 68 ohm on RF layer if using dielectric 3.48, 67 ohm if using dielectric 3.66!!!

0 Radio-Joe over 7 years ago in reply to feng tang

TI__Mastermind 37500 points

Hello,
A 68 ohm impedance is normally line to GND. This would provide a 136 ohm line to line impedance. This would degrade the high frequency performance of the LVDS interface. So you can use it at a lower speed, (check if you are using LVDS), or modify the traces to 50 ohm line to GND and do the trace to trace width matching to have 100 ohms. The EVM does work with a 450Mhz clock, 900Mhz DDR data rate.
Regards,
Joe Quintal

0 feng tang over 7 years ago in reply to Radio-Joe

Genius 3595 points

No, since the traces sitting close to the ground (4mils), you can not use free space pair line calculation, that not give a correct signal traveling speed. I believe the impedance is not important if the impedance on the pair is matched, it does not cause a skew bigger than what it need.

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IWR1443BOOST: which trace is 10 ohm trace in IWR1443Boost?