Questions tagged [skew]

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How much skew correction can typically be applied to DQS during DDR4 link training?

My understanding of the DDR4 calibration process is that DQS is derived from a common clock with a PLL, then passed through a DLL to apply deskew such that DQS and CK edges arrive in sync. Is there ...
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LVDS: Higher skew deviation or termination resistors as close as possible to the IC

I am designing a pcb with a video interface which runs lvds. LVDS has termination resistors and the datasheet states to have them put as close to the IC pins as possible. It's not 4k, but close to ...
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1 vote
1 answer
468 views

PCIE Gen 2 Intra-Pair Skew

I am about to make a revision of a PCB that has 60 mills of Intra-Pair Skew in PCI-E (Gen 2) RX differential pair: Considering the capacitors the skew is ~50 mills: this is the relevant part of the ...
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1 vote
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Lattice FPGAs -- How to control skew on signals routed to IO pins?

Working with: Lattice XP2-30 or XP2-40 Tentatively a BGA484; almost certainly some BGA 1mm-pitch package Synplify PRO, with SystemVerilog Skill level: Beginner / early-intermediate. If I have a ...
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  • 1,886
0 votes
2 answers
703 views

Calculating Phase angle from instantaneous voltage

For background info I am an EE/CE that is 10 years out of school and has since worked writing firmware and dealt mostly with digital communications and signals, so now I am having to reach back to my (...
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1 answer
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Circuit not working: Differential impedance, or skew, or a different problem responsible?

For a hobby project, I am designing a circuit that converts displayport to APIX2, which is a serializer protocol used in cars' infotainment systems, mostly BMW. This is done by an INAP375T IC, APIX is ...
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1 vote
1 answer
137 views

Which is better, less crosstalk or less skew?

I'm designing a board that has a LVDS 2.5V interface with 30 lanes clocked at 600MHz and DDR. This is going from one chip to another chip which could be placed right next to it, there are no other ...
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5 votes
2 answers
906 views

Routing USB, DVI and Ethernet signals on a large PCB vs using long cables

Properly routing USB, DVI and Ethernet signals over long distances (30 to 40 cm) on a PCB seems to be relatively challenging (skew, characteristic impedance, cross-talk, etc.). Yet using the standard ...
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  • 167
1 vote
1 answer
426 views

Skew angle in 3-phase AC induction outer rotor motor

I am working on a motor like the above stated. I have 3-phase winding on a 24 slot stator. I am now designing the rotor part. What skew angle should i use for a very smooth rotational torque? Is there ...
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  • 21
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2k views

Set the threshold voltage of CMOS inverter to VDD/2 for both rising and falling edge: possible?

Using 0.35u technology (VDD= 3.3v, Vt=0.7, Tox = 0.7 nm), I am trying to set the threshold voltage of an inverter to VDD/2. If I set the width ratio of PMOS/NMOS to 5 (means the Width of PMOS would ...
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  • 832
2 votes
1 answer
752 views

How to create a triple redundant clock tree in FPGA manually?

I am exploring a range of techniques to implement TMR clock trees as part of a global TMR design (all resources including i/o pins, clock trees, reset trees, logic and registers are implemented with ...
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2 votes
2 answers
827 views

Combinational logic delay is greater than clock period

Suppose you have a combinational circuit between two registers driven by a clock. What will you do if the delay of the combinational circuit is greater than your clock signal? (You can’t resize the ...
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  • 127
4 votes
1 answer
889 views

Distributing a 40MHz clock to several PCBs

I need to run four PCBs with a very accurately synchronised clock. The source clock is 40MHz, but each PCB contains a 1GHz PLL, and will be timing events in the analogue domain with a final ...
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