Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [serpentine-trace]

meandering traces so designed in order to match the propagation times of two or more signals on a PCB. Also called meandering or trombone traces in the literature; less formally called wiggle or squiggle traces.

13 questions
43
votes
2 answers

Why wiggle nearby tracks on a PCB?

I've been reading an article (TheMagPi eMagazine) relating to the Raspberry Pi; "An ARM GNU/Linux box for $25." In the article, page 17 at the bottom it shows an area on the Pi where a track zigzags next to a straight one with the explanation…
George Duckett
  • 535
  • 5
  • 10
39
votes
2 answers

Purpose of "wave shaped" PCB traces

On some PCB designs, specific traces are routed in curious ways. This probably has to do with high frequency design considerations and general signal behavior that I am not familiar with. Let's take this PCB (somewhere from the web) as an example.…
Rev
  • 10,017
  • 7
  • 40
  • 77
23
votes
1 answer

What is this squiggly trace for?

It's on pin 14, which is the master clock input (MCLK) of a WM8761: Low cost stereo DAC. I'm guessing it's meant to act as a small inductor? But why would you want that on a clock input?
endolith
  • 28,494
  • 23
  • 117
  • 181
10
votes
4 answers

Question about trace length matching patterns for high speed signals

A colleague and I had a discussion and a disagreement about the different ways high speed signals can be length-matched. We were going with an example of a DDR3 layout. All the signals in the picture below are DDR3 data signals, so they are very…
SomethingBetter
  • 2,260
  • 7
  • 26
  • 33
9
votes
2 answers

Length Matching Differential Pairs

I am routing a PCB with an Ethernet connection and I am having a bit of trouble deciding on how best to route the TX and RX differential pairs. I have done the impedance calculations to figure out the track geometry needed for 100 ohm differential…
IgorEE
  • 513
  • 1
  • 6
  • 21
6
votes
2 answers

Using a PCB trace as a heater / Hilbert Curves

I'm considering making a PCB to use as a heater for a 3d printer bed. This has been common practice for ~10 years (https://www.thingiverse.com/thing:3919). I was playing around with KiCad and python, and made a PCB trace that could (in theory) be…
Raph
  • 63
  • 4
6
votes
2 answers

How should I lay out timing matched traces?

Two nets on my PCB need to be matched to within 100 mil, preferably 50 mil. Currently I am doing this (see below); they are matched to about 10 mil. However I am worried about whether I am Doing It Right (TM). Is there a better way? I am using…
Thomas O
  • 31,546
  • 57
  • 182
  • 320
4
votes
2 answers

Why do serpentine traces (supposedly) entail decreased ESD immunity?

In an Intel guideline for their 82579 Gigabit Ethernet controller I've read (p. 18) that a side effect of using serpentine traces on the MDI (which carries the actual Ethernet signals) leads to decreased ESD immunity. I'm fairly familiar with the…
Fizz
  • 14,355
  • 2
  • 43
  • 97
2
votes
1 answer

Differential Pair Length Matching

I am routing a 16 bit ADC chip, the LTC2217 (datasheet) to FPGA. Each bit is an LVDS pair and I know +/- of the pair should be the same length but what about from pair to pair? I have 2 of these chips, 18 pairs, if you include OF and CLK, 36 pairs…
TylerM
  • 23
  • 3
2
votes
1 answer

Serpentine PCB heater size calculation

So, I'm kinda new to the field and the time has come to design my first PCB heater. The main concept is to drive it using a Raspberry Pi and a temperature sensor as feedback. Here is the whole procedure I followed in steps. Since my AC/DC adapter…
J. Doe
  • 121
  • 3
2
votes
3 answers

differential pair impedance and length matching

I'm designing a high speed circuit (MIPI-DSI) so I have to carefully layout the tracks. Correct track impedance is the first point usually made in various online sources I've found on the subject, so I tried to get the microstrip impedance…
Genoil
  • 258
  • 2
  • 13
2
votes
2 answers

Designing PCB for fast data

I'm trying to connect multiple components (same components) to an FPGA output. The FPGA runs at 30Mhz and transmitting both a clock and data on lines connected to these similar components. Each component is located in a different distance from the…
Gilad
  • 2,087
  • 1
  • 21
  • 25
1
vote
1 answer

Why do some PCBs have zig-zag tracks?

I've seen many boads with weird zig-zag shaped tracks just like the one below. Why are they designed like that?
PDuarte
  • 1,399
  • 1
  • 12
  • 16