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Questions tagged [high-speed]

High-speed design deals with designing circuits which are working at high frequencies where side-effects like path inductance gain significant influence.

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125 views

Are there special rules for voltage division of a high speed clock?

High speed signals require special care in PCB layout to prevent high speed effects like ringing and overshoot. This obviously applies to clock signals as well. Provided that one has a high voltage ...
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1answer
46 views

Paralleling LVPECL outputs?

I have a pretty unusual application here, where I need to drive a fast differential signal fanning out into 8+ 100ohm transmission lines. The unusual part is this: the transmission lines must be ...
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1answer
61 views

noise of high speed serial link

I have an ADC module. The board contains sensitive (10-100MHz) analogue parts and a high speed serial link (Aurora). The link uses scrambling algorithm, and I can choose the bit-rate. (I have much ...
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0answers
34 views

Guidance for designing an experiment (high speed design)

so for a project I want to investigate simultaneous switching noise and how it cause changes in the source and ground voltage. I've been reading the High speed digital design book by johnson and ...
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1answer
41 views

what is simultaneous switching output noise?

Can someone explain to me what simultaneous switching output noise is (SSO) is it the same thing as simultaneous switching noise (SSN)? from what I understand when lots of pins are switching together ...
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1answer
65 views

PCB 6-layer stackup trace reference

I am designing a 6-layer board, with stackup like this: 1-TOP slow North/South 2-GND 3-Signal high speed East/West 4-Signal high speed North/South 5-VDD 6-Bottom slow East/West PCB plane spacing is: ...
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3answers
100 views

High voltage to low voltage in ps/nanosecond time (Zener/opamp?)

So I have a signal that goes from 0 to ~800volts in 30ns. I would like to use this signal to trigger a camera (input impedance of 50ohm) which takes a max of 10 volts and requires the rise time to be ...
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1answer
64 views

Problem with using USB HOST HS example

I am working with USB HS Host in MSC class with STM32F407 MCU. I want to write to the memory cells of a flash drive using usb. (It doesn't matter for me to write with a standard like FatFs, I just ...
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4answers
264 views

Do chips really need multiple values of decoupling capacitor in the same packages?

A similar question is asked here: "two bypass/decoupling capacitors" rule? But that question was about parallel bypass capacitors without mentioning package size (but the answers mostly ...
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1answer
52 views

How would I go about measuring an analog signal that has both positive and negative voltages on an arduino analog pin at a high sampling rate?

I have a signal that fluctuates between -70mV and 50mV. How would I get the arduino mega to read this on an analog pin at a high sampling rate? Ultimately I am trying to graph the data in real time so ...
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0answers
59 views

Problem with signal edge in schematics containing high speed IC switch

I am trying to design the following schematics: There are two kOhms resistance which are connected serially. One is load and another is device resistance. I need to apply the voltage in a the ...
0
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1answer
281 views

Does the motor speed change with the fully automatic star(wye)/delta starter?

At no load, I connected a 380V motor to start in the star connection for 5 seconds and thereafter change to the delta connection. I understand that torque will change since the current will change as ...
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4answers
2k views

Understanding the Maximum Speed that can be Transmitted over a Cable

I am trying to source a FFC/FPC cable for USB3.0 (+5gbps). This brought me to the question of signal transmission. I'm somewhat of a beginner in this topic. I know that you should match impedance on ...
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2answers
100 views

PCB - matching length - relevant in that case?

I am trying to design PCB with 85 MHz signal traces between IC and connector (the FPGA board will be connected to this connector). This connection contains 28 data signals and one clock signal. I ...
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2answers
119 views

High Speed Signal on Large Circular Ring

It's frequently communicated that when working with signals in the Ghz range, routing is extremely important to signal integrity. Pretty much any inclusion of unnecessary stubs is out of the question, ...
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2answers
104 views

High Bandwidth, High Voltage differential amplifier problems

I inherited a opamp measurement circuit that is supposed to be able to measure differential voltages of up to 1000 V with a bandwidth of 1 MHz and a protective impedance between the HV and SELV side. ...
2
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2answers
140 views

Best board-to-board low latency protocol/interface

I've been asking similar question which received some downvotes, so I'm reformulating my task (hopes this one gives more clarity). I'm planning to establish a high-speed (3 Gpbs full duplex) serial ...
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2answers
305 views

Bootstrapped Transimpedance Amplifier (TIA) - High Frequency Instability

I have constructed transimpedance amplifier in the hopes to achieve both high-gain (5kΩ) and high-bandwidth (50MHz) performance using the FGA21 photodiode, the OPA657 Op-Amp and the 2N2369 Transistor. ...
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1answer
76 views

USB Diff Pair used by 2 devices on PCB

My PMIC uses the DP/DN pair of USB type C to get the maximum current that it can draw to power up the circuit or charge the battery. The problem is that i don't have a hub and the signal from ...
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2answers
142 views

Is this LED slow, or am I measuring it incorrectly?

I am attempting to turn white light LEDs on and off at a very high speed. Here is a link to the LED being used. https://www.superbrightleds.com/moreinfo/through-hole/5mm-white-led-75-degree-viewing-...
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1answer
190 views

How does my crystal PCB layout look?

Please suggest if the layout is fine: it is 25MHz 3225 crystal. I maintained short traced for XIN and XOUT. I maintained a guard ring around the crystal. I have grounding in layer just below. the ...
0
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1answer
288 views

DDR3 SE signal, is 50Ohm impedance necessary?

I want to design a 6 layer PCB for an Allwinner H3 and DDR3, but the PCB workshop just have the stack-up shown in the image. With this stack-up, The calculation for striplines impedance is difficult. ...
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1answer
95 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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1answer
53 views

Jitter measurement in High speed serial link - Random jitter mean not 0

I made some jitter measurements of my high speed serial link yesterday. Now i'm analysing the jitter sources, and found out, my random jitter is often not around zero, most time about -1 .. -0.5ps. ...
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2answers
337 views

Gigabit Ethernet switch unused RGMII/MII/RMII interface

I am working on 5-port gigabit Ethernet switch based on Microchip KSZ9897. As the KSZ9897 is 7-port gigabit Ethernet switch (5 x 1000BASE-T/100BASE-TX/10BASE-Te IEEE 802.3 + 2 x RGMII/MII/RMI) and I ...
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2answers
278 views

USB 2.0 data lines swap suggestion

I need your advice regarding the USB 2.0 signals routing. When I reach the USB connectors, the data lines (D+ and D-) have to be swapped. I have two options there: 1) swap the lines using vias and go ...
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2answers
82 views

High-Speed electronics - Reflections in T-intersection

I'm currently attending a course on "experimental problem solving" and we just started talking about TDR (time domain reflectometry). I do understand that reflections occur whenever there is a change ...
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1answer
65 views

Multi-layer layout and return currents of high-speed signals

I am planning to use the following layer stackup for my 10-layer PCB: ...
6
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1answer
471 views

Why are most IR phototransistors slow?

Most NPN silicon phototransistors that I see (Everlight, Kingbright, etc.) have fairly poor rise and fall times, on the order of 10us. The best one I've seen so far is the QT Brightek QSD8T120B with ...
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2answers
809 views

RF PCB Design Basics - RF traces golden surroundings

In the answers to my previous question "RF Design Basics", there are explanations about the purpose of a golden ring around the PCB edge and around some parts (functional blocks) within the PCB. ...
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4answers
617 views

RF PCB Design Basics

I want to get some knowledge in RF PCB design. Therefore I have some questions about this, in order to make some clarification. What is the purpose of the golden ring around the PCB, often seen on RF ...
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1answer
138 views

Is there a rule for DDR4 CA signals reference plane?

I'd like to know if there is any rule for the reference plane of DDR4 CA signals in PCB layout. I saw some design guide which specify the reference plane to be VDDQ power plane for CA signals, but I'm ...
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1answer
205 views

USB 3.1 over PCIe board edge connector

I am designing a system with a carrier board that has all of active logic on one board and most connectors on a backplane board. The interface between the two boards is a x16 PCIe board edge connector....
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1answer
218 views

SiPM Array, High Speed Layout

I'm working on an prototype array of Silicon Photomultipliers using the Sensl MicroFJ-60035 TSV device. It's a small 6 mm by 6 mm square-shaped BGA photomultiplier. Think of a 6x6 BGA array with the ...
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2answers
731 views

high speed microcontroller - pc communication

I have a project where I have to sample a 4 bit bus every 100ns continuously for a data logging application (I need very low sampling jitter as well). I have a uC that can go up to 300MHz so speed isn'...
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1answer
75 views

HDMI Adaptor Board - Blank Screen [not working]

I have a Raspberry Pi and a custom HDMI screen board stacked as shown in the photo here. If I use a 'standard' HDMI lead then I have no problem. However, due to the form factor a lead does not suit ...
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3answers
226 views

Increasing Speed of Bootstrapped Amplifier

I am trying to implement the design described here to create an amplifier circuit that will amplify a 10MHz, 24Vpp signal to 120Vpp. I am using the THS3062 op-amp, and originally I was looking at ...
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3answers
236 views

Series Termination Resistors Sharing a Common Point

Suppose I have a high speed digital signal (represented as a square wave) that splits off and is shared between two subsequent inputs stages (represented as MOSFETs). Is it better to have two series ...
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1answer
532 views

AC coupling caps on USB interface [duplicate]

Does anyone know why AC coupling caps should be implemented in USB3 interface while it's not required in USB1/2? Anything to do with transmition speed, encode method?
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1answer
76 views

High speed IR connection [closed]

Are there any IR receivers/transmitters with speed higher then 4Mbps? As I found most parts are limited to 4Mbps, like LT1328 (photodiode receiver) and TFBS6711 (infrared transceiver)
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0answers
191 views

High speed, TTL compatible, high-side switch IC

I like full integrated automotive high-side switches, such as the ISP452. I like them because of their simplicity, making extremely easy driving grounded loads at standard voltages (12V or 24V) with ...
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3answers
1k views

More Vdd than Vss Pins

I am currently working on my first microcontroller hardware design; I had a microcontroller class in college, but it focused on the software side of things, and used a pre-made development board (for ...
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5answers
2k views

Why doesn't controlled impedance depend on track length? [duplicate]

High speed design noob here. Resistance increases as wire gets longer, but I found in saturn pcb calculator the impedance depends only on track geometry and distance from plane. Say for DDR3 single ...
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1answer
266 views

Minimum Rise Time for Microcontroller (STM32F769IIT6)

I'm trying to do some crosstalk calculations between signals and I'm trying to find the minimum rise times for the STM32F768IIT6 - all I see are the maximum rise/fall times for the specified test ...
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2answers
2k views

Differential Pair Length Matching for DP83848I

I'm looking in the datasheet and layout guide of the DP838481 but I can't seem to find where it talks about length matching for the RX and TX differential pairs. It only mentions length matching for ...
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2answers
1k views

Quad SPI PCB layout

I am trying to make a good layout for the Quad SPI NOR flash memory MT25QL256ABA1EW9-0SIT with the STM32 MCU. My problem is that I find the memory chip pinout quite inconvenient. I have managed to ...
2
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2answers
168 views

The “Impedance” Equation

In "Right the first time" by Lee W. Ritchey, he says "The impedance will be the same whether the frequency of the EM energy is 1 MHz or 1 GHz. This holds true so long as none of the three variables ...
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1answer
332 views

are there any differences between referencing signal to VCC or GND planes?

In my first high-speed PCB design, I have an LPDDR3 RAM and my PCB have 6 layers with the below sequence: 1-Signal 2-GND_Plane 3-Signal 4-Signal 5-VCC_Plane 6-Signal the region between the SOC ...
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1answer
431 views

LVDS cable between a camera and a FPGA

I'm using a development kit which is made a camera board and a FPGA board. So far, in this kit, the camera board is directly plugged onto the FPGA board. I have tested a new code for my FPGA. ...
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1answer
492 views

How to calculate Impedance of Edge Coupled Stripline Coplanar Waveguide

I have some questions about adding copper pour on signal layers with high-speed differential pairs traces. I am routing my HDMI diff pair traces on an inner layer. because we have been having some ...