Tagged Questions

1
vote
1answer
61 views

Do I have to worry about backwards crosstalk with a 1 way bus?

I'm working on a DDR memory circuit, and I'm not sure how big an issue crosstalk is on the command/address bus. I've designed for crosstalk with the DQ/DQS and CLK lines because they are high ...
2
votes
3answers
320 views

The resistance between the 1.2V rail and GND is 40 Ohms, is it safe?

I have a power supply board that supplies a DSP, FPGA, CPLD and other components of a system. When I measure the resistance between power rails and GND using a multimeter I get the following readings: ...
10
votes
2answers
856 views

Why are vias placed this way on a PCB?

I used to check complex commercial PCBs specially those of graphics cards to see how professional PCB designers do their layout and learn from their techniques. When I checked the card shown below I ...
4
votes
2answers
281 views

Routing considerations of analog signals on twisted pairs

I'm designing a part of a system that will receive 4 analog signals carried on 4 twisted pair cables which are input to an ADC. These signals are low speed (probably in KHz) bipolar ranging from -10V ...
2
votes
2answers
357 views

How can I meet these PCB design conductivity/isolation requirements?

The specifications required are as follows: The resistance between ground pins on a connector and the case (chassis) ground should be less than 3 Ohms. The resistance between any other signal on the ...
3
votes
2answers
356 views

Why the measured voltage increases when I change ground reference?

The following image shows my connections: The grounds of all devices are connected to a common PCB. When I measure the 1.2V referenced to the ground on my PCB, it reads 1.201V which is great. But ...
2
votes
4answers
368 views

What's the Actual Speed in GHz of RapidIO or RocketIO serial interfaces?

When reading about high speed serial interfaces like RapidIO or RocketIO, I find data rates of 3.125 Gigabits/second and more. My question is: 3.125 Gb/s = ?? GHz What's the relation between Data ...
10
votes
2answers
669 views

How to transmit high current (2.6A) with low voltage (1.2V) for a long distance?

I want to supply a DSP with 1.2V. This DSP needs 2.6 Amps of current at full load. The minimum supply based on the electrical specs of this DSP is 1.16V, which means that the maximum voltage drop ...
6
votes
3answers
650 views

Want my PCB design to work right the first time!

Just finished a design of a 8-Layer PCB, the highest frequency is 125MHz. I want this design to work right the first time, how should I revise the design and what should I take care of? Something ...
3
votes
3answers
425 views

Best way to learn Signal Integrity

I am currently working on ECAD. Just to add more technical values to my work, I want to learn Signal Integrity and Thermal Analysis. What are the books,links you would suggest me to learn it? I am ...
7
votes
2answers
943 views

PCB routing: EMI and signal integrity, return current questions

If there's any EMI/SI lesson I've taken in, it's to minimize return loops as much as possible. You can work lots of EMI/SI guidelines from that one simple statement. However, not having or ever even ...