40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  SUS Lab eLog  Not logged in ELOG logo
Entry  Sat Oct 20 00:38:43 2018, Duo, HowTo, , DAC Noise monitor PCB layers 
    Reply  Tue Oct 23 00:57:13 2018, Duo, HowTo, , DAC Noise monitor PCB layers NoiseMonitor.pdf
       Reply  Wed Oct 24 15:01:50 2018, Duo, HowTo, , DAC Noise monitor PCB layers NoiseMonitor.pdf
          Reply  Wed Oct 24 21:55:45 2018, Duo, HowTo, , DAC Noise monitor PCB layers NoiseMonitor.pdf
Message ID: 1769     Entry time: Tue Oct 23 00:57:13 2018     In reply to: 1768     Reply to this: 1770
Author: Duo 
Type: HowTo 
Subject: DAC Noise monitor PCB layers 

I proceeded as described below. The routing is completed. All the signal routing is completed. One thing worries me is that I am afraid the signal ground and power ground is yet separated. I do have two internal planes for signal ground and power ground. Should they be connected to the same power input (so that they are just two planes with the same source)? Altium treats all the ground as one net GND. If the answer to the question is yes, I need to figure out how to get Altium separate them. In Altium, you can specifiy which net you connect to, but I did not figure out how to specify which layer. (Maybe I need to create a separated GND net, like PGND/SGND for that?) 

Here is a summary file with the schematics and PCB design: NoiseMonitor.pdf

Also, this is the link to the Wiki page, with more details about this work: https://wiki-40m.ligo.caltech.edu/Electronics/NoiseMonitor


Background: The design of the DAC noise monitor is in the PCB design stage - I am trying to put the circuit on the PCB board in Altium. We use three power voltages to drive the op amps in the circuit: -15 V. +15 V. We also need power ground and signal ground. This circuit is going to replace a part of a big PCB board with other existing circuits.

Question: What are the layers used by the existing design? The DAC noise monitor needs to fit with other parts, so they have to share the same layers. Is there a PCB layout file for the existing design?

In case of absence, I will start with a signal layer, a -15V power layer, a +15V power layer, a power ground, and a signal ground. I googled a bit and they say the cost will be high and five layers might be more than what we want. Besides, I am not sure about the sequence of the layers either. I will start with this in order to proceed in Altium before we figure out what we need to do:


Signal layer

+15V power

Power ground

Signal ground

-15V power


How much sense does it make?


Attachment 1: NoiseMonitor.pdf  544 kB  Uploaded Tue Oct 23 01:58:11 2018  | Hide | Hide all
NoiseMonitor.pdf NoiseMonitor.pdf NoiseMonitor.pdf
ELOG V3.1.3-