Digital Logic Circuits Negative Regulators don't need to have a lot of current output

[Billy Mayo]

I have noticed at my work that the digital logic circuits negative voltage regulators are 1/2 the currents output of the Positive voltage regulators

My manager said that the negative voltage regulators don't need a lot of current output because it's just a reference to turn on the OP amps and IC chips. For logic circuits it only uses the Positive swing/cycle mostly so you have to have a 1 amp current output on the Positive Voltage Regulator.

So the Negative Voltage Regulator is just used as a negative DC offset as a reference and to energize the Op amps and Logic Gates, Etc.?

Since The Positive Voltage Regulator has to be 1 amp current output it's sinking and sourcing more for all the inputs and outputs of the Logic chips, the Pull up resistors or voltage dividers branches?

Also They put a .01uf and a 1K resistor in parallel with the ground to EARTH, this is a Noise/common mode rejection filter which takes out the Noise on the ground rail.

My Manager said that when you have difference IC chips analog op amps , Digital IC chips going to ground they have different potential differences on the ground and there is noise on the ground rail

Why would there be different potential difference on the ground from using different IC chips? ground is zero volts , so if you ground the IC chip to zero volts , how can there be a potential difference between the IC chips? and why is there noise on the ground rail?

 

[crutschow]

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Why would there be different potential difference on the ground from using different IC chips? ground is zero volts , so if you ground the IC chip to zero volts , how can there be a potential difference between the IC chips? and why is there noise on the ground rail?

Any ground voltage difference or noise is due to the fact that any practical ground point has greater than zero impedance, thus any ground current will cause a small voltage drop on it's way back to the supply. Ground inductance, in particular, will cause transient ground voltage spikes (ground bounce) due to the high frequency current spikes from switching digital logic. For this reason most boards with high frequency logic and/or analog circuits typically use a solid copper layer ground plane to minimize ground resistance and inductance.