An interesting LT app note on low noise measurement

[NickKUK]

https://www.analog.com/en/app-notes/an-159.html

This seemed interesting.. includes using THAT bjts.

 

[oliverwon90]

Poor rejection from a linear regulator will bring switching regulator residue or other unwanted signals through, corrupting the hard work done to ensure a clean supply

 

[NickKUK]

Poor rejection from a linear regulator will bring switching regulator residue or other unwanted signals through, corrupting the hard work done to ensure a clean supply

Possibly why the cookie tin/copper/mu metal shielded device used batteries.

 

[bohrok2610]

When LT3042/45/94 are used as post-regulators after switching regulator the input capacitor should often be left out. With TPS7A47/33 in same function the input capacitor is needed.

 

[gpapag]

The take away from the AN is that if an external capacitor is to be placed across the output of the switching regulator, it should be placed physically closest to the switcher board and not at the post regulator board input for magnetic loop minimization (fig. 19 to 21 and associated text)
George

 

[bohrok2610]

Most switching regulators need to have an output capacitor or otherwise they will oscillate to death. Input capacitor of post-regulator is another thing.

 

[NickKUK]

I quite liked the amp as a scope amp.

 

[HalFoster]

The take away from the AN is that if an external capacitor is to be placed across the output of the switching regulator, it should be placed physically closest to the switcher board and not at the post regulator board input for magnetic loop minimization (fig. 19 to 21 and associated text)
George

Seriously? That is your takeaway from the whole app note?