Analog Power Supply Noise Requirements

[ballimo]

Hello Designers,

I 'am designing the power supply for a optical module, in the datasheet they specify the Analog supply noise as 25 nV/root-Hz @ F= 300 MHz!? did any one have any idea how can I achieve this Noise floor specification? the analog supply is 1 V and the output current is 3 A.

I was thinking to use a LDO, but I did not find any one with 1V output. does any one have a suggestion any document ....

Many thanks,

Ballimo

 

[itaig]

Hi there,

try a LP38501 or LP38503 made by National Semiconductor. These are low noise adjustable 3.0A LDO regulators that can go down to 650mV. The data sheet only specifies noise levels upto 100kHz. Make sure you use decent decoupling. Use high grade ceramics especially near the load.

**broken link removed**

 

[pauloynski]

Use a buck converter like TPS54373. To achieve a low noise floor at high frequencies you´ll need to carefully filter the output using a LC circuit.