Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

PLEASE HELP !!! :One LDO supplying voltage for two circuits

Status
Not open for further replies.

ericz

Junior Member level 3
Junior Member level 3
Joined
Jul 2, 2005
Messages
27
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,579
Hi all,

Can I use only one LDO that supplies current for two circuits (for example, the LDO will maintain the voltage for Amplifier and for PLL and VCO all together).

Is this concept is common or this is bad idea?

can anyone give me some links for such examples which are bad or good?

Thanks,
 

Re: PLEASE HELP !!! :One LDO supplying voltage for two circu

LDO is to prevent noise from vco or pll going into power. If amp and vco share a LDO, noise from vco will greatly destroy amp.
In general, one ldo for vco, one ldo for otther parts of PLL(pfd, devider), another for amp.
 

    ericz

    Points: 2
    Helpful Answer Positive Rating
Re: PLEASE HELP !!! :One LDO supplying voltage for two circu

It is possible to share the same LDO for the circuit but as mentioned by Flushrat, if the PLL and VCO contriute some of amount of noise which will affect other block of amplifers due to coupling, then it is advisable to have different LDO shared. Normally those blocks/amplifiers which operated in higher signal switching then they will have different LDO.
 

Re: PLEASE HELP !!! :One LDO supplying voltage for two circu

Decoupling
There are instances where the power distribution between stages cannot be sufficiency bypassed. In this case, the designer might be tempted to use several different power supplies. However, by supplying the DC power to each stage through a separate inductor or "choke," while also bypassing to ground that stage, the effect is the same. That is to say, the choke offers a high impedance path to any errant signals or noise between stages, while offering a very low resistance path to the DC power: this is known as decoupling. Active devices such as voltage regulators can also be used for decoupling stages.

In the rest of this section (DECOUPLING) you will find pros and cons on using active separation with voltage regulators or passive with LC ..

http://www.williamson-labs.com/480_byp.htm

Regards,
IanP
 

    ericz

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top