GSM PA supporting big capacitor seletion

Hi,

Would you select 22uF / 6.3V or 10uF / 10V for supporting
PA current poul ? I have only limited size on 0805.
I use Skyworks PA.

Thanks

The more capacitance is better but you have to answer the questions:

What is the supply voltage of the PA compared to the WVDC of the capacitor? Rule of thumb is WVDC must be 50% higher.

How does the capacitance change over temperature?

Is the WVDC steady over temperature?

What is the ESR and does it hold over temperature?

Depends on current of consumption...
And also, connect some additional tanatalum, ceramic ( mica better ) capacitors at different harmonic frequencies,spurs...

Putting just a electrolyitic capacitor is not a good solution..
Consider the others..

Hi Guy,

Thanks for the comment.
Can I know what's the WVDC ? Is that related to voltage rating of the
capacitor ? If so, how comes 50% larger only ....

Regards,
wilson

WVDC is Working Voltage Direct Current. Yes, its the voltage rating of the capacitor. You need some headroom to account for ripple, transients, and temperature changes. 50% headroom is a rule of thumb for good design practice. If you have a 3.3 VDC supply you would use a capacitor with 5 WVDC rating. You could use a 3.3 WVDC but you had better carefully study your circuit and the capacitor or else risk a fire.