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Design >> RF Design >> Noise in Power supply
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Message started by Mahbub Reja on Oct 26^th, 2005, 4:05pm

Title: Noise in Power supply
Post by Mahbub Reja on Oct 26^th, 2005, 4:05pm

Oct 26, 2005

Hi,
Any one can please tell me what kind of power supply should I use for simulating high frequency RF ircuits (LNAs mixers, VCOs, amplifiers). If I use noisy power supply (amplitude of noise 50mv-200mv pp), I see my circuit does not work because RF input signals to LNAs and mixers very low. Should I use very clean power supply. In real case VDD and VSS PADS are connected through bond-wires. if I run simulation adding these bond wires inductors (2nH -4nH) from VDD to the power rail of the circuit and VSS to the ground-rail of the circuit, it adds excessive noise in supply and instead of signal, noise is amplified.
I am not sure, what is the practice of RF design, I should use clean power supply or use de-coupling capacitance between VDD and VSS for noisy power supply.

Thanks

Mahbub Reja

Title: Re: Noise in Power supply
Post by neoflash on Nov 6^th, 2005, 3:27am

Use real circuit to mimic your noise source.

RF circuit is different from mixed-signal design. Much noise is correlated with signal, so adding sin wave in power supply can not depict the real condition.

You need to estimate your real case bonding wire inductance, thus you decide how much decoupling you need.