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Measurements >> Phase Noise and Jitter Measurements >> SSB/DSB, it is a problem
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Message started by neoflash on Jan 25^th, 2007, 7:35am

Title: SSB/DSB, it is a problem
Post by neoflash on Jan 25^th, 2007, 7:35am

I'm a little get confused by definition of SSB phase noise and DSB phase noise.

In ELDO definition, SSB is 3dB lower than DSB phase noise. It means SSB only contains one-sided power.

In Ken's paper on oscillator, SSB is 3dB higher. It means SSB contains both sides of power.

Which one is right?

What is obtained from Agilent E5052A? Is it SSB or DSB? Its total power need integration from -oo ~ + oo, or it only requires integral from 0~+oo?

Also, what is the SSB noise obtained from spectraRF? Is it the same as Ken's definition or agree with ELdos?

Thanks,
Neoflash

Title: Re: SSB/DSB, it is a problem
Post by ACWWong on Jan 28^th, 2007, 5:18am

I'm not sure how relevant this is, but in the context of noise figures for receivers, I have noticed in the past that Agilent (in measurement application notes) that SSB NF is 3dB lower than DSB NF, with the my interpretation as if one only includes SSB NOISE, then take DSB NOISE, then the DSB noise will be 3 dB higher (if symetrical).

In Cadence tools like spectreRF (and Razavi's "RF microelectronics"), they describe from the point of viewpoint of a signal. If a signal exists in both sidebands of an oscillator used in RF downconversion (e.g. ZIF), then this is considered DSB as the signal exists on both sidebands... so the resultant noise figure is 3 dB lower than the SSB signal case. In the SSB signal case, there is no signal at the image, but the noise does exist, so when down converted it ends up increasing the receiver NF by 3dB.

So there seemed to be a different definition for SSB and DSB NF between Agilent and Cadence tools... so probably best thing to do is find out what ELDO is doing and read you aglient apps notes, and be clear to yourself what each tool is doing and what figure of merit is relevant to you...