Powering a circuit with a rectifier

Two ways of dealing with this:

1. Ensure that you have the tran analysis before the sp analysis in ADE (you can drag and drop them into the right order) and then ensure that the sp analysis has the option prevoppoint=yes set on the sp options form. 
2. On the tran analysis options look for the actimes/acnames fields and enter a time near the end of the transient for the actives and "sp" for the acnames.

The first will just ensure that that it runs the sp analysis under the operating point at the end of the preceding transient. The second will run the sp analysis during the tran analysis at the specified time, using the operating point at that time (you can run at multiple times this way).

Hope that helps,

Andrew.

Thank you so much!! it works.

But, is there a way to get the Noise figure of the LNA and rectifier in sp analysis? currently my noise figure is the same with a rectifier  or with a Vdd.

I want the total noise at the output including the rectifier. since the rectifier just replaces the Vdd, I want the systems noise with the noise added by the rectifier.

do I have to run a specific simulation for that?

I hope you understand my question

Regards,

Thank you so much!! it works.

But, is there a way to get the Noise figure of the LNA and rectifier in sp analysis? currently my noise figure is the same with a rectifier  or with a Vdd.

I want the total noise at the output including the rectifier. since the rectifier just replaces the Vdd, I want the systems noise with the noise added by the rectifier.

do I have to run a specific simulation for that?

I hope you understand my question

Regards,

It would probably be useful to understand what the rectifier looks like? My guess is that it can't be treated as linear time-invariant, and so you might need to do a PSS analysis over the period of the AC signal driving the rectifier, and then do a pnoise or psp analysis to measure the noise figure. However, that's a guess since I really don't know how your circuit actually works ("rectifier" covers a lot of possibilities).

Andrew.

the rectifier is a 3 stage  MOSFET (instead of diodes) Dickson charge pump. its working fine and charging, its powering the LNA but the noise it produces is not calculated for some reason. In sp, "do noise" you can only add the input and output port which are reserved for the LNA. is there a way to make it take the 3rd port (the one sending power to the rectifier) to the sp analysis? or the only way is to use PSS or PSP?

Do I have to configure the pss the same way as something similar to "prevoppoint" for the sp?

Regards,

A Dickson charge pump is a periodic circuit (you have a clock) - you cannot just use a linear analysis such as "sp" on it because it doesn't have a single fixed operating point - instead it has a periodic operating point.

So, rather than running DC analysis or transient to reach a static operating point you need to capture a period of operation at the final settled steady state (PSS can do this; PSS inherently finds the settled steady state, but if the start behaviour is fairly nonlinear you might have to specify a long enough tstab to get it closer to being settled - you typically don't have to give the tstab as the final settled time though). Then you run PSP or PNOISE - this will automatically run after the PSS and will compute the s-parameters or noise figure around a time-varying operating point. Essentially you're then computing the time-averaged response over your clock frequency and the "small-signal" analysis such as PSP/PNOISE is using a time-varying linearisation of the circuit to compute the noise and transfer functions. No need to use prevoppoint - the PSS captures the settled periodic operating point, and the PSP or PNOISE computes the small-signal behaviour around that time-varying operating point.

It might be useful to read something like this useful document on use of PSS for switch-capacitor circuits.

Regards,

Andrew.

Thank you Mr. Andrew,

But still the noise of the rectifier is not being considered at the output of the LNA. The noise with the rectifer is the same as with Vdd. tried Pnoise and PSS. I will keep trying looking into it

Regards and Thank you so much,

There's probably not much more that I can suggest without seeing the setup and circuit - for that it would be best to contact customer support.

Regards,

Andrew.