How do you get this waveform?

[JiL0]

calculator harmonicfreq cadence

Does anyone knows how to simulate a circuit to determine the harmonics of the circuit? What simulation should i conduct ( AC, DC, PSS...etc ) in order to obtain a waveform as shown in the picture?

I'm using cadence and i'm trying to simulate the harmonics of a filter, ADC and opamp. Really hope someone can help.

 

[nkchenliy]

cadence harmonicfreq

If you simulate ADC, you will input sin or two-tone sin signal. Then, you will FFT the simulation result. OK, you will use matlab to obtain the waveform.

 

[santhoshv78]

cadence harmonicfreq function

In cadence wave form viewer also u can get this waveform by plotting the FFT or DFT for a perticular number of cycles and record points for the sinewave input.

 

[xusoso]

you can get the matlab toolbox on this web site **broken link removed**

 

[JiL0]

What i did was, i perform a transient analysis with an input signal of 10kHz. Then i plot of the output on the waveform window. Then i chose calculator. I selected the output wave into the calculator's buffer. Then i choose DFT under the special function. In the DFT option form, i key in from 10k to 1M , number of sample 64, window type rectangular, coherant gain= none. Then i click plot.

What i get is a graph with a vertical line at 0 and zero elsewhere.

 

[micel99]

You can use FFT function in calculator or maybe harmonicfreq.

 

[nkchenliy]

You can obtain the matlab program from http://www.mit.bme.hu/projects/adctest.

 

[JiL0]

I tried using harmonicfreq and also harmonic. Wat i did was i did a transient analysis. The i add the output wavefrom into the calculator buffer. Then i chose special function harmonicfreq/harmonic. Under harmonic number, I chose any number (1-10) and i click plot. But the CIW says the wave is not a waveform object that can be displayed and will be turned OFF automatically.

 

[JiL0]

Sorry, i dont have a matlab programme. Is it possible to do it on cadence?

 

[JiL0]

Thanks everyone. I think i got it. Must change the yaxis to log scale.

Thanks for all your tips.


Update: But it is only for DFT. Still cant get the continuous harmonics waveform

 

[dwang_w]

the running time and frequency of sin is strict needde, u can refer to some paper about the FFT analysis

 

[JiL0]

Sorry, dont really get wat you mean. Can give a simple example?

 

[dwang_w]

hi