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ic_engr Senior Member Offline Posts: 135	AM modulation Feb 18^th, 2010, 5:23am Hello Folks, I would like to set-up 80% 1kHz AM modulation on a 900MHz RF signal. In Cadence what will be the easiest way to perform this set-up ?. I was thinking of two voltage sources (vsin) in series, a 1kHz sinewave and another 900MHz sinewave in series. I am not sure how I will have the 80% modulation specified ?. Any suggestions. ic_engr
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pancho_hideboo

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Re: AM modulation
Reply #1 - Feb 18^th, 2010, 5:33am

I can't find out any design issue in your post.
Your question is no more than easy usage of simulator.
Please post to Simulator's board or read documents of your simulator.

ic_engr wrote on Feb 18^th, 2010, 5:23am:

I would like to set-up 80% 1kHz AM modulation on a 900MHz RF signal.
In Cadence what will be the easiest way to perform this set-up ?

If you mean Cadence Spectre, simply use "analogLib/vsin" or "analogLib/vsource".
Here "ammodindex ; AM modulation index" and �"ammodfreq ; AM modulation freq" are available.
See parameters of the followings.
http://edocs.soco.agilent.com/display/ads2009/vsin
http://edocs.soco.agilent.com/display/ads2009/vsource

Again see http://www.designers-guide.org/Forum/YaBB.pl?num=1233850018

If you use Golden Standard simulator HSPICE, use "analogLib/vsin" not "analogLib/vsource".

ic_engr wrote on Feb 18^th, 2010, 5:23am:

I was thinking of two voltage sources (vsin) in series,
a 1kHz sinewave and another 900MHz sinewave in series.

It seems you can't understand frequency spectrum of AM signal at all.
If you would like to generate AM signal by synthesization of spectrum, connect three "vsin" in series.
Here their frequencies are 900MHz, 900MHz-1kHz and 900MHz+1kHz.
I assume amplitude of 900MHz component is "A". Amplitudes of both 900MHz-1kHz and 900MHz+1kHz have to be "0.8*A/2".

BTW, have you been able to understand basic modulation including GMSK ?
http://www.designers-guide.org/Forum/YaBB.pl?num=1263572424

The followings are general notes for you.

- Always describe vendor's name which you use as tool or simulator.
- Don't do multiple posts which are same content.
- Don't request source code or behavioral model without any efforts.
- There are many simulators which have analyses called as PSS, PAC and Pnoise.
- Describe in detail with using correct terminologies.
- Warnigns are different from Errors.
- ADS is not name of simulator.
- There is no tool which name is Cadence.
- Don't use Direct Plot of Cadence ADE blindly without knowing definition.
- All gains in Direct Plot of Cadence ADE are "right", "true" and "practical" voltage gain.
- Don't mix up Simulation with Post Processing. They are completely different phase.
- MATLAB are different from Simulink.
- Learn measurements using actual instruments. Not "EDA Tool Play

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« Last Edit: Feb 18^th, 2010, 11:31am by pancho_hideboo »

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http://www7.plala.or.jp/ungeromeppa/flash/kita.html
http://www.youtube.com/watch?v=mjIxGh55bMM&feature=related

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RFICDUDE

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Re: AM modulation
Reply #2 - Feb 27^th, 2010, 4:24am

If you are trying to create AM double sideband then you will need three sinusoidal sources: one for each sideband and also the carrier.

100% modulation accurs when the amplitude of each sideband is 50% of the carrier amplitude.
Ac=2*Asb

x(t)=Ac*cos(wc*t)+Asb*cos[(wc-wsb)*t]+Asb*cos[(wc+wsb)*t]

You can scale the sideband amplitude down reduce the % modulation.

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pancho_hideboo

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Re: AM modulation
Reply #3 - Feb 27^th, 2010, 4:32am

RFICDUDE wrote on Feb 27^th, 2010, 4:24am:

If you are trying to create AM double sideband then you will need three sinusoidal sources: one for each sideband and also the carrier.

100% modulation accurs when the amplitude of each sideband is 50% of the carrier amplitude.
Ac=2*Asb

x(t)=Ac*cos(wc*t)+Asb*cos[(wc-wsb)*t]+Asb*cos[(wc+wsb)*t]

You can scale the sideband amplitude down reduce the % modulation.

I've already described like following.
pancho_hideboo wrote on Feb 18^th, 2010, 5:33am:

ic_engr wrote on Feb 18^th, 2010, 5:23am:

I was thinking of two voltage sources (vsin) in series,
a 1kHz sinewave and another 900MHz sinewave in series.

It seems you can't understand frequency spectrum of AM signal at all.
If you would like to generate AM signal by synthesization of spectrum, connect three "vsin" in series.
Here their frequencies are 900MHz, 900MHz-1kHz and 900MHz+1kHz.
I assume amplitude of 900MHz component is "A". Amplitudes of both 900MHz-1kHz and 900MHz+1kHz have to be "0.8*A/2".

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Kita━━━━━━(ﾟ∀ﾟ)━━━━━━ !!!!!
http://www7.plala.or.jp/ungeromeppa/flash/kita.html
http://www.youtube.com/watch?v=mjIxGh55bMM&feature=related

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RFICDUDE Community Fellow Offline Posts: 323	Re: AM modulation Reply #4 - Mar 1^st, 2010, 4:41pm Ah, yes you did. I simply did not read your entire response. I apologize for the redundant response. RFICDUDE
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