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https://designers-guide.org/forum/YaBB.pl Design >> RF Design >> a question about linear pa. https://designers-guide.org/forum/YaBB.pl?num=1242982455 Message started by liuqing2050 on May 22nd, 2009, 1:54am |
Title: a question about linear pa. Post by liuqing2050 on May 22nd, 2009, 1:54am i am a new designner of linear pa. now, i have some problems in how to simulation the linearity of pa. evm depicts the in-band distortion and acpr depicts the out-band distordion, what abot the am-am am-pm means? for in-band or out-band? i find a strange problem, i design two pa. the simulation am-am and am-pm of the two pa are nearly similar. but the simulaton im3 has 10 dbc difference. why the im3 has so lage difference? |
Title: Re: a question about linear pa. Post by liuqing2050 on May 22nd, 2009, 1:55am thank you for your answers! |
Title: Re: a question about linear pa. Post by pancho_hideboo on May 22nd, 2009, 5:35am waseda-rfic wrote on May 22nd, 2009, 1:54am:
waseda-rfic wrote on May 22nd, 2009, 1:54am:
The following is one possiblity for your case. Maybe AM/AM characteristics of one PA is dominated by output nonlinearity rather than input nonlinearity. On the other hand, AM/AM characteristics of the other PA is dominated by input nonlinearity. |
Title: Re: a question about linear pa. Post by liuqing2050 on May 22nd, 2009, 7:44pm thank you very much for your advise. In my simulation, the AM-PM distortion is 4 degree at 16 dbm input (one stage pa) and IM3 is -10 DBc, in another PA (one stage pa) the AM-PM distortion is 4 degree at 12dbm input and IM3 below -20 DBc. the two PA output p1dbs are nearly the same. so what causes this difference? if as you says,Maybe AM/AM characteristics of one PA is dominated by output nonlinearity rather than input nonlinearity.On the other hand, AM/AM characteristics of the other PA is dominated by input nonlinearity. i want to ask a question. in a cmos pa, whether the nonlinearity of Cgs dominats the input nonlinearity and the nonlinearity of Rds dominats the output nonlinearity and which is more important? |
Title: Re: a question about linear pa. Post by liuqing2050 on May 23rd, 2009, 7:40am pancho_hideboo wrote on May 22nd, 2009, 5:35am:
you mean input nonlinearity is the nonlinearity of pa? |
Title: Re: a question about linear pa. Post by liuqing2050 on May 23rd, 2009, 6:54pm hi pancho_hideboo thank s for your help! |
Title: Re: a question about linear pa. Post by liuqing2050 on May 23rd, 2009, 7:33pm hi pancho_hideboo thanks for your help! by the way, do you know transforme based power combining? my simulation IM3 is asymmetry. may be some problems in my transforme? |
Title: Re: a question about linear pa. Post by pancho_hideboo on May 23rd, 2009, 9:30pm waseda-rfic wrote on May 23rd, 2009, 7:33pm:
http://www.designers-guide.org/Forum/YaBB.pl?num=1243131271 So a frequency characteristics exists in your PA. Asymmetrical IM3 is quite natural result when there is a frequency characteristics. http://cp.literature.agilent.com/litweb/pdf/5989-8889EN.pdf |
Title: Re: a question about linear pa. Post by liuqing2050 on May 25th, 2009, 1:44am Hi pancho_hideboo thanks! |
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