Comments for Notes http://notes.brooks.nu Notes for sharing Tue, 07 Feb 2012 02:39:47 +0000 http://wordpress.org/?v=2.6 Comment on AC Transistor Noise Analysis in HSPICE by lane http://notes.brooks.nu/2009/02/ac-transistor-noise-analysis-in-hspice/#comment-334 lane Sun, 05 Feb 2012 15:18:08 +0000 http://notes.brooks.nu/?p=143#comment-334 David, Yes you would see 15mV of noise at the output. This size of this noise is equal to 8/3kTgm. So to reduce it you have to increase the gm. Fruthermore, this is the output referred noise. The AC sim is used with a DC voltage source to verify the hand calculations from the parameters extracted from the DC operating point analysis. A noise sim, however, is the basically the same as an AC sim with different sources. Good luck. David,

Yes you would see 15mV of noise at the output. This size of this noise is equal to 8/3kTgm. So to reduce it you have to increase the gm. Fruthermore, this is the output referred noise.

The AC sim is used with a DC voltage source to verify the hand calculations from the parameters extracted from the DC operating point analysis. A noise sim, however, is the basically the same as an AC sim with different sources.

Good luck.

]]> Comment on AC Transistor Noise Analysis in HSPICE by David Levy http://notes.brooks.nu/2009/02/ac-transistor-noise-analysis-in-hspice/#comment-333 David Levy Wed, 01 Feb 2012 16:38:49 +0000 http://notes.brooks.nu/?p=143#comment-333 Thank you for this information. It is helpful. If we had an actual circuit like this, with a real (high impedance current source), and looked at the drain of this transistor in the lab with a digital volt meter, would we see an rms noise on the drain on the order of 15 mV? In other words, if the dc output was 10V would we see 10V +/- 0.015V? 15 mV of total integrated rms noise seems like a surprisingly large number. I have to redesign a complex power amplifier for lower noise performance, and noise is one of the areas that I don't have a lot of experience in. It appears from my limited experience that one doesn't need an ac source to do noise analysis. Although it was useful for hand calculations to do an ac sim, could you run your noise analysis with a dc source biasing the gate of your nmos transistor? Thank you for this information. It is helpful.

If we had an actual circuit like this, with a real (high impedance current source), and looked at the drain of this transistor in the lab with a digital volt meter, would we see an rms noise on the drain on the order of 15 mV? In other words, if the dc output was 10V would we see 10V +/- 0.015V?

15 mV of total integrated rms noise seems like a surprisingly large number.

I have to redesign a complex power amplifier for lower noise performance, and noise is one of the areas that I don’t have a lot of experience in. It appears from my limited experience that one doesn’t need an ac source to do noise analysis. Although it was useful for hand calculations to do an ac sim, could you run your noise analysis with a dc source biasing the gate of your nmos transistor?

]]> Comment on Chronovu USB LA-8 Logic Analyzer by Cordova http://notes.brooks.nu/2010/08/chronovu-usb-logic-analyzer/#comment-332 Cordova Wed, 11 Jan 2012 20:00:49 +0000 http://notes.brooks.nu/?p=174#comment-332 I'd recommend using the Intronix LogicPort LA1034. No deep memory but you get excellent sample compression (transitional sampling) and superior 2-level triggering makes it easy to capture the logic state that you want to see. Install the mature and intuitive software in a virtual machine and run in demo mode to read the professionally written user manual. Click Help. To my knowledge there is no separate manual.pdf unfortunately. Good luck. I’d recommend using the Intronix LogicPort LA1034.
No deep memory but you get excellent sample compression (transitional sampling) and superior 2-level triggering makes it easy to capture the logic state that you want to see. Install the mature and intuitive software in a virtual machine and run in demo mode to read the professionally written user manual. Click Help. To my knowledge there is no separate manual.pdf unfortunately. Good luck.

]]> Comment on Gstreamer Video Crossfade Example by rossana http://notes.brooks.nu/2011/01/gstreamer-video-crossfade-example/#comment-320 rossana Tue, 11 Oct 2011 00:19:34 +0000 http://notes.brooks.nu/?p=261#comment-320 I translate this code to C, it works, but without sound. Any sugestion to a needed modification to this pipeline?. Thanks and best regards rossana I translate this code to C, it works, but without sound. Any sugestion to a needed modification to this pipeline?.
Thanks and best regards

rossana

]]> Comment on exim rewrite subject based on spam by scottInNH http://notes.brooks.nu/2008/03/exim-rewrite-subject-based-on-spam/#comment-310 scottInNH Mon, 12 Sep 2011 14:15:47 +0000 http://www.ubixum.com/wordpress/archives/21#comment-310 Beware, this method of subject rewrite will break UTF-8 encoded subject lines. This method works fine for plain-English (which are typically unencoded) subjects. Beware, this method of subject rewrite will break UTF-8 encoded subject lines. This method works fine for plain-English (which are typically unencoded) subjects.

]]> Comment on Python gstreamer controller by rossana http://notes.brooks.nu/2011/01/python-gstreamer-controller/#comment-309 rossana Thu, 08 Sep 2011 23:12:12 +0000 http://notes.brooks.nu/?p=235#comment-309 First, thanks for your response. Second, sorry for too many posts. I didn't see the previous one when I check your blog, I thought they got lost. I wasn't clear enough. actually I know what the alpha channel is. I don't know how to ensamble these channel with the video streamer, there's no connection between the video sources and the operation bin which has the alpha channels. I assume alpha1 'runs' first, since alpha2 has a start time. My question it's more focused on how GStreamer elements work in this example. Thanks a lot, best regards. Rossana First, thanks for your response. Second, sorry for too many posts. I didn’t see the previous one when I check your blog, I thought they got lost.

I wasn’t clear enough. actually I know what the alpha channel is. I don’t know how to ensamble these channel with the video streamer, there’s no connection between the video sources and the operation bin which has the alpha channels. I assume alpha1 ‘runs’ first, since alpha2 has a start time.

My question it’s more focused on how GStreamer elements work in this example. Thanks a lot, best regards.
Rossana

]]> Comment on Python gstreamer controller by lane http://notes.brooks.nu/2011/01/python-gstreamer-controller/#comment-308 lane Thu, 08 Sep 2011 18:47:54 +0000 http://notes.brooks.nu/?p=235#comment-308 Rossanna, See http://en.wikipedia.org/wiki/Alpha_compositing I do not use a decodebin2 in the crossfade example because I use generated video streams. Rossanna,

See http://en.wikipedia.org/wiki/Alpha_compositing

I do not use a decodebin2 in the crossfade example because I use generated video streams.

]]> Comment on Python gstreamer controller by rossana http://notes.brooks.nu/2011/01/python-gstreamer-controller/#comment-307 rossana Thu, 08 Sep 2011 18:34:13 +0000 http://notes.brooks.nu/?p=235#comment-307 Hello, actually I saw your crossfade example, I am new programming with GStreamer and with audio/video issues. I don't get why you don't use a decodebin2 or player in that example as you use in this one. Second, could you please explain me which rol and the strategy the alpha channel take?. Thanks a lot in advance. Rossana Hello, actually I saw your crossfade example, I am new programming with GStreamer and with audio/video issues. I don’t get why you don’t use a decodebin2 or player in that example as you use in this one.
Second, could you please explain me which rol and the strategy the alpha channel take?.
Thanks a lot in advance.

Rossana

]]> Comment on Python gstreamer controller by rossana http://notes.brooks.nu/2011/01/python-gstreamer-controller/#comment-306 rossana Thu, 08 Sep 2011 05:00:34 +0000 http://notes.brooks.nu/?p=235#comment-306 Sorry I refer to crossfade example, but I couldn't post a comment. Regards Sorry I refer to crossfade example, but I couldn’t post a comment.
Regards

]]> Comment on Python gstreamer controller by rossana http://notes.brooks.nu/2011/01/python-gstreamer-controller/#comment-305 rossana Thu, 08 Sep 2011 04:42:55 +0000 http://notes.brooks.nu/?p=235#comment-305 Hi, I am totaly new programming with GStreamer and with audiovisual issues as well. I don't get the alpha channels strategy. How is the behavior of these channels with the video. I understand de alpha2 get into scene at a certain time to help the crossfade phase. I appreciate your response, thanks. Hi, I am totaly new programming with GStreamer and with audiovisual issues as well. I don’t get the alpha channels strategy. How is the behavior of these channels with the video. I understand de alpha2 get into scene at a certain time to help the crossfade phase. I appreciate your response, thanks.

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