tag:blogger.com,1999:blog-19092890.post7555176680616919213..comments2024-03-28T17:41:43.970+02:00Comments on Image Sensors World: Column Settling Speedup ProposalVladimir Koifmanhttp://www.blogger.com/profile/01800020176563544699noreply@blogger.comBlogger10125tag:blogger.com,1999:blog-19092890.post-9831151154740701632012-04-29T22:14:56.406+03:002012-04-29T22:14:56.406+03:00I do not agree. Basically, one can zero the buffer...I do not agree. Basically, one can zero the buffer offset when it's connected to a reference voltage, then it remains zero when connected to whatever other signal.Vladimir Koifmanhttps://www.blogger.com/profile/01800020176563544699noreply@blogger.comtag:blogger.com,1999:blog-19092890.post-52513099341856739662012-04-29T20:32:29.632+03:002012-04-29T20:32:29.632+03:00Vladimir, the offset cannot be remmoved by auto-ze...Vladimir, the offset cannot be remmoved by auto-zero. Because the auto-zero is not set at the input voltage, so the difference between the reset level and the signal level has to be corrected by the amplifier and this causes offset.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-19092890.post-37790446568668701272012-04-29T18:48:08.816+03:002012-04-29T18:48:08.816+03:00The amplifier offset should be cancelled by auto-z...The amplifier offset should be cancelled by auto-zero. Still, the big cap needs some time to settle on noise, you are right. As the last graph in the post shows, the gain might be between 1.5 to 2.5, depending on the settling accuracy.Vladimir Koifmanhttps://www.blogger.com/profile/01800020176563544699noreply@blogger.comtag:blogger.com,1999:blog-19092890.post-71279528459361088052012-04-29T15:07:50.864+03:002012-04-29T15:07:50.864+03:00I've made a SPICE simulation on this circuit. ...I've made a SPICE simulation on this circuit. There are 2 problems:<br />1. the amplifier introduces an offset voltage<br />2. it takes the same RC decay for the column driver to absorbe this offset on the big cap.<br /><br />So all in all, the utility of this circuit is limited to my opinion. Any comments please?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-19092890.post-805611450519919662012-04-29T13:06:36.491+03:002012-04-29T13:06:36.491+03:00By adding buffer 17 you increase the bandwidth of ...By adding buffer 17 you increase the bandwidth of the noise and also add extra noise. Probably noise is not crucial in the application where you use this structure but wouldn't it be easier to just lower the sampling capacitance c1i?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-19092890.post-50337085424184294872012-04-28T22:35:01.348+03:002012-04-28T22:35:01.348+03:00what is the main advantage here compared to use si...what is the main advantage here compared to use simply the amp as a follower?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-19092890.post-31016557331407786312012-04-28T22:31:43.280+03:002012-04-28T22:31:43.280+03:00very useful indeed!very useful indeed!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-19092890.post-31621973317887976922012-04-26T23:44:40.105+03:002012-04-26T23:44:40.105+03:00Here are some other patent application publication...Here are some other patent application publications directed to speeding up the settling time of a column or preventing eclipsing.<br /><br />US 20060256220<br />US 20060227226<br />US 20060044414<br />US 20110019053<br />US 20080284891<br />US 20060203123<br />US 20040079973<br />US 20060278809<br />US 20060238634<br />US 20100118174<br />US 20070091193Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-19092890.post-18829363415293305822012-04-25T13:03:40.306+03:002012-04-25T13:03:40.306+03:00You probably meant C2i, not C17, right?
The paten...You probably meant C2i, not C17, right?<br /><br />The patent application assumes that Cp1 < C2i < C1i, as stated in Claim #2 and in "Solution to Problem" section, paragraph 2. You are right, it might be less effective when Cp1 is a dominating cap.Vladimir Koifmanhttps://www.blogger.com/profile/01800020176563544699noreply@blogger.comtag:blogger.com,1999:blog-19092890.post-69905290021137360642012-04-25T12:41:31.156+03:002012-04-25T12:41:31.156+03:00Please correct me if I am wrong: you first need to...Please correct me if I am wrong: you first need to charge Cp1 and C17 with the source follower of the pixel. Cp1 is often larger than Cs especially in large arrays..Anonymousnoreply@blogger.com