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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> High speed, high mirror ratio current mirror https://designers-guide.org/forum/YaBB.pl?num=1211923481 Message started by jiesteve on May 27th, 2008, 2:24pm |
Title: High speed, high mirror ratio current mirror Post by jiesteve on May 27th, 2008, 2:24pm I am trying to design a current mirror with a high mirroring ratio (1:12, input current=40uA, output=480uA). Do you think the topology attached could work? How should I size the source follower and current source? I need very fast settling time, ~10ns. |
Title: Re: High speed, high mirror ratio current mirror Post by weber8722 on Mar 17th, 2009, 7:27am Hi, for good settling you need a frequency compensation. Use a series RC from input to Vdd, like 500fF + 10k. Otherwise you get a large overshoot and big noise peaking too. Bye Stephan |
Title: Re: High speed, high mirror ratio current mirror Post by rf-design on Mar 24th, 2009, 10:39am Very fast depending on your tech, Vdsat and Length. A good guess is to have a sqrt(12) * input current on the mirror buffer. |
Title: Re: High speed, high mirror ratio current mirror Post by vivkr on Mar 25th, 2009, 12:04am AnalogDE wrote on May 27th, 2008, 2:24pm:
I would also try to see if a Wilson current mirror could be used (headroom permitting). This is generally quite fast for high mirror ratios. Regards, Vivek |
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