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Design >> Mixed-Signal Design >> question about switches
https://designers-guide.org/forum/YaBB.pl?num=1199615213

Message started by James Bond on Jan 6^th, 2008, 2:26am

Title: question about switches
Post by James Bond on Jan 6^th, 2008, 2:26am

Hi, all,

I designed a switch to switch off the capacitor, during the simulation when switch is off, I found that the AC signal is almost blocked, with 0.9Vpp input to the switch, only 0.5mVpp passed, but the input signal has a dc level about 0.9V, and after the switch, it has a dc level about 0.4V, Can I consider the switch is off ? Since after swith is the capacitor, so I think the dc will not affect my ac operation , right ? Please give me some suggestions.Thank you very much.

james

Title: Re: question about switches
Post by ywguo on Jan 6^th, 2008, 9:57pm

Hi James,

Would you please post the schematic and the waveform? I think that the switch is switched off.

Yawei

Title: Re: question about switches
Post by Berti on Jan 6^th, 2008, 10:13pm

Hi,

Since the switch is off, you basically have a capacitive voltage divider. Therefore you can easily calculate whether the 0.4V is reasonable or not.

Regards