| ??? 12/01/06 23:58 Read: times |
#128856 - High impedance Responding to: ???'s previous message |
Dear Kai
Sorry for being late because I've been away from my office for a while. Thank you for your guidance, I think I see some light now. I've never worked with ultra low current before. The schem I proposed doesn't seem to work using Wheatstone bridge. I know this is very low current, thus I chose the INA116 because the input bias current is very low according to the datasheet is only 3fA. As you said 300 Ohm bridge seems too weak to detect drop current. Kai can I drop the bridge configuration and connect a 10Mohm resistor across inputs of the Instrumentation Aplifier with respect to ground, the diode (DUT) is in series with the resistor then connect to the V source (20V)? http://www.8052.com/users/my8052/Diode%20test.JPG (The schematic doesn't refect the real IC because I don't have the library of the actual chip.) As you suggest I would use the chopping schem where the 20V will be switching on and off. Once again thank you for interesting in my problem. Have a great weekend. Best regards, T.L |
| Topic | Author | Date |
| Instrumentation Amplifier and Wheatstone bridge | 01/01/70 00:00 | |
| You need something high impedant | 01/01/70 00:00 | |
| High impedance | 01/01/70 00:00 | |
| Exactly! | 01/01/70 00:00 | |
| High impedance | 01/01/70 00:00 | |
| It should work but... | 01/01/70 00:00 | |
| It should work but... | 01/01/70 00:00 | |
| Offset voltage too high | 01/01/70 00:00 | |
| Offset voltage too high | 01/01/70 00:00 | |
| sources | 01/01/70 00:00 | |
| Sources | 01/01/70 00:00 | |
| have you considered that???? | 01/01/70 00:00 | |
| Details | 01/01/70 00:00 | |
| Details | 01/01/70 00:00 | |
| Go / No Go - tester | 01/01/70 00:00 | |
| Thank you!!!!!!!! | 01/01/70 00:00 | |
| T_on has no effect, but... | 01/01/70 00:00 | |
| Got it ;D | 01/01/70 00:00 | |
| Please modify your account, so that... | 01/01/70 00:00 | |
Site setting has been changed | 01/01/70 00:00 |