Zhangkun, if you mismatch the driving impedance then you will see a corresponding shift in offset voltage due to the bias current of the Op-Amp. For CMOS inputs, the current is very low, and a difference of 45K may mean a lot less error than say contamination on the PCB. But, if you are using a bipolar device, 45K may translate to a number of mV offset. You just have to plug those numbers into your error budget and see where you end up. Regards, Steve. At 10:40 AM 10/8/2003 +0800, Zhangkun wrote: >Dear All: >We are doing some simulation about operational amplifiers. I have one >question about the input of operational amplifiers. If the input impedance >of inverting input and non-inverting input are not same, does the >operational amplifiers work normally? > >For example, the resistor between vin- and inverting input of operational >amplifiers is 5K ohm and the resistor between vin+ and non-inverting input >of operational amplifiers is 50K ohm. Will the operational amplifier work >normally? > >Best Regards > >Zhangkun >2003.10.08 > > >------------------------------------------------------------------ >To unsubscribe from si-list: >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > >or to administer your membership from a web page, go to: >//www.freelists.org/webpage/si-list > >For help: >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >List archives are viewable at: > //www.freelists.org/archives/si-list >or at our remote archives: > http://groups.yahoo.com/group/si-list/messages >Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu