Also, depending upon the input parasitics (e.g. capacitance), the = bandwidth of the amplifier and the circuit topology used, large value = resistor (like 50K) in the feedback can easily turn the amplifier into = an oscillator. Performing a stability analysis taking parasitics into = consideration should mitigate this behavior. =20 Juergen Flamm -----Original Message----- From: Bi Han [mailto:mike_bihan@xxxxxxxxxxxx]=20 Sent: Wednesday, October 08, 2003 9:14 PM To: List` Si Subject: [SI-LIST] Re: operational amplifiers also depends on that you have feedback in your op-amp or not. steve weir <weirsp@xxxxxxxxxx> wrote:Zhangkun, if you mismatch the = driving impedance then you will see a=20 corresponding shift in offset voltage due to the bias current of the=20 Op-Amp. For CMOS inputs, the current is very low, and a difference of = 45K=20 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=20 offset. You just have to plug those numbers into your error budget and = see=20 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=20 >question about the input of operational amplifiers. If the input = impedance=20 >of inverting input and non-inverting input are not same, does the=20 >operational amplifiers work normally? > >For example, the resistor between vin- and inverting input of = operational=20 >amplifiers is 5K ohm and the resistor between vin+ and non-inverting = input=20 >of operational amplifiers is 50K ohm. Will the operational amplifier = work=20 >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:=20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages=20 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu --------------------------------- Do You Yahoo!? =C6=F4=D3=C3=B5=E7=D3=CA=D5=CA=BA=C5=A3=AC=C1=EC=BB=E1=D1=C5=BB=A2=CD=A8[= =C9=ED=C1=D9=C6=E4=BE=B3=C1=C4=B5=E7=D3=B0]=B5=C4=B6=AF=B8=D0=F7=C8=C1=A6= =A3=AC=BB=B9=D3=D0=CD=F8=C2=E7=C9=E3=CF=F1=CD=B7+=D1=C5=BB=A2=CD=A8=CA=D5= =D2=F4=BB=FA=B5=C8=C4=E3=C0=B4=C4=C3 ------------------------------------------------------------------ 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: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages=20 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ 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