# Electric Circuit

#### shailausa

Joined Sep 12, 2005
1
Hi Guys,
I'm having some problem to start one of my project on electric circuit. if some one can help me with that. i'm giving the problem below

I.Design an inductance simulator using op. amps, resistors and a capacitor to realize an inductance of 10.0 mH. Make sure that the capacitance value doesnt exceed 1.0 nF.

II.Design an RC bandpass amplifier that has a maximum gain of -20 at a frequency of 100 Hz with a bandwidth of 20 Hz. Make sure that the capacitor values do not exceed 1.0 µF and the resistor values do not exceed 100 kΏ.

The op. amps have a open circuit voltage gain (AV) of 105, input resistance (RI) of 100 MEGΏ and an output resistance (RO) of 100 Ώ.
I have no idea how to deal with that some one can helo how to proceede plz..

#### Brandon

Joined Dec 14, 2004
306
Originally posted by shailausa@Sep 12 2005, 07:58 PM
Hi Guys,
I'm having some problem to start one of my project on electric circuit. if some one can help me with that. i'm giving the problem below
I.Design an inductance simulator using op. amps, resistors and a capacitor to realize an inductance of 10.0 mH. Make sure that the capacitance value doesnt exceed 1.0 nF.

II.Design an RC bandpass amplifier that has a maximum gain of -20 at a frequency of 100 Hz with a bandwidth of 20 Hz. Make sure that the capacitor values do not exceed 1.0 µF and the resistor values do not exceed 100 kΏ.

The op. amps have a open circuit voltage gain (AV) of 105, input resistance (RI) of 100 MEGΏ and an output resistance (RO) of 100 Ώ.
I have no idea how to deal with that some one can helo how to proceede plz..
[post=10296]Quoted post[/post]​

I Put "gyrator" into google or looking in index for it. Its an OpAmp circuit which simulates a small inductor. Its highly used when space is an issue since a core and wound wire can be heavy and bulk but a SMT quadpack opamp and some SMT resistors are tiny.

II You have a 20 Hz bandwidth. Center Freq is 100Hz. Therefore w1=90, w2=110. Same thing, look in your book for a bandpass opamp filter design or google it. Your 2 corner frequencies are 100-10=90hz and 100+10=110hz. Your center gain of -20db means you need to probably use an inverting amp arrangment to get the gain below 1 since non-inverting has a 1+rf/rs gain (never less than 1).

#### sanjeev203

Joined Sep 19, 2005
7
Originally posted by Brandon@Sep 13 2005, 08:21 AM
I Put "gyrator" into google or looking in index for it. Its an OpAmp circuit which simulates a small inductor. Its highly used when space is an issue since a core and wound wire can be heavy and bulk but a SMT quadpack opamp and some SMT resistors are tiny.

II You have a 20 Hz bandwidth. Center Freq is 100Hz. Therefore w1=90, w2=110. Same thing, look in your book for a bandpass opamp filter design or google it. Your 2 corner frequencies are 100-10=90hz and 100+10=110hz. Your center gain of -20db means you need to probably use an inverting amp arrangment to get the gain below 1 since non-inverting has a 1+rf/rs gain (never less than 1).
[post=10299]Quoted post[/post]​
You can refer Book by Serda and Smith on "Microelectronics" for gyrators adn RC filters.