difference between OTA and Opamp

what is the difference between an ota and opamp

Can any explain in details what is the difference between OTA and Opamp.

difference between ota and op amp

Basically the output resistance, OpAmp has low output resistance, OTA has high...
(Basically OpAmp: voltage controlled voltage source, OTA: voltage controlled current source)
If you have capacitive load, OTA fits better.

difference op amp

can u please give a more detailed answer without mentioning this votlage controlled currrent source and voltatge source.

difference between ota and gm stage

OP-AMP: one of the characterstics of ideal opa-mp is low output impedance ( it is used as voltage buffer). Therefore the output stage of op-amp has to be low impedance.
But if the output of the amplifier is seeing capcitive load, we don't add the low output impedance stage. (OTA)
If the output load is resistive in nature, the output stage has to be low impedance stage. (OP-AMP)
reason is left for you

output stage voltage limit ota

I like to repeat some former answers and, more than that, give some helpful additional information:

1.) OPAMP: Differential high impedance input and very low impedance output (voltage source) and a very high gain.

2.) OTA: Differential high impedance input and rather high impedance output (current source).
Thus, the relation between output and input is current/voltage=transconductance gm which has a final value. As an important feature the value of gm in commercial OTAs can be varied by a current into a separate pin.

Application:

3.) Opamps always are used with external feedback in order to create amplifier, filter, adding circuits, integrators,...... (Of course, they can drive also capacitive loads up to a certain limit)

4.) OTAs are used normally without external feedback (although it is possible and allowed). They have better high frequnecy capability than opamps. The output voltage is simply output current times load impedance. Since gm can be varied the gain can be controlled by an external control voltage.

To understand the OTA function you can think of it as a more or less ideal transistor with finite transconductance.

difference op-amp ota

Hi LvW,

Can you put some more light on the 4th point u mentioned...

ota voltage to current

OK, look at the following example of an integrating circuit using an OTA:

1.) The OTA is loaded with a capacitor C
2.) Output current: Iout=gm*Vin (Vin=Voltage between plus and minus input terminal, but one can be grounded if desired)
3.) Output voltage: Vout=(1/C)∫Iout*dt=(gm/C)∫Vin*dt
4.) In the frequency domain: Vout=gm/sC
5.) The integrating time constant tau=C/gm can be changed by externally controlling gm.

Any specific question ?
A good tutorial is: Active filter design using operational transconductance amplifiers, R.L. Geiger and E.S. Sanchez-Sinenzio (download from Sanchez home page)

difference between o t a and op amp

THANKS!!

current differencing opamap

LvW said:

3.) Output voltage: Vout=(1/C)∫Iout*dt=(gm/C)∫Vin*dt
4.) In the frequency domain: Vout=gm/sC Vin

Click to expand...

I think this valid at high frequency , but for low frequency Vout = - gm ro /(1+ sC ro) Vin

ota opamp buffer

Yes, of course, the simplified formula neglects the internal output resistance of the OTA. However, in any case a voltage buffer is needed. In this context, let me point to a very attractive solution using an opamp as a current-to-voltage converter.
When the integrating cap is placed between the opamp output and its inverting terminal (which in turn is connected directly to the OTA output) the influence of the finite OTA output resistance disappears.