op-amp design problem

[terry_kchai]

2 stage op-amp

How to design an op-amp with unity-gain bandwidth of 5MHz and maintain 50-60dB voltage gain? who could tell me which topology suitable for this?
Thanks

 

[amitjagtap]

current mirror op amp design

for the mentioned specs even conventional two stage opamp is suitable.
Which technology u r using?.
Well the design procedure is not fixed is changes according to what u want.

 

[terry_kchai]

how to design op amp

This is based on 0.35um 5V CMOS process.
I want output res to be low so using a series-shunt feedback.
Maybe enlarging my bandwidth-product can be a way, but how to do that?
First of all, I need to choose a appropriate structure.
Can you help me?

 

[freescale_bharat]

You go ahead with 2 stage op-amp. With 0.35u technology you can easily get gain of around 60dB. Avoid using the large diff pair as larger W may prove as diminishing return due to parasitic cap.

 

[supreet_95]

You can use nmos differential input pair with 2nd stage being inverter with active load. Increase the current of first stage to increase ur bandwidth. U can use differential pmos and nmos cascode structures to increase the resistance of first stage and hence gain. U can get a worst case gain of 80dB easily with this for power supply of 3.3V or above. Hope the input is not rail to rail.

 

[terry_kchai]

Please take a look at this pic.
Actually, my input ranges from 80mV to 1.2V, and need output pass PMOS(MP8) could source 50mA current to drive a transformer. Power supply is 5V. Output swing should be 300mV to 4V
As simulation showed, the BW is very small, -3dB freq is around 1Hz.How to improve this?
Can you help ?
Thanks

 

[supreet_95]

Please cross check the polarity connection for negative feedback.

 

[terry_kchai]

Yes, it is a negative FB. Anything wrong with this schematic?

 

[foenixin]

yah, it is right, 2-stage opa.

 

[northeast1]

How to design an op-amp with unity-gain bandwidth of 5MHz and maintain 50-60dB voltage gain? who could tell me which topology suitable for this?
Thanks

this is a easy problem, all tow stage op can easy get this target.

 

[jeffsky520]

yah, it is right, 2-stage opa.

polarity connection is right? confused. Could you please explain it clearly ? Thanks.

 

[chibijia]

i want to op works on subthreshold region ,how to design it.

 

[tia_design]

the most convential two stage op amp can do, first stage is with current mirror, and the second stage is common source with current mirror load.

 

[northeast1]

How to design an op-amp with unity-gain bandwidth of 5MHz and maintain 50-60dB voltage gain? who could tell me which topology suitable for this?
Thanks

It is sample, normal two stage class a op is suitable.