amplifier design - Av=10000, swing=1.8v, Vdd=1.8

[keith1200rs]

Re: design amplifier

In this paper all condition for Vsup>2.5
In my project Vdd=1.8
Is Vsup equal with Vdd?

The paper is an example of an amplifier which can work at low voltages. You need to do your own design but there is no reason why the circuit couldn't be made to work at 1.8V.

Keith

Added after 2 minutes:

tnx john
the problem of cascode is swing. swing=Vdd-4Vod

That's why you need to be looking at FOLDED cascode.

Keith

 

[jgk2004]

design amplifier

Keith is correct you definitely need a folded cascode. The JSSC paper is an improvement on a folded cascode with battery class AB output. You still need to boost the cascode to meet your 80dB gain needed if you build a 2 stage design. Are you designing for high gain low GBW? or both high. If so a three stage design will be more power efficient...

 

[laperla]

Re: design amplifier

The paper is an example of an amplifier which can work at low voltages. You need to do your own design but there is no reason why the circuit couldn't be made to work at 1.8V.


It's tru but dosen't obvious give me this result,for example swing or BW
In this paper said that swing in the higher technology near that Vdd

Added after 8 minutes:

Keith is correct you definitely need a folded cascode. The JSSC paper is an improvement on a folded cascode with battery class AB output. You still need to boost the cascode to meet your 80dB gain needed if you build a 2 stage design. Are you designing for high gain low GBW? or both high. If so a three stage design will be more power efficient...

In this design must GWB and gain high and power isn't important

 

[jgk2004]

design amplifier

Well just do a folded cascode and calculate your currents needed. with gm/2piCc. then just build it. If you are shooting to high for GBW it is possible to run into a "current grave" which is you keep on put current in but you don't get any further in the GBW due to par caps increasing as well.. hense the "digging a grave" Also if your trying to hit a really high GBW check the Ft of your devices to even see if its possible...

John

 

[laperla]

Re: design amplifier

Thanks jgk
Can you give me schematic of your idea?

 

[jgk2004]

design amplifier

Go to https://cmosedu.com/cmos1/book.htm its free

then go to chapter 24 figures PPT and go to slide 44. If you dont need class AB remove the battery.

If you need boosting go to slide 51.

Hope that helps

JGK

 

[laperla]

Re: design amplifier

Go to https://cmosedu.com/cmos1/book.htm its free

then go to chapter 24 figures PPT and go to slide 44. If you dont need class AB remove the battery.

If you need boosting go to slide 51.

Hope that helps

JGK

Why do I use boosting?
why shoul I use the Boost?

 

[jgk2004]

design amplifier

To get your 80dB you wanted!

 

[laperla]

Re: design amplifier

I work with this schematic,thanks.
But I don't khnow how I can measure output swing and show it?

 

[jgk2004]

design amplifier

Hi Laperia,

If you use this design with the battery it will be class AB and hense be rail to rail output.

 

[laperla]

Re: design amplifier

No
what do I do in netlist Hspice for measure of swing?

 

[keith1200rs]

design amplifier

Just arrange is as an amplifier and sweep the input to drive the output to the rails. Or use an input waveform which when amplified will reach the rails on the output.

Keith

 

[laperla]

Re: design amplifier

Hi
thanks a lot
My professor accept that I can't give swing=Vdd and just said that we give A=10k
.for this Av can I use just cascode or I should use the 2stage OTA?

 

[jgk2004]

design amplifier

You should do a two stage design because when your output goes to the rails the gain of the last stage will be extremely small because of the transistors are going into triode. If you only use a single stage design your gain Av will drop to almost nothing when the amplifier hits the rails!

 

[laperla]

Re: design amplifier

I desinged two stage Av=80dB but GBW=120meg
How can I increase GBW?