How to analysis this circuit?

[isaacnewton]

How to analysis this circuit? What's the advantage and disvantage of the circuit? Especially, the circled part.

The circuit is copied from Razavi's book. Page 132, Figure 4.39.

 

[sgupta_one]

Refer to book by Milman & Grabel

 

[isaacnewton]

I don't have this book.

Refer to book by Milman & Grabel

Added after 3 minutes:

Could you just give me a hint? Thanks.

Refer to book by Milman & Grabel

 

[pixel]

I would say latch...
small circuit ressistance of this block is -2/gmp.

 

[aland]

Differential Driver with current control( or Enable), Vout will toggle polarity.

 

[windgone0204]

It is a passive feedback in the comparator circuit which can emprove the speed performance.You can refer it to Allen's book.p471

 

[shaq]

Just draw a small-signal model, you'll get the negative resistance of them.

 

[Davood Amerion]

M1, M2 makes comparator, and M3, M4 make hystersis for this circuit (schmitt trigger).

 

[hb_cancer]

Hi there !
Well if you observe the book, the reasoning is as follows or infact try reasoning them yourself step by step:

1. What is the need for an amplifier ?
2. What is the advantage of having an amplifier in Common Source(CS) Configuration?
3. How can the gain of the CS amplifier be improved or infact varied?
4. If gain can be varied by Rd resistance, then it could be logical to have a very large value of resistance at the drain, so what are the types of load resistances possible?
5. If a Mos Transistor is chosen as load then what are the advantages it provides in order to improve the gain ?
6. What if the gain is acheivable, but the gain is not constant or varies with the supply voltage, so, whats the need for source degenetration?
7. All the above were wrt a single stage amplifier but, what is the advantage of a differential amplifier design?
If you could justify correctly the reasons for the above Questions you will clearly understand the need for the Highlighted transistors.
Hope this is of any Help to you. If there are any further queries post them here...

 

[isaacnewton]

The up figure - when (Vin1-Vin2) sweeps from -1.5 V to 1.5 V.
The bottom figure - when (Vin1-Vin2) sweeps from 1.5 V to -1.5 V.

M1, M2 makes comparator, and M3, M4 make hystersis for this circuit (schmitt trigger).

 

[shake2004]

referring to allen's book about the comparator or any digital circuit design book

 

[walker5678]

It is the positive feedback which improve speed performance.

 

[rfic]

You can refer it to David John's book.

 

[teteamigo]

Simple:

Vout switchs M3 or M4 to triode.

Comparator.

 

[fanrong]

I would say this is a amp with positive feedback or a comparator with hysterysis .

 

[beckchm]

resistence is negative , but positive feedback

 

[fashion]

It is a positive feedback, and sometimes use it as latch function.

 

[rob1012]

Hello...

i think that is a gate cross connected load used to speed up switching times.. When output at one side falls to a level that triggers one PMOS load on, output on the other side quickly goes VDD or approximately VDD-Vthp..