[SOLVED] Fabrication of linear and non-linear devices??

[jeet_asic]

Is it possible to fabricate a device whose pull-up network is a "Resistance" and pull down network is a " NMOS gate" . Resistance is directly connected to Source of Nmos.

Since Resistance is linear and NMOS is non linear device , so is it possible to fabricate them ??? :?:





Example : Taking CMOS inverter circuit , replace PMOS gate with Resistance ####

 

[goldsmith]

Dear jeet_asic
Hi
What do you want to do , clearly ?
Do you want analyze a cmos pair ? can you tell me abit more explanation ?
Regards
Goldsmith

 

[keith1200rs]

Before CMOS, microprocessors were made with just NMOS. The NMOS load was resistive connected to the DRAIN (not the SOURCE as you suggested). In reality the loads weren't pure resistors, I believe, but resistor connected transistors.

Anyway, it is perfectly possible to use a resistive loads. A lot of microcontrollers allow you to do that. Configure the output as open drain and add an external pullup resistor.

Keith

 

[goldsmith]

Dear keith
Hi
I think using a current source at drain will be pretty better , for example a current mirror . isn't it ?
Regards
Goldsmith

 

[keith1200rs]

Goldsmith,

I don't think the question was 'what is better' but about what can and cannot be made. What he has asked can certainly be made and was the norm many years ago.

Keith

 

[jeet_asic]

Hi smith

I just wanted to know whether fabrication of linear and non-linear devices when combined together is allowed or not. If not , then why ?

i mean to say that , if i replace PMOS gate with a resistance (in an CMOS inverter circuit) and connect that resistance to VDD . I read somewhere that fabrication of "combination of linear and non linear circuits is not possible" .

Dear jeet_asic
Hi
What do you want to do , clearly ?
Do you want analyze a cmos pair ? can you tell me abit more explanation ?
Regards
Goldsmith

---------- Post added at 20:24 ---------- Previous post was at 20:20 ----------

Hey keith , sorry i forgot to add certain things , that one side of Resistance is connected to VDD and other to DRAIN of NMOS (just replace PMOS gate in CMOS inverter circuit with resistance . )

Before CMOS, microprocessors were made with just NMOS. The NMOS load was resistive connected to the DRAIN (not the SOURCE as you suggested). In reality the loads weren't pure resistors, I believe, but resistor connected transistors.

Anyway, it is perfectly possible to use a resistive loads. A lot of microcontrollers allow you to do that. Configure the output as open drain and add an external pullup resistor.

Keith

 

[keith1200rs]

Yes, that was my understanding. What I said still stands. I think the loads in old NMOS logic were probably depletion NMOS but there are probably more experienced people who can correct me if I am wrong.

With a modern CMOS process you could use a polysilicon of diffusion resistor load but you have have to have a good reason for doing it rather than simply using CMOS - a CMOS gate would be smaller, take less power and be faster with better drive and noise immunity.

Keith