[sergey23 0]

Hello ,The main goal is to Bias the CGHV1A250F transistor which is represented as 3 Ohm load resistor.shown below using PMOS shown below datasheet and spice model.LTspice file is attached with the imported spice model of the PMOS.
I know the conditions for opening PMOS and NPN shown below.
Suppose my pulse is in ON state.

Given the diagram below,what is the strategy for formulating the current that will be flowing threw as a function of NPN and PMOS expressions?
So i'll know what is the role of each element an how it influences the current going into the load resistor.
Thanks.


https://pdf1.alldatasheet.com/datasheet-pdf/download/1673867/WOLFSPEED/CGHV1A250F.html

PMOS:
https://eu.mouser.com/ProductDetail...T*MTcxNDkxNTc1My4xLjAuMTcxNDkxNTc1NS41OC4wLjA.

PMOS spice model:
https://www.vishay.com/doc?76129

new_model.asc

[1113 5]

походу ИИ какого-то пылесоса дорвался до интернета и решил изучать схемотехнику на этом форуме

[sergey23 0]

general strategy will also be good.

UPdate:

The circuit is like this:

 

[1113 5]

design of schemes has long been studied and formalized. To calculate the circuit you do not need to delve into the mathematical jungle. it is possible and necessary to move to higher levels of abstraction. have you tried counting electrons?

[sergey23 0]

regarding PNP i know that  V1=I1*R1+Vbe so i could know what is the Base current then i'll take beta value and  I_c=(beta+1)*I1.
Any clue how to climb from this to the PMOS logic?

I suppose i want PMOS to bea voltage source for the load.
How can i calculate the current threw PMOS?

Thanks.

 

Изменено 5 мая пользователем sergey23

[1113 5]

PMOS is controlled resistor with Ron = (4,6 to 7,5 mOhm). see siss65dn datasheet. so your output stage will transform to simple resistor divider 

[sergey23 0]

the resistor around the pmos have some logic i want to find matemaical expression for PMOS drain current.

[1113 5]

15 minutes ago, sergey23 said:

the resistor around the pmos have some logic i want to find matemaical expression for PMOS drain current.

check this https://inst.eecs.berkeley.edu/~ee105/fa03/handouts/lectures/Lecture12.pdf

[sergey23 0]

Just for the sake of knowledge i want to solve mathematickly the circuit i posted.
I am trying to solve the equations for PMOS current threw the drain.
A drawing of the currents on diagram shown in the attached photo.
Von suppose its 5V for mathematical purposes
how do i know the voltage potential at the collector of the bjt? so i could find the voltage at the gate of the PMOS afterwards
Thanks.
Von-Ib*R3-Vbe=0
Ib=(Von-Vbe)/R3
Ic=beta*Ib=beta*(Von-Vbe)/R3
20-(R1+R2)*Ic=V_bjt_collector
Also i know that R1 is a sort of discharge for mosfet gate capacitor

[sergey23 0]

update:
 

when i am openning the NPN in saturation mode the gate capacitance start to discharge towars the zero.
but there is a 20V source which tries to charge it back to 20V threw R1.
sowe will get that a current will flow from 20V source to the gnd of the NPN.
NPN is in saturation  so according to the data sheet i'll have some Vce at 100mA

https://www.mouser.co.il/datasheet/2/916/BC848_SER-2937561.pdf

[тау 29]

4 часа назад, sergey23 сказал:

Ic=beta*Ib=beta*(Von-Vbe)/R3
20-(R1+R2)*Ic=V_bjt_collector

[sergey23 0]

Both Yes, thank you very much Tay 🙂
There are two case which I want to analyze.

the first case when the PMOS gets open  basically it get discharge from ground.
My PMOS is SISS65DN, what voltage so i need to put on my source?

also for CGHV1A250F transistor , i am not sure what voltage i need to put on its drain? 

https://pdf1.alldatasheet.com/datasheet-pdf/download/1673867/WOLFSPEED/CGHV1A250F.html
 

SISS65DN.PDF

[тау 29]

13 минут назад, sergey23 сказал:

also for CGHV1A250F transistor , i am not sure what voltage i need to put on its drain? 

 

19 минут назад, sergey23 сказал:

My PMOS is SISS65DN, what voltage so i need to put on my source?

The maximum voltage for V2 can be   max  30 V !!!

[sergey23 0]

Hello  Tay,quecent current is when there is no RF signal going at the gate.when we put smal signal(rf) at the gate i current will rise because its a property of transimpence.

Can you see what current the amplifier will experience when its actually amplifying a signal and not just in quecent mode?

 

Also can you recommend maybe similar power PMOS mosfet which could suite CGHV1A250F?

Thanks.

[тау 29]

11 минут назад, sergey23 сказал:

Can you see what current the amplifier will experience when its actually amplifying a signal and not just in quecent mode?

see please fig. 20 from CGHV1A250F – Specifications

12 минут назад, sergey23 сказал:

Also can you recommend maybe similar power PMOS mosfet which could suite CGHV1A250F?

this is very simple: