[sergey23 0]

Hello ,I used a method shown in the circuit below to bias Vg1 input of PMA5-83-2W link below.
I assumed my Vg1 input is high Z so 1 put 1Mohm resistor as the load for the circuit you helped me to build.
Is it a correct assumption?
Ltspice files are attached.
Thanks.

https://www.minicircuits.com/pdfs/PMA5-83-2W+.pdf




 

 

 

test.zip

Изменено 11 сентября пользователем sergey23

[_Sergey_ 20]

If you look at the datasheet you will see the gate current (IG1) may reach up to 4000uA.

With typical gate voltage (VG1)=-0.8V it gives us 0.8/0.004 = 200 ohms resistance.. not 1M.

[sergey23 0]

Hello Sergey,I understand that the value of the load is irrelevant.

Whats relevant is the ability of the circuit bellow to sink current while keeping the desired -2.5V
When I swept RLoad for different value and i see that at some Rload values i get 8mA(twice the maximal rating) 
How do i know that it will get enough current from my reference regular source ?

LTspice files are attached.
Thanks.
test.zip

 

Изменено 11 сентября пользователем sergey23

[1113 9]

add 4,7 uF capacitor as load

[sergey23 0]

Hello ,We supply from the anode -2.5V.how can I see the current sinking capabilities of this device when its -2.5V
in the datasheet?
Thanks.

https://www.ti.com/lit/ds/symlink/tl431.pdf?ts=1726014140885&ref_url=https%3A%2F%2Fwww.google.com%2F

Изменено 11 сентября пользователем sergey23

[_Sergey_ 20]

Sorry.. but sometime i think you make a fun here.

I didn't have a deal with PMA5-83-2W ever and i don't know it's working conditions.

On your schematic i see U2 that acts like a voltage source and a voltage divider wich is formed by R6 and Rload.

Iload is limited by R6 and U2 (TLV3701) only.

TLV3701 has maximum output current +/- 10mA that is bigger than twice Ig1=4.5mA. By the case pay attention to TLV3701 power supply.  By the datasheet it is +/- 8V only.

U1 acts like a zener diode. The one has a dynamic resistance. This means one's sinking current depends on an applied voltage. Look at the figures 6-3 and 6-4. After appiled voltage reaches 1v the sinking current starts rising gradually and at 2.5v goes up vertically. According this plot U1 may sink more than 100mA.

As you wrote upper you need 2.5V at the load. Ok. (8-2.5)/1000 = 5.5mA. That is bigger than 4.5mA. 1mA extra current will be sinked by U1.

[sergey23 0]

Hello Sergey,Yes you are correct this is my main dilema because i need at most 4.5mA but my TLV3701 can supply twise the amount.

It all depends on the load of the curcuit .If i want Vg1 to have -2.5V and 4.5mA then i need to pray that my PMA5-83-2W+  load will be 2.5/0.0045=555 Ohms.

But i dont know what load my sequencer circuit will see from the device.

What do you reccomend the avoid the situation of burning it?

 

https://www.minicircuits.com/pdfs/PMA5-83-2W+.pdf

On your schematic i see U2 that acts like a voltage source and a voltage divider wich is formed by R6 and Rload.

Iload is limited by R6 and U2 (TLV3701) only.

TLV3701 has maximum output current +/- 10mA that is bigger than twice Ig1=4.5mA. By the case pay attention to TLV3701 power supply.  By the datasheet it is +/- 8V only.

Full LTspice circuit is attached.
 

test.zip

Изменено 20 сентября пользователем sergey23

[sergey23 0]

Hello , I have started to build the PCB.one dilema I have regarding the capacitors at the ports of the amplifier.In the datasheet they asume we switch voltage sequence manually.
But in our case we have built a sequencer.
How in real life lab you reccomend me to see if i need load capacitors at Vg1 Vg2 Vdd?
https://www.minicircuits.com/pdfs/PMA5-83-2W+.pdf