Hitachi PF08109B power amplifier circuit design

[harishyadav]

Dear sir,
I am using Hitachi PF08109B power amplifier.
i am providing Vapc (Pin no. 10,Max. ratings: 2.2V , 3mA) to the Power amplifier using a voltage divider circuit.
The open circuit voltage is set to 2.5 but once connected it drops to .9V dc.
Is it a current consideration ?
Why the voltage is dropping when connected in the circuit?

 

[Audioguru]

You forgot to post its schematic.
What is the function of Vapc?

If you load a voltage divider then its voltage normally drops unless the current in the voltage divider is much more (>10 times) than the load current. Then what was the current of your voltage divider?

 

[harishyadav]

You forgot to post its schematic.
What is the function of Vapc?

If you load a voltage divider then its voltage normally drops unless the current in the voltage divider is much more (>10 times) than the load current. Then what was the current of your voltage divider?

-Reply from harish :


Dear sir
i have posted an image of the circuit in which power amplifier PF08109B is used .
The pin of my concern is pin Vapc(GSM) (control voltage, Pin no.10).

 

[KlausST]

Hi,

Your voltage source from the pot is weak.
A 10k pot has an output resistance of 0...2.5kOhms (in your configuration).

The datsheet doesn't say the input current is constant, therefore I sassume it varies.
If it varies from 1mA to 2mA...this may cause a voltage drift of 2.5V.

--> I'd use an amplifier to generate a low impedance voltage source.

Klaus

 

[harishyadav]

Hi,

Your voltage source from the pot is weak.
A 10k pot has an output resistance of 0...2.5kOhms (in your configuration).

The datsheet doesn't say the input current is constant, therefore I sassume it varies.
If it varies from 1mA to 2mA...this may cause a voltage drift of 2.5V.

--> I'd use an amplifier to generate a low impedance voltage source.

Klaus

Reply from harish yadav,




Dear sir,
As suggested by you,
Please suggest a suitable circuit of an amplifier generate a low impedance voltage source .

 

[KlausST]

Hi,

almost any "non inverting OPAMP circuit" will do. Gain = 1.


Klaus

 

[Audioguru]

Many opamps do not work from a low power supply voltage and have inputs and outputs that cannot go down to only 2.2V.

 

[harishyadav]

Dear sir,
I am using RF section circuit (attached below) in my Mobile jammer project:

1. I am not able to find "50 ohm Micro strip" that is used for impedance matching.Please suggest a solution for "50 ohm micro strip" or any other alternative for impedance matching.

2.Which online RF circuit simulation tool is good in order to check the circuit output?

 

[Audioguru]

A Mobile (cell phone) jammer is illegal (it will block somebody calling for an ambulance, a fire brigade or calling the Police) so we should not help you with it and this thread should be closed.

 

[KlausST]

Hi,

The thread is going into a wrong direction.

We don't want to support the design of illegal circuits.
Therefore we decided to close the thread.

 

[harishyadav]

PF08109B power amplifier

Dear sir,
This is my final year academic project. i have no such planning as quoted by you.
This is only for academic purpose.
The same problem i had with Modem Design.
Rest assured that i have no such intentions.

 

[FvM]

O.K. Thread re-opended. Please no further discussions about GSM jamming, e.g. technical details how to achieve it.