Hello,

I am working on micropower 433,92MHz battery powered receiver and have
a problem with LNA. I have tried a few configurations (including
cascode) but I cannot lower current consumption below 400 uA. It is
too much for me. I don't need high gain because this LNA is to be a
buffer only but device price should be as low as possible. Have you
any idea how to lower the current? I don't need exact project but some
advice.

Greetings
Leopard

Hi Leopard,

What is your DC power budget, signal gain, NF etc ?

- Volts, DC
- Current, DC
- Gain, dB
- Noise Figure, dB

Might it be acceptable to switch on the LNA occasionally, but have it
sleep for 90% of the time ?

-Mark

On Jun 21, 11:39 pm, Leopard wrote:
Hello,

I am working on micropower 433,92MHz battery powered receiver and have
a problem with LNA. I have tried a few configurations (including
cascode) but I cannot lower current consumption below 400 uA. It is
too much for me. I don't need high gain because this LNA is to be a
buffer only but device price should be as low as possible. Have you
any idea how to lower the current? I don't need exact project but some
advice.

Greetings
Leopard

On Thu, 21 Jun 2007 04:39:44 -0700, Leopard wrote:


I am working on micropower 433,92MHz battery powered receiver and have
a problem with LNA. I have tried a few configurations (including
cascode) but I cannot lower current consumption below 400 uA. It is
too much for me. I don't need high gain because this LNA is to be a
buffer only but device price should be as low as possible. Have you
any idea how to lower the current? I don't need exact project but some
advice.

Please note that if you are running the LNA or mixer at very low
current, the strong signal handling will be very poor from signals at
the frequency or nearby frequencies. If you are going to run the LNA
or mixer at very low currents, I would strongly suggest that you put a
very narrow filter centered at 432,920 MHz in front of the LNA,
unfortunately the filter losses will degrade your system noise figure.

Paul OH3LWR

Hi Mark

What is your DC power budget, signal gain, NF etc ?

- Volts, DC
3V

- Current, DC
as low as possible, battery 300mAh should work minimum 1 year. Maximum
average current should be less 30uA. I wonder if this is feasible at
all?

- Gain, dB
2-3dB quite enough. My receiver is superregenerrative device and it's
sensivity is good but I have to add buffer to fulfill European RTTE
norms.

- Noise Figure, dB
This is a short range communication max 100m, transmitter has about
1mW power so the NF is less important than current consumption.

Might it be acceptable to switch on the LNA occasionally, but have it
sleep for 90% of the time ?
I thought about that. I have found such a project on EDN site. The
current consuption of the whole receiver is about 200uA but it is
still to much.