Help with 433.92Mhz miropower receiver

Hi,

I want to built 433.92Mhz RF wake up receiver with minimal power requirements (below 40uA with amp).
This receiver have to do one thing: detect wake up signal and wake up main receiver. Operting range that I need is reliably 7 meters. output power of calling signal is 10mW max. (TX=QAM-TX3)

I thought that I searching whole net to get some information about it and download thousand of PDF's but till today not made It. I reached weak 2 meters of distance with HSMS 2850 detect diode and max9917 amplifier.

I have poor knowleadge about electronic design..so then, can I say that about RF know nothing...

Can I design RF circuit on breadboard? When I made PCB from circuit on breadboard it absolute don't worked. I don't know make design good working RF PCB.
So can You advice me about diode detector's to solve this great problem for me? tested PCB layout I very, very appreciate...
thanks

Not the kind of thing you can easily build yourself. As for 40uA and breadboarding not likely.
**broken link removed**

igorhtm said:

Hi,

I want to built 433.92Mhz RF wake up receiver with minimal power requirements (below 40uA with amp).
This receiver have to do one thing: detect wake up signal and wake up main receiver. Operting range that I need is reliably 7 meters. output power of calling signal is 10mW max. (TX=QAM-TX3)

I thought that I searching whole net to get some information about it and download thousand of PDF's but till today not made It. I reached weak 2 meters of distance with HSMS 2850 detect diode and max9917 amplifier.

I have poor knowleadge about electronic design..so then, can I say that about RF know nothing...

Can I design RF circuit on breadboard? When I made PCB from circuit on breadboard it absolute don't worked. I don't know make design good working RF PCB.
So can You advice me about diode detector's to solve this great problem for me? tested PCB layout I very, very appreciate...
thanks

Click to expand...

Your attempt to detect using the HSMS2850 plus an op amp is probably the best way to solve the problem. 40 microamps is not really enough to realize any RF amplification or other signal processing at 433 MHz, so you are stuck with using a passive RF detector (the diode) and some baseband gain (the op amp). To make this as sensitive as possible, you should do two things. One is to add a small DC bias current to the detector diode to move its operating point closer to the diode knee voltage. A bias current of a few tens of microamps might be enough to be useful. Second, you need to use a very good antenna to couple the most 433 MHz energy into your detector. And this coupling must be done with careful impedance matching to avoid unnecessary losses.

You must understand that such a detector is not selective other than that which the antenna provides. So it may trigger from any nearby RF sources.

Thanks for response blueroomelectronics and RadioRon,

Micrel super-heterodyne receiver consume 6mA..

I'm able to add DC bias to this receiver! In datasheet for HSMS285 diode:

**broken link removed**

wrote that detector with DC bias of some microamps can reach sensitiviti as high as -55 to -67 dBm what is approximately 10nW of power level. Next I plan to use SAW filter to supress any other frequency except 433.92Mhz. (this will cost 3dBm of power loss)

look at this interesting link:

https://www.electro-tech-online.com/custompdfs/2008/12/2007-11-sensys-121-revised.pdf

or this: https://www.electro-tech-online.com/custompdfs/2008/12/wakeup-radio.pdf

and now I currently do this RF diode detector: A Diode Sensor for RF Power measurements but I must exactly keep and simulate this PCB layout!(look on graph how good DC response can be reached)


I study this projects and think that is possible to made such RF wake up receiver with good performence (10 meters) and with SAW filter, but It's close to impossible when trying it man with minimal RF experience.. so, some another diode detector scheme or PCB layout will be very helpful..