433 Mhz receiver/amplifier help!!

Hi, i'm working in a wireless sensor project and I have to design and build a small, low-power receiver for 433 Mhz.
I found a couple of circuits in the net but I'm kind of lost, what I need is to select a right antenna (small size and indoor range about 30 ft, maybe less), and to build an amplifier. For that i was thinking in using the envelope detector, and then a digital comparator (like a max9119) so that way I sould be able to use that signal at the input of my sensor. I don't know if this is a good idea, or which components do i have to use. Thanks for your help!

PD: I can only use a 3V small battery for my design!

What experience do you have with RF and analog? Are you planning to use off the shelf RX/TX modules? If not, your in over your head. Sorry to be blunt but stick with something in your range of know how.

Hello, well actually I'm working in a "low-power radio-triggered wake up" for wireless sensors... I really don´t care about eht transmitter since it´s not going to be placed in the sensor (not for this frecuency, but for 2,4 Ghz). So I just need to be able to send a signal @433 Mhz... and with the envelope detector turn it to a "wake up signal" (digital "1") to interrupt the sleep mode of the sensor. And yes, I don´t have experience in RF, but i have to do this and need some help

If you are determined to build this, you could use an IC like this one:

https://www.electro-tech-online.com/custompdfs/2009/03/micrf007.pdf

Be sure to copy the circuit board layout given on page 12 exactly and use the component values that they specify in the BOM.

sorry i think I didn't explain well what i was thinking to do. My main problem here is the power consumption, and since I need the receiver to be turned on all time (no pooling), I need It to be as simple as possible. I don´t have experience with RF, but if the antenna can recieve a OOK at 433 Mhz, With a envelope detector I shoult be able to turn this signal digital, by using a comparator with a specific threshold. Actually i don´t need to recieve INFORMATION, since this is only a wake up circuit... I only need to interrupt my cc2430 to turn it on. I saw a design in internet it is composed by:

1. impedance acoplator (for deliver maximum power from the antenna)
2. Voltage multiplier (5 stages)
3. A comparator with a resistor in one input (with the signal from the antenna), and a divisor in the other (voltage reference)

For the author it is suposed to work to get a digital signal, but it doesn´t say at wich frecuency or anything...

I thought that 20mW was not a bad power consumption (for the Micrel example linked above) so I'm wondering how low you are looking for.

This one is simple but it isn't obvious what the current consumption would be:

https://jap.hu/electronic/rf/rf_daughter_board.jpg


Here are some more useful links:
RF circuits

Some problems you may face in your design:

- if you attempt to have very high sensitivity then you will put in a lot of amplifier gain and in this case you will find it difficult to keep the system stable. Voltage gain of 5 times is modest and will probably be OK.
- interference always limits the performance of a receiver and the way to eliminate interference is to include a bandpass filter to allow only your signal through.

20 mw is a lot if we´re talking of 3V button batteries.. the design i saw used resists and a simple comparator, it consumes 2,45 Microwatts (two resists in the range of Mohm and a MAX9119 with a 3V supply consume 876nA). Check out page 3.. I'll do some like that... but not for a telos. It´s almosto passive!

sorry I forgot the link
https://www.electro-tech-online.com/custompdfs/2009/03/RTWAC-PIMRC-2008.pdf

I did not read too far into the paper, but I get the idea. Yes, it is almost passive indeed! At a range of only 10m I was disappointed that the idea isn't breaking new ground for increased range, as I have an RFID invention that is still waiting for more range. This kind of range is just above the kind of distances one can get with passive tags at UHF and L band frequencies. They communicate in two directions, which is a greater challenge than your example.

At this small range, my concerns about interference are small. It is interference that often drives receiver architectures to greater complexity and greater power consumption. In your paper, the only selectivity in the system is in the antenna and its matching network, so it will trigger from almost any strong signal that comes close. I hope that isn't an issue for you. With a bit more power you can improve a lot on this.

I saw another paper just a day ago that you might be interested in. It discusses the results of experiments to harvest energy from ambient RF power in order to power things like your receiver. They are collecting 60 microwatts and up out of thin air. They use a diode multiplier circuit (charge pump) almost exactly like the one in your paper, only it feeds a power accumulation circuit. I think you need to use something like that. Unfortunately, it often comes down to the antenna, its tradeoff of size vs gain and frequency band. But it can be done. Perhaps this could be used to supplement a rechargeable lithium button cell.

As your paper discusses, there are great benefits to be had from duty-cycling. Can you consider turning your wake-up receiver on and off with a short period, in order to save even more power? Or does it really have to be on every single millisecond?

hi! I have been having some problems lately.. but now i'm back to work!.. i have my circuit builded... schottky diodes, capacitors, splatch antenna by linx I'm testing it with a aurel 433 transmitter.. but the range is way shorter than what I expected (consider too that for the first test I'm using a peace of cable as antenna, I ordered a transmitter with integrated helicoidal antenna).

I have chequed everything and i realized I forgot to put some vias to groundplane in the PCB between each pad for the antenna :S I'll make those vias and I'll tell you how is it going..

So far the power consumption is extremely low.. I'm trying to measure current with a source that has 0.01 mA of resolution and I have not being able to do it.. I have calculated the current by measuring the voltages in each resist. and trust in the comparator's datasheet...

Menawhile I'm learning how to program the CC2430 SoC, which I will use to make my demostration... Talk to you soon!

Super-regenerative receiver can be very low standby power.

270 µA is the lowest consumption i've seen around different projects...
this one es 0.88µA , there is a difference.