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low power 125khz receiver
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2ndherbert:
Dear analog circuit designers,  ^-^

I am working on my thesis, the main part of witch consists of software with "minor" hardware design. I am familiar with digital design but not much into analog stuff. So far so good. My thesis includes the design of a 125khz low power, always on receiver.

What i need:
Get from 100µVpp 125khz (on-off keying with 9600bps) to the rectangular envelope signal with 3.3V (down to 2.5V).

What i have:
A very limiting budget
battery supply with 3.6V down to 2.5V at EOL
and as topping i can serve about a few µA standby current (no 125khz field)

What i came up with:
I thought about using a J-Fet in a common source configuration to get the voltages upto maybe some mV and than using a ultra low power comparator to further amplify the signal. The than rectangular 125khz signal i can rectify and feed through a loaded lowpass to generate the envelope.

What problems i have:
Finding proper j-fets for these low cutoff voltages witch are working under these low bias currents, best i can find so far is the TF412S https://www.onsemi.com/pub/Collateral/ENA2300-D.PDF
Fully understanding all the parasitic and sometimes added capacities around the common source amplifier. Are there some good design guides?

I will build the circuit this week, but i am expecting a lot of trouble since getting the circuit stable was already difficult in the simulation.

Am i on the road to hell or is there some hope?  :-//
Howardlong:
Is this RFID?
ogden:
You shall specify what you mean by "low power" and "always on". I would consider Tayloe detector/mixer based receiver. http://www.norcalqrp.org/files/Tayloe_mixer_x3a.pdf
2ndherbert:

--- Quote from: Howardlong on March 11, 2019, 09:15:17 pm ---Is this RFID?

--- End quote ---

This is not RFID. I have looked at RFID circuits but i have not found one with low power consumption.


--- Quote from: ogden on March 11, 2019, 09:33:12 pm ---You shall specify what you mean by "low power" and "always on". I would consider Tayloe detector/mixer based receiver. http://www.norcalqrp.org/files/Tayloe_mixer_x3a.pdf

--- End quote ---

With "always on" i meant that it is no option to turn the receiver off for a certain amount of time, it has to be ready all the time.

Low power means max 5µA with no 125khz signal on the receiver (i don't now when there is a field that is why i referred to "standby" and always on)
Howardlong:
What is the 100uV pp from?  Is it a tuned loop antenna?
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