Lna at-41485 Circuit diagram

[Fritzman]

Can anyone please help me with a circuit for an LNA using a AT-41485 transistor.

Here are the specs:

Frequency: 434 MHz
Active device bias point: VCE= 8V, IC = 10mA
Max Noise figure: 1,4 dB @ 434 MHz
Min Gain: 20dB @ 434 MHz
System Characteristic Impedance: 50 ohm
Vss: 12V

 

[jiripolivka]

What help you need? I would recommend to see DUBUS magazine where better designs were described in detail.
I have used a low-cost MMIC from MIniCircuits, PMA series LNAs, to get NF ~0.35 dB at 434 MHz, and ~18 dB gain. The PMA devices are directly matched to 50 Ohms i/o and need no special adjustment, operating at 5VDC, ~50 mA.

 

[Fritzman]

Thanks, Do you perhaps have a circuit diagram?

 

[rustydog747]

I need help in developing a very small receiver that can transmit signals to a transmitter within a household. (up to 20 to 50 feet) This receiver must be no bigger in diameter than a pencil eraser head and flat as paper with a sticky side. I have an idea and need someone to help and become my partner 50%/50% partnership. Goal is to press the transmitter button and hear a beeping sound from the receiver. Other goal is to get onto the show Shark Tank or mass produce this product ourselves.

 

[Fritzman]

Sounds like a spy gadget..

 

[rustydog747]

Sounds like a spy gadget..

No it's not for spying. It's for finding something that has been misplaced.

 

[BigBoss]

Look at s-parameters and Optimum Noise Impedance for that transistor, you'll find those.
Regarding to these information, design a matching circuit at 434 MHz and adjust of course biasing currents and voltages which have been mentioned being as measurement conditions in s-parameter file.
Because optimum conditions may be valid just under these measurement conditions.

 

[jiripolivka]

Thanks, Do you perhaps have a circuit diagram?

Please look on PMA series LNAs on "www.Minicircuits.com". There are all specs including a test board. There is in principle no "schematic". The MMIC has two ground pads, input and output that need to insert small SMD 1-nF capacitors, and a resistor from output pin to +Vcc, 3.3 to 5.0 V. This is all.

Nothing to adjust, simply put it on a board and you have a wonderful LNA with 0.3 dB NF at 434 MHz.