Norton (inductive) feedbact amplifier designs
Does anyone know of wideband Norton feedback designs for 30-500MHz or better 20MHz-1GHz amplifiers? I tryied to simulate an amplifier based on notes from:
www.thegleam.com/ke5fx/norton/lankford.pdf
but I can't get a full 20MHz-1GHz bandwidth and also the gain is not as good a for a simple amplifier.
Does anyone know of good praktical designs with schematics for download?
Any links to designs in AWR MW Office or ADS?
I don't think you can get a very wideband amplifier with Norton type, mainly due to the inductance coupling vs frequency response, and also due to stability issues.
They work very fine in HF frequency range, and most of the professional and amateur HF transceivers (1MHz to 50MHz) use them not only in the front-end but also as IF amplifiers.
Hi,
That seems to confirm my simulations.
Then what would be the best LNA topology to go for if noise, IP3 and wideband are of importance?
Transistors like ATF54143 work fine with a resistor and a capacitor in the feedback, but resistive feedback destroys the NF and IP3 . And in this situation it is just better to go for a cheap transistor and a push-pull circuit.
Any other solutions?
Don't expect to get very low noise figure in a wideband LNA comparable with a narrow band one. Also linearity is a trade off for wide band.
Relative good compromise for a wideband LNA I got using the circuit below:
