mtwieg
Advanced Member level 6
A while back a made a thread about my attempts to get the specified NF out of a AD8331 LNA. That hasn't worked out (despite consulting with a AD application engineer), so I guess I'm going to need to roll my own discrete LNA.
My application is narrowband (maybe 200KHz) with a center frequency between 7-15MHz (not sure yet). I'm hoping for a NF less than 1dB from a 50 source (though I will need some impedance transformation at the input).
Right now I just want to get an idea of what technologies would give good NF at such frequencies. I'm looking at GaAs Fets, dual gate silicon FETs, HEMTs, etc, but none of them are specced below 100MHz. Also before anyone suggests it, I don't have access to good simulation software like ADS or Ansoft.
Also, I've been preemptively investigating methods for noise characterization, but am still unsure how to approach this. I have access to a good signal analyzer with a NF measurement setup, and a decent network analyzer. Do you think it should be necessary to measure the input referred noise currents and voltages, then calculate my noise impedance and match to that? Or should I just try and find the optimal reflection coefficient by trial and error?
Thanks in advance.
My application is narrowband (maybe 200KHz) with a center frequency between 7-15MHz (not sure yet). I'm hoping for a NF less than 1dB from a 50 source (though I will need some impedance transformation at the input).
Right now I just want to get an idea of what technologies would give good NF at such frequencies. I'm looking at GaAs Fets, dual gate silicon FETs, HEMTs, etc, but none of them are specced below 100MHz. Also before anyone suggests it, I don't have access to good simulation software like ADS or Ansoft.
Also, I've been preemptively investigating methods for noise characterization, but am still unsure how to approach this. I have access to a good signal analyzer with a NF measurement setup, and a decent network analyzer. Do you think it should be necessary to measure the input referred noise currents and voltages, then calculate my noise impedance and match to that? Or should I just try and find the optimal reflection coefficient by trial and error?
Thanks in advance.