Substrate choosing for 0.5 GHz to 2 GHz low noise amplifier design
I have designed the low noise amplifier at 2 GHz. Now I am in confusion, which substrate I need to choose for "BEST PERFORMANCE" of circuit after PCB manufacturing results.
Which one I need to use for best performance,whether I have to go for FR4 or ROGERS RT/DUROID 5880.
I have gone through many previous posts regarding on the substrate selection. Some are telling that upto 2GHz, FR4 will give you the best results.Some are telling that FR4 will not be good for best result expectation. For best results, you must have to go for the ROGERS RT/DUROID substrate.
For simulation of 2GHz LNA design, I have used the FR4 substrate, now I have to go for the PCB manufacturing . I am in confusion which substrate I have to choose for best results.
I need best results after the PCB manufacturing, can you anyone advice to me which substrate I need to choose , why we need to choose that substrate.
You have to define for your case the "best performance" of the LNA.
For example between 0.1dB and 0.5dB noise figure, is the same hard task to design as between 1dB and 5dB noise figure.
If you are looking for an "average" noise figure of 0.5dB, FR4 would be the best compromise up to 2GHz.
It all depends on the accaptable increase of noise figure (or noise temperature).
If you have an LNA with F=0.2 dB (Tn = 14 K), and for example a source with very low noise temperature (antenna looking into space), 0.5 dB loss because of a microstrip on FR4 (room temperature) can be unaccaptable. your Tn increases to around 48 K.
If you have a room temperature source, then the 0.5 dB loss will likely not be a problem.
vfone Sir,
I am looking for the average noise figure as < 0.5 dB , which substrate I have to choose , it must be low cost and best performance . If we go for FR4, which company and series FR4 (Like ARLON, ISOLA, NETLAC/NELCO). Otherwise if we go for rogers company which series I have to choose to obtain < 0.5dB NOISE FIGURE average or at particular frequency from 0.5GHz to 2GHz.
I must need substrate low cost and also as well as best optimum performance of noise figure.
Noise is almost independent from substrate because noise is dominantly generated active and passive elements in the circuit.
Substrate metals' ohmic losses can contribute into these noise source but they are relatively very low and almost negligible since your matching elements have negligible dimensions.But if you intend to design a PCB coil to make this LNA low noise ( Noise Match ), in this case Eddy Current losses will decrease the Q factor of this coil and consequently this will be appeared as a parallel equivalent resistor across the coil and it would also create a noise source but as I said before, dominant noise sources are internal.FR has been used in many applications for this kind of LNA.
But nevertheless, to decrease the external matching elements' dimensions ( less ohmic and substrate losses) use a high di-electric coefficient substrate.
Dear Sir,
For practical implementation and PCB manufacturing in the range of 0.5 GHz to 2 GHz design of LNA, which company and which series FR4 and RT/Duroid will give low cost and optimum performance. Can you advice me.
Dear Sir,
"Best performance" of the LNA, it means, whatever we are simulating S-parameters, and noise figure (NF). After PCB fabricating measured values must be well matched with the simulated values.
Rogers RO4000 series it is a very good compromise for high quality microwave design.
http://www.rogerscorp.com/acm/produc...Laminates.aspx
The substrate quality would affect the noise figure of a microwave LNA for values of NF<0.5dB. As I mentioned, between 0.1dB and 0.5dB NF, it is a very long way in LNA design.
Dear Sir,
Previously I searched postings regarding on the substrates, they are also suggesting the Rogers 4000 series for low cost and quality performance.
Doesn't FR4 give quality performance < 0.5 dB noise figure of LNA from 0.5 GHz to 2 GHz.If we choose FR4 in this range (ARLON, ISOLA, NETLAC/NELCO) for quality performance with low cost, which series and which company is good.
One more doubt I have , Rogers R04003C and RO4350B will they have same low cost as like FR4 substrate.No doubt about Rogers company quality performance, I am worrying about the cost. If their cost is low, we can think about go for choosing as like FR4 substrate.