hi
i have a signal at the output of quadratur LNA,i do need to Combine this signal and increas signal noise ratio of that at the output signal.
pleas anyone has any schematic for that???
Try with a quadrature hybrid circuit like a branch line hybrid combiner. Signals will sum in voltage and noise in power (sqrt(2) increase over SNR).
Bye Mrm
try my previous suggestions: noise are uncorrelated and sum by power. Signals are correlated and sum by power. It's the principle of diversity receiption.
I presume you are talking about a receiver signal to noise ratio. What you need to concern is the front end circuit of the receiver. As flatulent explained, use lower noise figure amplifier as front end LNA. Try using lower insertion loss bandpass filter (if necessary) before LNA.