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Post subject: measuring The Noise Figure of WLAN Receiver RF Front-end
Posted: Thu Jan 21, 2010 7:31 am
Joined: Wed Aug 16, 2006 8:20 am
I want to measure the Noise Figure of the RF Front-end (Switch+LNA+Diplexer) for a WLAN receiver implemented using Discrete components.
I don't have a Noise source and Noise Figure meter to chatracterize the Noise Figure of this assembly. I was thinking of trying the following approach.
1. Since I don't have a vector signal generator, I will use a WLAN transmitter that I designed. Attenuate the output power to -60dBm (burst power). Feed this signal to a Vector Signal Analyzer and measure the EVM. Let us call the EVMin
2. Remove the VSA and connect the RF Receiver Front-end. This will feed the Transmitted signal at the antenna port of the Receiver. Now at the other end of the receiver chain connect the VSA and record the EVM. Let us say that this is EVMout.
3. Can I assume that the EVM will be proportional to the SNR at low input power levels. if yes, then can I use the difference between EVMin and EVMout as an estimate of the Receiver RF Front-end Noise Figure.
I will be trying this out in the LAB. If anyone finds any fault in this method thebn please share your thoughts.
Design Engineer- RF