[SOLVED] Can some one explain these test conditions for a BJT's noise figure?

[Jasper Chow]

Here is a BC847 BJT datasheet from NXP. It specifies the noise figure of the BJT. But I can't understand the test conditions, especially Rs, f and B. What do the three mean, and how do they conduct this test?

 

[chuckey]

Rs is the source impedance of the test equipment = input load to transistor
f = frequency of test
b = bandwidth that the noise was measured in.
It goes like this, they put a 1K resistor on the input and measured the noise in the bandwidth of 200 HZ centred on 1KHZ this was 2-10 DB worse then measuring the noise from the resistor alone.
Frank

 

[Jasper Chow]

Rs is the source impedance of the test equipment = input load to transistor
f = frequency of test
b = bandwidth that the noise was measured in.
It goes like this, they put a 1K resistor on the input and measured the noise in the bandwidth of 200 HZ centred on 1KHZ this was 2-10 DB worse then measuring the noise from the resistor alone.
Frank

You mean they test the noise average power between 900HZ to 1100HZ , and then yield the SNR of the 1KHz signal and the 900-1100Hz noise, and caculate the noise figure?

 

[chuckey]

Yes , calculating the noise power with respect a 1K resistor.
Frank