As we know some of the components' performance will change with
temperature: e.g. amplifier. Also from the datasheet, IF switch and
digital attenuator we used also has this temperature dependency. That
could be another source of 1/f noise.
This table just summarize effect of the thermal noise to the IF system
and the requirement for temperature variance of each components.
See how the temperature change can results in 1/f noise.
Step1: For the amplifier, dGain/dTemp is calculated from the plot on
datasheet. and assume linear performance across the whole temperature
range. Here is detailed data reference:
Step2: Once we know dGain/dTemp, we can calculated the resulted SNR for
that component by this equation: calculate_SNR_from_dG_dT.pdf
Step3: here is summaried results for temperature variance requirement
for amplifiers used in the IF system:
• (reference for this calculation: MKID_Receiver_Chain_Suggested_Design_3rd_Aug_Add_Temp_Fluctuation.xls)
Other things need to note about this calculation:
* One thing to note is this gain fluctuation from temperature change
apply to both signal and noise. It does not actually reduce the SNR,
but it can introduce slow 1/f noise with temperature chagne.
* If we know d_Temp / d_time , that can help figure out where 1/f
frequency going to be: e.g. If we can control the temperature within
0.1 C, and if dTemp/dt = 0.0017 C/second (0.1 degree C per min), Then
we would see a 1/f at 0.0042Hz with around 12 dB higher than the white
* Unlike the VCO noise or amplifier used for mixer LO(those noise apply
to both transmitting and receiving side, it is possible they cancel
each other), some IF amplifier only used in the receiver chain. Its 1/f
noise might not be canceled.