output noise level calculation of RX chain given only data sheet - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: February 05, 2025, 04:23:16 pm
content: Hello, I have an RX system shown below where my signal goes threw amplifier mixer and then filter and another amplifier .Friss formula is not relevant im my case .the boltsman formula Pnoise=-174dBm+10log(BW)given the datasheet below How can I know the noise level in the end?Thanks.https://www.qorvo.com/products/p/TGA2227https://markimicrowave.com/products/microstrip/mixers/m1-0818ne-1/datasheet/https://www.minicircuits.com/pdfs/ZRL-700+.pdf?srsltid=AfmBOooUiQy2hNcdwjar5kAFbhmyih9wNintJh3AEZKXgaVbp7fCCEcH

author: rfclown
author_rank: Frequent Contributor
timestamp: February 05, 2025, 04:41:02 pm
content: I use cascaded NF formula (Friis). For the mixers I use NF=conversion loss.

author: john23
author_rank: Frequent Contributor
timestamp: February 05, 2025, 04:50:14 pm
content: could you show the calculation you make using the three components i have shown?Thanks.

author: rfclown
author_rank: Frequent Contributor
timestamp: February 06, 2025, 04:41:03 pm
content: You have more than 3 components. Every item is included in the cascade analysis. RF switch + TGA2227 + circulator + mixer + LPF + HPF + ZRL-700 etc. If any of the interconnect lines are long, include losses for those also. Find a cascade analysis spreadsheet and enter gain and NF for each item. There are at least 15 items.

author: mtwieg
author_rank: Frequent Contributor
timestamp: February 06, 2025, 05:43:39 pm
content: Agree with rfclown, just tabulate the power gain and noise figure of each stage (for passive stages can approximate NF=G in dB). Plug it all into the Friis formula.Only interesting part is that you have a polyphase output. You can treat each output independently and the Friis formula will give you its NF, G, and output noise level, but if you want to look at it as one complex output then the math must change a bit...

author: john23
author_rank: Frequent Contributor
timestamp: February 06, 2025, 07:36:31 pm
content: Hello , So If I understand correctly we take the minimal BW(which is the filter limitation) it gives us the starter -174dBm+10log(BW) as shown in the photo below.after each stage we do we add gain and NF as shown bellow.few questions:1. So after TGA_2227 using the calculation -274+10log(BW)+NF+gain in the photo I got -185dBm is it correct?2.When we are using a mixer it downconverts non desired products which ruins also the SNR.Could you give me an example how you calculate these additional factor in M1-0818NE-1 mixer?Thanks.https://markimicrowave.com/products/microstrip/mixers/m1-0818ne-1/datasheet/

author: mtwieg
author_rank: Frequent Contributor
timestamp: February 07, 2025, 12:38:09 pm
content: Quote from: john23 on February 06, 2025, 07:36:31 pmPersonally I would carry out the calculation of total gain and noise figure first. Then you can calculate total noise output power as Pout = Pin + G + NF + log10(BW), where Pin would be -174dBm at 25C.QuoteYes if you don't have anything preventing noise at image frequencies from contaminating your IF, then this will degrade your noise figure. For example if the noise at the RF port is wideband (equal at all frequencies) then you should expect a 3dB penalty to noise figure. Which is why you really should have a bandpass filtering on the RF port!

author: john23
author_rank: Frequent Contributor
timestamp: February 07, 2025, 04:38:10 pm
content: Hello ,I am trying to collect the pieces of the mixer from the datasheet.Assume that the output of the TGA2227 is the input of narda0818 ,so the pieces of data I have is are as following:input noise from TGA2227: -174 + 10*LOG(2*10^10) + 2 + 15 = -53.9dBm.Noise figure of a mixer is 0.5dBm (above 5 MHz)The conversion loss is 6 (gain =-6)BW of mixer is 10GHzIIP3 is 18dBm,OIP3=IIP3+component gain (conversion loss) so OIP3=18-6=12.Two questions:1.What is the formula you use to peace of these data peaces into the output noise?2. I know that compression in the third order on the output is a big problem.but the mixer might not be compressed ,the OIP3 might be located at far away places. Why do you take it into account when calculating the output noise?The input IP3 or IIP3 is simply the OIP3 minus the gain of the amplifierhttps://markimicrowave.com/products/microstrip/mixers/m1-0818ne-1/datasheet/

author: john23
author_rank: Frequent Contributor
timestamp: March 27, 2025, 12:45:17 pm
content: Hello , following the method you thought me , I have tried to calculate the SNR of my RX chain.Full calculation is shown below with the diagram and relevant properties of each component on the chain in the photo below.Also I have described in the video in the link below called "2025-03-27 14-09-07.mkv" the logic of my calculation.Did I implemented properly the method you described?Thanks.https://technionmail-my.sharepoint.com/personal/yefimv_technion_ac_il/_layouts/15/stream.aspx?id=%2Fpersonal%2Fyefimv%5Ftechnion%5Fac%5Fil%2FDocuments%2FTemp%2F27%5F03%5F25%2F2025%2D03%2D27%2014%2D09%2D07%2Emkv&referrer=StreamWebApp%2EWeb&referrerScenario=AddressBarCopied%2Eview%2E385ffd13%2D0b9b%2D44d6%2D81e7%2D3bc490c77824noise from A5 to the output (dBm/Hz):-174+NF(A5)+Gain(A5)+Conversion loss(M3)+mirror(3dB)+IL(HF+LF)+gain(A6)+NF(A6)+gain(Att1)+gain(A6)+NF(A6)+gain(Att1)+IL(SP_C_0)+convertion_loss(M4)+IL(BPF1)+gain(A7)+NF(BPF1)==-174+1.8+15-8-0.5+3-0.9+28.6+1.4-3+28.6+1.4-3-4-6-1+24+5.1=-91.5 dBm/HzBPF1 BW=225MHz ->10*log10(225*10^6)=80dBNoise in dBm:-91.4+80=-11.4dBmsignal on output:-60+15-8-1.4+28.6-3+28.6-3-4-6-1+24=9.8SNR=9.8-(-11.4)=21.2dBA5:https://www.analog.com/media/en/technical-documentation/data-sheets/hmc772.pdfM3:https://markimicrowave.com/products/surface-mount/mixers/mm1-0320hsm-2/datasheet/HF:https://www.minicircuits.com/pdfs/RHP-147+.pdfLF:https://datasheets.kyocera-avx.com/AVX-MLO_LP-Filters.pdf#page=8ATT1:https://www.qorvo.com/products/d/da001056M4:https://www.minicircuits.com/pdfs/MCA1-24MH+.pdfSP_C_0:https://www.minicircuits.com/pdfs/LRPS-2-11.pdfBPF1:https://www.minicircuits.com/pdfs/LFCN-225D+.pdfA7:https://catalog.quanticxmw.com/Asset/CMA-84+.pdf