Optimizing Superheterodyne Receiver Design: LNA, Mixer, and IF Calculations

  • Thread starter Mickydawg25
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In summary, it is necessary to gather all the necessary information, double check units and assumptions, and consider all sources of noise in order to accurately calculate the overall noise figure and gain of the super heterodyne receiver.
  • #1
Mickydawg25
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Homework Statement


super heterodyne receiver made up of a LNA a mixer and an IF respectively.

LNA
NF1=?
G1=?

MIXER
NF2=2.5DB
G2=-3.5DB

IF AMPLIFIER
NF3=28DB
G3=7DB

THE OVERALL NF OF THE RECEIVER SHUD NOT EXCEED 6.5DB AND THE OVERALL GAIN SHOULD NOT EXCEED 32DB


Homework Equations



FRIIS EQUATION

NR=NR1 + NR2-1/G1 + NR3-1/G1.G2

The Attempt at a Solution



NR2=2.24
G2=0.446
NR3=5.011
G3=630.96

GTOT=32=G1+28-3.5=7.5DB
G1=5.62

NF OF SYSTEM =6.5DB=4.467

USING FRIIS
2.647=NR1
therefore NF1=4.23dB

Am I working out the gain and the NF of the LNA correctly? or is there other bits of info I should need/be using
 
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  • #2
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I would first clarify any missing information or assumptions made in the post. For example, the frequency range of the receiver, the input power level, and any specifications for the components (e.g. noise figure and gain of LNA). I would also confirm the units for the parameters mentioned (e.g. is G in dB or linear?). Once all the necessary information is gathered, I would proceed with the calculations.

Based on the information given, it seems like the calculations for the overall gain and noise figure of the system are correct. However, it is important to double check the units and ensure that they are consistent throughout the calculations.

Additionally, I would suggest considering the noise figure and gain of the LNA in the Friis equation, as it may have an impact on the overall noise figure and gain of the system. I would also check if there are any other sources of noise in the system that need to be taken into account.

Overall, it is important to carefully analyze and verify all the calculations and assumptions made in order to ensure accurate results.
 

FAQ: Optimizing Superheterodyne Receiver Design: LNA, Mixer, and IF Calculations

What is a superheterodyne receiver?

A superheterodyne receiver is a type of radio receiver that uses a process called heterodyning to convert incoming radio signals to a fixed intermediate frequency (IF) before being amplified and demodulated. This allows for better selectivity and sensitivity compared to other types of receivers.

How does a superheterodyne receiver work?

A superheterodyne receiver works by using a local oscillator to mix the incoming radio frequency with a fixed frequency to produce an intermediate frequency. This intermediate frequency is then amplified and demodulated to extract the original audio signal.

What are the advantages of using a superheterodyne receiver?

Superheterodyne receivers offer several advantages, including better selectivity, sensitivity, and stability. They also allow for the use of a single IF stage, making the receiver more compact and less complex compared to other types of receivers.

What are the components of a superheterodyne receiver?

The main components of a superheterodyne receiver include an antenna, a mixer, a local oscillator, an intermediate frequency amplifier, a demodulator, and an audio amplifier. Additional components may also be included, such as filters and automatic gain control circuits.

What is the difference between a superheterodyne receiver and other types of receivers?

The main difference between a superheterodyne receiver and other types of receivers is the use of heterodyning to convert the incoming radio frequency to an intermediate frequency. This allows for better performance and selectivity compared to direct-conversion or TRF (tuned radio frequency) receivers.

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