Low Noise Amplifier (LNA)

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Low Noise Amplifier (LNA)

• Presented By
• Mohammad Jameel

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Mathmatical / Behavorial Model of LNA
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Designed Mathmatical Model of LNA , Contd
Characterization of Non-Linearity (AM/AM)

• Non-linearity of LNA may be characterized by
  following equation.
• Let x(t) is input to a nonlinear pass band model.
  Output y (t) of this system is given by
• y(t) a1x(t) a2x2(t) a3x3(t) a4x4(t)
  a5x4(t)
• Baseband equivalent of y(t) is given as follows.
• ybb(t) (a1 a3x(t) 2 a5x(t) 4)x (t) -
  - - eq. 1
• Input Signal magnitude and these three
  coefficients (a3,a5 ,a1) are combined according
  to the above equation to obtain the AM/AM output
  as even order harmonics( a2, a4, a6 ) do not
  produce Inter-Modulation (IM) products therefore
  they are not taken into account in calculation.
• Intermodulation is one of the major causes of
  distortion in RF systems.

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Characterization of Non-Linearity (AM/AM)

• In order to quantify intermodulation third
  intercept point (IP3) has been devised.
• Definition of IP3
• The point where the linear gain (a2A2) and 3rd
  order non-linearity (20log(3a3A3/4) )intercept
  with the increase in level of input signal (A) is
  called 3rd order intercept point (IP3). It is a
  given value and is used to calculate a3 and P1dB
  ( 1 dB compression point)

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Characterization of Non-Linearity (AM/AM)

• AM/AM Simulink Block
• Where u magnitude of input signal
• LGAIN/ a1 input linear gain
• IP3 3rd Intercept Point
• u / Out1 modulated magnitude
  of input signal

AM/AM
u
LGAIN
u / Out 1
IP3
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Characterization of Non-Linearity (AM/AM)

• a3/ k3 Simulink Block
• Where
• LGAIN/ a1 input linear gain ( 1
  - 1000 )
• IP3 3rd Intercept Point ( Range
  5 100 dbm )
• a3 3rd order coefficient/ 3rd
  order gain
• V1 dB/ P1 dB 1 dB Gain
  compression point

a3/ k3
LGAIN
a3
IP3
V1 dB/ P1 dB
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Characterization of Non-Linearity (AM/AM)

• a3/ k3 Simulink Block

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Characterization of Non-Linearity (AM/AM)

• a5/ k5 Simulink Block

Where a3 3rd order coefficient/
3rd order gain LGAIN/a1 input
linear gain V1 dB/ P1 dB 1 dB
Gain compression point a5 5th
order coefficient/ 5th order gain
a5/ k5
a3
LGAIN
a5
V1 dB/ P1 dB
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Characterization of Non-Linearity (AM/AM)

• a5/ k5 Simulink Block

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AM / AM Simulation in MATLAB

• The figures below shows the simulation result
  ip3 10dbm ip3 80 dbm

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AM / AM Simulation in Verilog

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AM / AM Simulation in Verilog

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Addition of Thermal Noise

• Addition of thermal noise
• AWGN noise is added to the output of AM/AM block.
  This block calculates white noise for the input
  signal
• Pn 4kRTfs
  (10NF/101)
• Where NF Noise Factor 2, R System Impedance
  1, K Boltzmann Constant
• fs Sample rate 0, T Temperature 290 K
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Inherent Characteristics of LFSR

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Desired Characteristics of LFSR