1. Amplifiers Amplifier Parameters Gain = Po/Pi in dB = 10 log (Po/Pi)
Gain Flatness (Gian Ripple vs. frequency) “the maximum deviation of the gain over specified frequency range”
Gain Variation vs. Temperature
1 dB Output Compression point
Noise Figure
Efficiency
Bandwidth
Limited Power Output
Third Order Output Intercept Point
Second Order Output Intercept Point
VSWR (Voltage Standing Wave Ratio), Return Loss
Reverse Isolation (output to input)

2. Amplifier Gain Flatness

3. Amplifier Gain Variation vs. Temperature

4. 1 dB Output Compression Point
The 1dB Compression output point is used to specify the power output capability of an amplifier    30 20 10
-10
Power Gain:
Gain = Pout/Pin
Gain (dB) =
Pout - Pin (dBm)
Gain changes with output power level.
1 dB compression point
Saturation gain
Pout (dBm)
Linear gain
Pin (dBm)

5. Amplifier Noise Figure (NF) or F
An ideal amplifier adds no noise to the signal being amplified. However, all practical amplifiers generate noise.
(S/N)i
(S/N)o
F = No
GNi =
The Noise Figure of the amplifier in most cases determines the sensitivity of the receiver.
Efficiency:  = Pout/(Pdc in + Pin) Power added efficiency
Bandwidth: BW = (fH-fL)/fM
fM = (fH-fL)/2

6. Intercept Points
Intercept Points are located in the non-lnear portion (amplifier in saturation) of
the Pi vs. Po curve
Intermodulation occurs when two or more signals are present simultaneously.
In the non-linear region, the relationship between the input and output of an
amplifier can be written as
Vo = a1Vi + a2Vi2 + a3Vi
where Vo and Vi are the output and input voltage of the amplifier; a1, a2, etc. are the coefficients
The second order term( a2Vi2 creates second order intermodulation
The third order intercept point (a3Vi3 creates third order intermodulation

7. Intercept Points Cont.

8. Harmonic and spurious response:
Fundamental
2nd Harmonic
~ 10 dB below fund. at sat
3rd Harmonic
Spurious 10 dB below fund
White noise
Frequency
Power
Ripple components
in RF out
(-60dBc)
Intermodulation product:

9. Types of Microwave Semiconductor Amplifiers
Power Amplifiers
LNA

10. (1) Select transistor [S-and Noise parameters)
LNA Design
(1) Select transistor [S-and Noise parameters)
(2) Stability analysis
(3) Find appropriate load and source impedance
(4) Design matching and biasing networks
(5) Check out-of-band stability (suitable simulator is recommended)
(6) Realization
(7) Measurements
(8) Adjustment and correction

13. Power Amplifier Design
(1) Select transistor (Frequency – Power- non-linear parameters)
(2) Choose class of operation (A, AB, B, C, D,….) and then appropriate bias condition
(2) Non-linear characterization
(3) Find appropriate load and source impedances
(4) Design matching and biasing networks
(5) Check out-of-band stability (suitable simulator is recommended)
(6) Realization
(7) Measurements
(8) Adjustment and correction

14. Le gain à 1.64 GHz est de dB 25
-25 25
-25
S21
S11 (dB)
1,4
1,8
Freq. GHz

15. Single GaAs FET Amplifier
Gain per stage 5-6 dB PA to dB LNA
Output 1dB Compression Point
LNA < + 10 dBm
Med PA +18 dBm to 21 dBm
Output Third Order Intercept Point
Typically 8-10 dB above the 1 dB Compression Point
Output Second Order Intercept Point
Typically 8-10 dB above the output third order intercept point
Saturation Level
Typically 3-6 dB above the 1dB compression point
3 dB for medium to high power amplifier
5-6 dB for low noise amplifier

16. Amplifier Temperature Effect and Compensation
For a single stage amplifier
Typical amplifier gain changes are plus and minus 1dB from room temperature (~ dB/oC per stage)
Gain decreases 1dB per stage for ( +25oC to 95oC)
Gain increases 1dB per stage for ( +25oC to -45oC)
Amplifier gain compensation is usually inserted either between amplifier stages or within various points in the receiver chain
Temperature compensation options inculde:
PIN diode attenuators driven by a thermistor
MMIC attenuators
Variable gain amplifier

17. Balanced Amplifier S11 = S22 = 0 BW 4:1 Ideal for cascading compact
If one stage opens, Pout drop 6dB