Mathcad - ee217projtodonew2.mcd

Gain Analysis
Z2Γ( Z)
Z
Z
G T
Γ G
, Γ L
, S
50 ohm
50 ohm
Available Power Gain
1 Γ L
2
2
S 2, 1
Power
2
. . 1 Γ G
1 S .
22 ,
Γ . L
1 S .
1, 1
Γ G S 12
Impedance to Reflection Coefficient Conversion
. . Γ L
Γ G
,
S 21 ,
.
2
Transducer Gain
G avail N, I C
, s 10. log G T Z2Γ Z S N, I C
, s , Z2Γ Z L N, I C
, s , Sparam N, I C
, s G avail N, I C
, s = 14.166 dB
15
25
Available Power Gain (dB)
14
13
Available Power Gain (dB)
20
15
12
0 5 10 15 20
10
0 20 40 60 80 100
Bias Current (mA)
Available Power Gain (dB)
Number of Devices in Parallel
Available Power Gain (dB)
Fig. 27: Power Gain vs. Bias Current
Fig. 28: Power Gain vs. Device Size
Distortion Analysis
The distortion analysis routines were copied directly from the thesis of Keng Fong [2]. They are
the most inaccurate portion of the design routine as they do not reflect the impact of the input
matching network on distortion performance. From comparisions to simulations we see the results
differ by 3-9dB. Future work will add the effects of the input matching network and bias circuitry.
Low distortion in a low noise amplifier is important to prevent undesired signals from
interfering with the desired signal. The most important measure of distortion performance is the
third order intercept point. The scenario where third order distortion is important is when the
receiving device is located a distance far from the transmitting device, and two devices are
transmitting signals close to the device, spacing at frequencies ∆f and 2*∆f from the desired
signal. Through third order distortion, the undesired signals, jammers, mix together to produce a
signal in the desired band. To prevent this signal from degradation the performance of the
receiver the low noise amplifier must be acceptably linear.
A measure of the third order intercept point is used define at acceptable level of linearity. The
third order intercept point is defined the as the jammer power required to make the amplitude of the
jammer equal to the power of the undesired signal produced through third order intermodulation.
This is shown graphically in the following figure.