Simulate LINC system in ADS
Song Lin @ECE.UTK
03/30/2005
What is the LINC?
There are many linearization techniques.
1.
Feed-forward
2.
Pre-distortion
3.
LINC
Linear amplification using nonlinear components
(LINC) is a technique whereby a linear modulation
signal is converted into two constant envelope signals
that are independently amplified by power-efficient
Class D amplifiers and then combined using a hybrid
coupler.
Fig1:Simplified block diagram for an outphasing power amplifier
The use of power efficient amplifiers can provide
significant improvement in the PAE of the overall
system.
Fig2:Separation of two component signals from the source signal
S1(t) and S2(t) are the modulated phase and
constant amplitude signals
The problem we want to solve
1.
2.
3.
4.
5.
6.
The
The
The
The
The
The
Class D Power amplifier.
reconfigurable Combiner.
phase detector.
phase shifter.
amplitude detector.
DSP part.
ADS simulation LINC at system level
ADS simulation results (ideal)
Time Domain Response
Frequency Spectrum after Transformation
8
10
10
6
0
0
-10
-20
-30
-40
Voutput, V
Vinput2_timedomain, V
Vinput1_timedomain, V
20
Power (dBm)
Power (dBm)
Frequency Spectrum at Input
20
-10
-20
-30
-40
-50
-50
-60
-60
-70
-70
2
0
-2
-4
-6
855
854
853
852
851
850
849
848
847
846
845
855
854
853
852
851
850
849
848
847
846
845
freq, MHz
4
freq, MHz
-8
0.0
0.1
0.2
0.3
0.4
0.5
0.6
time, usec
Frequency Spectrum at Output
40
10
30
0
20
10
-10
Power (dBm)
Power (dBm)
Frequency Spectrum after PA
20
-20
-30
-40
0
-10
-20
-30
-40
-50
-50
-60
-60
-70
845 846 847 848 849 850 851 852 853 854 855
freq, MHz
-70
845 846 847 848 849 850 851 852 853 854 855
freq, MHz
0.7
0.8
0.9
1.0
ADS simulation (non-ideal)
400
0.5
200
0.0
-200
-1.0
-400
100
200
300
400
200
0
-0.5
0
400
u11, mV
1.0
u22, mV
vout2, V
ADS simulation non-ideal results
500
-200
-400
0
time, nsec
100
200
300
400
0
500
100
time, nsec
400
200
300
400
500
400
500
time, nsec
300
400
200
100
0
-100
200
u21, mV
u12, mV
200
vout3, mV
0
0
-200
0
-200
-200
-400
-300
0
0
100
200
300
400
100
500
200
300
400
-400
500
0
time, nsec
time, nsec
1.0
200
0.0
vout3, mV
vout1, mV
vout, V
0.5
100
0
-100
0
300
time, nsec
400
500
0
-100
-300
-300
-1.0
100
-200
-200
-0.5
200
300
300
200
100
200
time, nsec
300
0
100
100
200
300
time, nsec
400
500
0
100
200
300
time, nsec
400
500
The class D power amplifier

Use the Load-Pull technology to match the output port

Use S parameter to match the input port
To simplify the design, I chose the narrow band system working
around 850MHz. To design the wideband PA, there is another way
to go for matching.
The phase detector

Use the MCU to control the comparing time,
and then get the relationship of the phase
different and the voltage. After getting the
voltage, we can use the MCU to control the
analogy phase shifter to balance the phase of
the two branches
Phase shifter
Wide band 90 degree lumped hybrid
Reconfigurable transformer
For the reconfigurable transformer, we still
have a long way to go. I think we can use
the switch to make the transmission line
transformer to be reconfigurable. Although
this kind of reconfigurable transformer can
get very high efficiency but it has very poor
isolation between the two input port. So
we should find the best point to meet the
requirement.
Several Technology to improve the LINC
ELINC
Next stage:


Combine the feedback technology and
the ELINC technology.
Figure out the reconfigurable power
combiner.
THANK YOU!