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Simulate LINC system in ADS Song Lin @ECE.UTK 03/30/2005
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.
The use of power efficient amplifiers can provide significant improvement in the PAE of the overall system.
Fig1:Simplified block diagram for an outphasing power amplifier
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. The Class D Power amplifier. 2. The reconfigurable Combiner.3. The phase detector.4. The phase shifter.5. The amplitude detector.6. The DSP part.
ADS simulation LINC at system level
Vinput1
Vinput2 VoutPA
Vout
Vinput
Output of LINC Transmitter
Transformation toConstant Envelopes
VARVAR1
Delta_Phase=0.001Delta_Gain=0.001rmax=1.414 VPavs_in=15 _dBmSpacing=2 MHzRFfreq=850 MHz
EqnVar
CouplerSingleCOUP5Coupling=10. dB
231
CouplerSingleCOUP2Coupling=10. dB
231
CouplerSingleCOUP4Coupling=10. dB
231
CouplerSingleCOUP1Coupling=10. dB
231
PwrSplit3PWR2S21=1.S31=1.S41=1.
I_ProbeIout
TermTerm2
Z=50 OhmNum=1
PwrSplit2PWR1
P_nTonePORT2
P[2]=polar(dbmtow(Pavs_in),0)P[1]=polar(dbmtow(Pavs_in),0)Freq[2]=RFfreq-Spacing/2Freq[1]=RFfreq+Spacing/2Z=50 OhmNum=2
PhaseShiftSMLPS3Phase=90.
PhaseShiftSMLPS1Phase=-90.
SDD5PSDD5P1Cport[1]=
TermTerm1
Z=50 OhmNum=1
TermTerm5
Z=50 OhmNum=1
AmplifierAMP1S21=dbpolar(0.0,0)
TermTerm3
Z=50 OhmNum=1
TermTerm6
Z=50 OhmNum=1
AmplifierAMP2S21=dbpolar(0.0+Delta_Gain,0+Delta_Phase)
HarmonicBalanceHB1
Order[2]=7Order[1]=7Freq[2]=RFfreq+Spacing/2Freq[1]=RFfreq-Spacing/2
HARMONIC BALANCE
ADS simulation results (ideal)
846847
848
849850
851852
853854
845
855
-60-50-40-30-20-10
010
-70
20
freq, MHz
Powe
r (dB
m)
Frequency Spectrum at Input
846847848849850851852853854
845
855
-60-50-40-30-20-10
010
-70
20
freq, MHz
Powe
r (dB
m)
Frequency Spectrum after Transformation
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.90.0 1.0
-6
-4-202
4
6
-8
8
time, usec
Vinp
ut1_
timed
omai
n, V
Vinp
ut2_
timed
omai
n, V
Vout
put,
V
T ime Domain Response
846 847 848 849 850 851 852 853 854845 855
-60-50-40-30-20-10
0102030
-70
40
freq, MHz
Powe
r (dB
m)
Frequency Spectrum at Output
846 847 848 849 850 851 852 853 854845 855
-60-50-40-30-20-10
010
-70
20
freq, MHz
Powe
r (dB
m)
Frequency Spectrum after PA
ADS simulation (non-ideal)
vout3
vout4
vout2
vout1
v41
v11
v31
v2
u21 u22u11
u21
vout
u11
classdpaX2
classdpaX3
TranTran1
MaxTimeStep=0.1 nsecStopTime=280 nsec
TRANSIENT
VARVAR1
f1=850 MHzf0=2 MHz
EqnVar
VARVAR2pav=16
EqnVar
HarmonicBalanceHB1
Order[2]=7Order[1]=7Freq[2]=f1Freq[1]=f0
HARMONIC BALANCE
P_1TonePORT4
Freq=f1P=polar(dbmtow(pav),120)Z=50 OhmNum=4
P_1TonePORT2
Freq=f0P=polar(dbmtow(pav),120)Z=50 OhmNum=2
P_1TonePORT5
Freq=f0P=polar(dbmtow(pav),0)Z=50 OhmNum=5
P_1TonePORT3
Freq=f1P=polar(dbmtow(pav),0)Z=50 OhmNum=3
PhaseShiftSMLPS1
ZRef=50. OhmPhase=180
TermTerm1
Z=50 OhmNum=1PwrSplit2
PWR3
S31=0.707S21=0.707
PwrSplit2PWR2
S31=0.707S21=0.707
PwrSplit2PWR1
S31=0.707S21=0.707
Mixer2MIX1
ConvGain=dbpolar(0,0)SideBand=LOWER
Mixer2MIX2
ConvGain=dbpolar(0,0)SideBand=LOWER
ADS simulation non-ideal results
100 200 300 4000 500
-0.5
0.0
0.5
-1.0
1.0
time, nsec
vout
, V
100 200 300 4000 500
-200
-100
0
100
200
-300
300
time, nsec
vout
1, m
V100 200 300 4000 500
-0.5
0.0
0.5
-1.0
1.0
time, nsec
vout
2, V
100 200 300 4000 500
-200
-100
0
100
200
-300
300
time, nsec
vout
3, m
V
100 200 300 4000 500
-200
0
200
-400
400
time, nsecu2
2, m
V
100 200 300 4000 500
-200
0
200
-400
400
time, nsec
u12,
mV
100 200 300 4000 500
-200
0
200
-400
400
time, nsec
u11,
mV
100 200 300 4000 500
-200
0
200
-400
400
time, nsec
u21,
mV
100 200 300 4000 500
-200-100
0100200
-300
300
time, nsec
vout
3, m
V
The class D power amplifier Use the Load-Pull technology to match the output
port
vload
Vs_low Vs_high
Refer to the example design file: examples/RF_Board/LoadPull_prj/HB1Tone_LoadPull_eqns for details about how this simulation is run. Refer to the data display file"ReflectionCoefUtility" in the sameexample project for help in setting s11_rho and s11_center.
s11_rho is the radius and s11_center is thecenter of the circle.(But this is just a static drawing.)
One Tone Load Pull Simulation; output power and PAE found at each fundamental load impedance
Set Load and Source impedances atharmonic frequencies
Set these values:
Specify desired Fundamental Load Tuner coverage: s11_rho is the radius of the circle of reflection coefficients generated. However, the radius of the circle will be reduced if it would otherwise go outside the Smith Chart.s11_center is the center of the circle of generated reflection coefficientspts is the total number of reflection coefficients generatedZ0 is the system reference impedance
VARSTIMULUS
Vlow=-2.7Vhigh=4.8RFfreq=850 MHzPavs=23 _dBm
EqnVar
P_1TonePORT1
Freq=RFfreqP=dbmtow(Pavs)Z=50 OhmNum=1
VARVAR3Z_s_fund=10
EqnVar
S1P_EqnS1S[1,1]=LoadTunerZ[1]=Z0
VARVAR2
Z_s_5 =10* Z0 + j*0Z_s_4 =10* Z0 + j*0Z_s_3 =10* Z0 + j*0Z_s_2 =10* Z0 + j*0Z_l_5 =10* Z0 + j*0Z_l_4 =10* Z0 + j*0Z_l_3 =10*Z0 + j*0Z_l_2 =10*Z0 + j*0
EqnVar
ParamSweepSweep1
PARAMETER SWEEP
ClassDampX2
OutBiasInBiasOutputInput
VARImpedanceEquationsEqn
Var
HarmonicBalanceHB1
Order[1]=9Freq[1]=RFfreq
HARMONIC BALANCE
I_ProbeIload
VARSweepEquations
Z0=50pts=100s11_center =-0.65 +j*0.0s11_rho =0.35
EqnVar
V_DCSRC1Vdc=Vhigh
V_DCSRC2Vdc=Vlow
LL2
R=L=1 uH
LL1
R=L=1 uH
I_ProbeIs_low I_Probe
Is_high
Statz_ModelFLC301XP
Imelt=Trise=
Use S parameter to match the input port
DA_LEMatch1_matchadDA_LEMatch1
Zload=0.534-j*14.216Zin=50 OhmF=850 MHz
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
vout
v2v22
v12
v11v21
v1u1
u2RR13R=50 Ohm
VARVAR1
Delay_Time=1/Fref secStop_Time=200 usecStep_Time=1/(10*Fref) secKv = 3.37 MHzLogic0=0.5Logic1=4.5Fref =250 kHzN_Step =10N0 = 161
EqnVar
VARVAR2phase2=45
EqnVar
VARVAR5
n=2phase1=180
EqnVar
TranTran2
MaxTimeStep=1 usecStopTime=20 usec
TRANSIENT
PhaseShiftSMLPS1
ZRef=50. OhmPhase=phase2
VSumSUM1
VtSineSRC4
Phase=0Damping=0Delay=0 nsecFreq=0.25 MHzAmplitude=1 VVdc=0 V
VtSineSRC2
Phase=phase1Damping=0Delay=n*4 usecFreq=0.25 MHzAmplitude=1 VVdc=0 V
VtSineSRC3
Phase=phase1Damping=0Delay=n*4 usecFreq=0.25 MHzAmplitude=1 VVdc=0 V
VtSineSRC1
Phase=0Damping=0Delay=0 nsecFreq=0.25 MHzAmplitude=1 VVdc=0 V
VSumSUM2
VARVAR4
Clpf1=6.86 nFRlpf2=1.856 KohmRlpf1=2.935 Kohm
EqnVar
RR12R=Rlpf1
CC4C=Clpf1
CC5C=Clpf1
RR10R=Rlpf2
RR11R=Rlpf2
OpAmpIdealAMP2
RRR4R=Rlpf1
ResetSwitchSWITCH1
t>0t=0
ResetSwitchSWITCH3
t>0
t=0
PhaseFreqDet2PFD2
J itter=0 psecDeadTime=0 psecVlow=Logic0Vhigh=Logic1
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
VARVAR1
Ccap=750 pFL1=0.4 nHR2=3200 OhmCc=1 pFR1=3200 Ohm
EqnVar
S_ParamSP1
Step=Stop=1 GHzStart=0.5 GHz
S-PARAMETERS
Hybrid90HY B1
PhaseBal=0GainBal=0 dBLoss=0.1 dB
-900
IN ISO
S_ParamSP2
Step=Stop=0.1 GHzStart=0.03 GHz
S-PARAMETERS
CC3C=Cc
CC4C=Cc
RR5R=R1 Ohm
RR4R=R1 Ohm
V_DCSRC1Vdc=2 V
di_sms_bb833_19930908D4
di_sms_bb833_19930908D2
di_sms_bb833_19930908D1
di_sms_bb833_19930908D3
TermTerm1
Z=50 OhmNum=1
CC1C=Ccap
TermTerm2
Z=50 OhmNum=2
CC2C=Ccap
LL3
R=L=L1
LL2
R=L=L1
Wide band 90 degree lumped hybrid S_ParamSP1
Step=Stop=1 GHzStart=0.7 GHz
S-PARAMETERS
VARVAR1
C4=4.67 pFC3=4.97 pFC1=4.45 pFL5=14.04 nHL2=6.37 nHL1=6.617 nH
EqnVar
CC4C=C3
CC2C=C4
CC6C=C1
CC1C=C1
CC5C=C4
CC3C=C3
LL6
R=L=L5
LL5
R=L=L5
LL4
R=L=L1
LL3
R=L=L2
LL2
R=L=L2
LL1
R=L=L1
TermTerm1
Z=50 OhmNum=1
TermTerm2
Z=50 OhmNum=2
TermTerm3
Z=50 OhmNum=3
TermTerm4
Z=50 OhmNum=4
Reconfigurable transformer
vmid
vin2
vin1vout
RR2R=5 Ohm VAR
VAR1
R1=100 Ohmn2=0.1n1=0.5
EqnVar
P_1TonePORT2
Freq=1 GHzP=polar(0.002,0)Z=50 OhmNum=2
TranTran1
MaxTimeStep=0.01 nsecStopTime=2.0 nsec
TRANSIENT
P_1TonePORT1
Freq=1 GHzP=polar(0.001,0)Z=50 OhmNum=1
TFTF3T=n2
TFTF1T=0.5
PhaseShiftSMLPS1
ZRef=50. OhmPhase=180.
I_ProbeI_Probe3
TFTF2T=n1
I_ProbeI_Probe2
RR1R=R1
I_ProbeI_Probe1
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!
