Overview of modern load-pull and other non-linear measurement systems ARFTG Nonlinear Measurements Workshop San Diego, November 2001 Andrea Ferrero Dipartimento di Elettronica Politecnico di Torino, Italy

ARFTG –2001 – San Diego 2 Basics of load-pull zLoad-pull yControlling the loading condition at the output port zSource-pull yControlling the loading condition at the input port zFundamental load-pull yControlling the loading/source condition at the fundamental frequency zHarmonic load-pull yControlling the loading condition at one or more harmonic frequencies Definitions

ARFTG –2001 – San Diego 3 Basics of load-pull Example of load-pull data Output power 1dB gain compression Power Added Efficiency (PAE) 2dB gain compression

ARFTG –2001 – San Diego 4 Basics of load-pull zPower meter or scalar analyzer-based yonly scalar information on DUT performances yeconomic zVector receiver (ANA, 6-port) yvectorial and more complete informations on DUT performances yhigh accuracy, thanks to vector calibration yexpensive zTime Domain Receiver (MTA-NVNA) yWaveform capabilities yComplexity, high cost Measurement systems

ARFTG –2001 – San Diego 5 Passive load-pull systems zPassive loads yMechanical tuners yElectronic tuners (PIN diode-based) Power Meter Power Sensor Power Sensor and power sensors Passive tuners  S L

ARFTG –2001 – San Diego 6 Passive load-pull zFeatures ySingle or double slug tuners yHigh repeatability of tuner positions yPre-characterization with a network analyzer yHigh power handling

ARFTG –2001 – San Diego 7 Passive Load Pull Slab Line Motors DUT TUNERS

ARFTG –2001 – San Diego 8 Passive Limits zDrawback yLoad reflection coefficient limited in magnitude by tuner and test-set losses yThis is true especially for harmonic tuning xhigher frequency xoptimum load on the edge of the Smith chart

ARFTG –2001 – San Diego 9 PreMatching zPre-matching yTo reach higher gamma while characterizing highly mismatched transistors xPre-matching networks xPre-matched tuners  L LOSS  L  L zFeatures yHighest gamma attainable yDifficult pre-calibration (5D space!!) yHarmonic Loading uncontrolled

ARFTG –2001 – San Diego 10 PreMatching

ARFTG –2001 – San Diego 11 SWITCHING NETWORK PORT 2 Real Time load-pull Vector network analyzer-based system NETWORK ANALYZER DUT Input Load Output Load VECTOR INFO NORMAL VNA CAL ACTIVE LOADS

ARFTG –2001 – San Diego 12 Active load Active loop technique

ARFTG –2001 – San Diego 13 Harmonic Load Pull zControlling the Load/Source condition at harmonic frequencies zWaveshaping techniques at microwave frequencies zGreat complexity of the system but potential improvement of the performance

ARFTG –2001 – San Diego 14 Passive load-pull Passive Harmonic system zA Tuner for each harmonic yComplex yEasy to change frequency yMore control of the harmonic load zHarmonic Resonators yDifficult to change frequency yOnly Phase control of the load  f0  2f0 Fundamental Harmonic

ARFTG –2001 – San Diego 15 Harmonic active load-pull Extending the active loop technique Politecnico di Torino System

ARFTG –2001 – San Diego 16 Harmonic active load-pull Extending the active loop technique IRCOM Active Harmonic Load Pull

ARFTG –2001 – San Diego 17 4 Loops Harmonic system VNA Switching Unit Couplers Amplifier Loop Unit DUT and Probe Maury/Paf Active Harmonic Load Pull

ARFTG –2001 – San Diego 18 SWITCHING NETWORK Test Signal Time domain load-pull Transition Analyzer based system MTA TD WAVEFORMS DUT Input Load Output Load VECTOR AND TD INFO TD CAL REQUIRED ACTIVE LOADS Ref Signal

ARFTG –2001 – San Diego 19 Calibration and Verfication zPassive System yCoaxial VNA Measurement of the Tuners for different positions (typically thousands) yDe-embedding of external components (probe,cables..) zReal Time Active System yStandard Measurements directly at the reference plane yError Model as ordinary S-parameters

ARFTG –2001 – San Diego 20 Load-pull Accuracy zReference plane definitions VNA-based system: calibration   t Thru Line Short Load Open PwrMeter DUT 1  in 2  L 3 SWITCHING NETWORK NETWORK ANALYZER Probe Tip

ARFTG –2001 – San Diego 21 Main Contributions to Power Waves Calibration Residual Uncertainty zNWA measurement repeatability (0.1 %) zUncertainty on power calibration coefficient (input TWTA during calibration: 2%, no TWTA 0.5%) zOn-wafer probe position repeatability (0.2%) Uncertainty

ARFTG –2001 – San Diego 22 Passive LP System ztuner position repeatability zS-parameter measurement uncertainty: yresidual NWA calibration uncertainty yNWA repeatability zmeasured power uncertainty (power meter dynamic range) Main Contributions to Uncertainty

ARFTG –2001 – San Diego 23 Comparison Passive vs. Active Output Power Standard Uncertainty passive LP: red line active LP dBm

ARFTG –2001 – San Diego 24 zClassical PA design Information like: yPower Sweep yOptimum Loads zMAP based design zAdditional info with Active Real Time System yGammaIn yAM/PM conversion zHarmonic Load condition zTime Domain Info Load Pull and PA Design

ARFTG –2001 – San Diego 25 DATA SET EXAMPLE Load Pull and PA Design

ARFTG –2001 – San Diego 26 Power Sweep and more 1dB compression Point Pout=26.29dBm Gain= 9.72dB IM3R= dBc IM3L=-18.50dBc Eff=48.07 %

ARFTG –2001 – San Diego 27 Load Pull and PA Design OUTPUT 1 dB GAIN COMPRESSION POWER 1 dB GAIN COMPRESSION COMBINING LP MAP INFORMATION TO OPTIMIZE POWER PERFORMANCES 26dBm 12dB

ARFTG –2001 – San Diego 28 1 dB GAIN COMPRESSION C/I 3 POUT = 24 dBm COMBINING LP MAP INFORMATION TO OPTIMIZE LINEARITY PERFORMANCES 50% -28dBm Load Pull and PA Design

ARFTG –2001 – San Diego 29 Harmonic Information Harmonic Load Effect on Efficiency Power Added Efficiency (PAE) 4 GHz, 2dB gain compression as a function of the second harmonic load value (8 GHz).

ARFTG –2001 – San Diego 30 Time Domain LP Waveform check Istantaneous Working Point

ARFTG –2001 – San Diego 31 Conclusions zLoad-pull test set as important tools for: yPower amplifier design yModel Verification yDevice optimization zDifferent possibility available according to yTesting needs yApplication needs yBudget

ARFTG –2001 – San Diego 32 Many Thanks to yDave Hartskeerl - Philips Research Laboratories ySurinder Bali – Maury Microwave