LARGE-SIGNAL NETWORK ANALYZER MEASUREMENTS AND THEIR USE IN DEVICE MODELLING

Ewout Vandamme (Agilent Technologies, NMDG), Wladek Grabinski (Motorola, Geneva), Dominique Schreurs (K.U.Leuven), and Thomas Gneiting (ADMOS) LARGE-SIGNAL NETWORK ANALYZER MEASUREMENTS AND THEIR USE IN DEVICE MODELLING

Outline Large-Signal Network Analyzer (LSNA) technology Advantages of using LSNA for device modelling engineers LSNA measurements de-embedding implementation in CAE tool (iccap) measurement and simulation results tuning of model parameter to LSNA measurements Conclusions 2

Agilent s Large-Signal Network Analyzer technology RF bandwidth: 600 MHz - 20 GHz max RF power: 10 Watt IF bandwidth: 8 MHz Needs CW or periodic modulation (a) Calibration Standards: a 1 a 2 Cal Kit, b 1 b 2 e.g. LOS, LRRM, etc. or, equivalently, Power Std i 1 i 2 v 2 Phase Std v 1 3

CW class of signals measured with LSNA 2-port Device-Under-Test (DUT) under periodic excitation e.g. transistor excited by a 2.4 GHz tone with an arbitrary output termination All current and voltage waveforms are represented by a fundamental and harmonics DC 1*f 0 2*f 0 3*f 0 4*f 0 Freq. (f 0 =2.4 GHz) Spectral components X h = complex Fourier Series coefficients of the waveforms 4

LSNA measurements: time domain, frequency domain or combination of both (e.g. envelope in modulation) H 1 t = j h f t X e f 2π ( ) Re j 2π h Xh = 2 f x( t) e h= x 0 f = 1/ period= fundamenta l frequency 0 h f t dt 5

Advantages of using the LSNA in device modelling Measure the following characteristics of your DUT making a single connection, using one measurement setup (the LSNA) DC, Small-signal (Scattering parameters), and Large-signal behaviour Verify the model accuracy of your device under realistic operation conditions power amplification high-speed switching Identify modelling problems at a single glance LSNA measurements, e.g., immediately reveal weaknesses in capacitance and charge models 6

Use of LSNA measurements in CAE tool (iccap) model verification, optimisation (and extraction) sweep of Power Vgs Vds Freq ICCAP specific input ADS netlist. Used, a.o., to impose the measured impedance to the output of the transistor in simulation 7

Use of LSNA measurements for simulation (1/2) Measurements RF de-embedding Reference planes before and after de-embedding a 1c b 1c a 2c b 2c v 1c i 1c v 2c i 2c @ f 0, 2*f 0, V 1m,dc V 2m,dc calibrated I 1m,dc I 2m,dc LSNA accounts for cable resistances V 1,dc I 1,dc V 2,dc I 2,dc v 1c i 1c v 1d i v 2c i 1d 2c v2d i 2d 8

De-embedding intermezzo (1/2) Equivalent circuit of the RF test-structure, including the DUT and layout parasitics Gate current / ma 2 before after 1 0-1 - 2 de-embedding - 3 0 0.5 1 1.5 2 Time/period 9

De-embedding intermezzo (2/2) Detailed view on the layout of the RF MOSFET for minimum influence of pad parasitics 10

Use of LSNA measurements for simulation (2/2) RF de-embedding Reference planes before and after de-embedding Simulations Compare measurements: v 1d v 2d i 1d i 2d v 1c i 1c v 1d i v 2c i 1d 2c v2d i 2d with simulations: v 1s v 2s i 1s i 2s R de1 and R de2 are de-embedding resistances (in dc path) The load impedance Z L at f=n*f 0 equals 50 Ω if a 2n <-50 dbm 11

Input capacitance behaviour V ds,dc =0.3 V V gs,dc =0.9 V V ds,dc =1.8 V Input loci turn clockwise, conform i=c*dv/dt 12

Dynamic loadline & transfer characteristic V ds,dc =0.9 V V gs,dc =0.3 V 13

Dynamic loadline & transfer characteristic V ds,dc =0.9 V V gs,dc =0.9 V DC operating point if RF not present self-biasing 14

Dynamic loadline & transfer characteristic V ds,dc =0.9 V V gs,dc =1.8 V Cable resistance + R de2 loss 15

Intermezzo (1/2): extrapolation example SiGe HBT Model parameters extracted using DC measurements up to 1 V 1.2 1.7 1.1 1.0 1.6 v1mts_de v1sts 0.9 0.8 v2mts_de v2sts 1.5 1.4 0.7 0.6 1.3 0.5 0.002 0.001 0 100 200 300 400 500 600 700 800 900 time, psec 1.2 0.008 0.006 0 100 200 300 400 500 600 700 800 900 time, psec meas. simul. i1mts_de i1sts 0.000-0.001 i2mts_de i2sts 0.004 0.002-0.002 0.000-0.003 0 100 200 300 400 500 600 700 800 900 time, psec -0.002 0 100 200 300 400 500 600 700 800 900 time, psec SiGe HBT V be = 0.9 V; V ce =1.5 V; P in = - 6 dbm; f 0 = 2.4 GHz 16

Intermezzo (2/2): extrapolation example SiGe HBT Measured and simulated DC characteristics SiGe HBT - DC characteristics DCmeas1..Ice 0.025 0.020 0.015 0.010 0.005 0.000-0.005-0.010-0.015 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 VbDC Measurement i2.i 0.025 0.020 0.015 0.010 0.005 0.000-0.005-0.010-0.015 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 VbDC Simulation Alcatel Microelectronics and the Alcatel SEL Stuttgart Research Center teams are acknowledged for providing these data. 17

AM to AM (gain) and AM to PM versus input power 1 db compressi on V ds,dc =V gs,dc =1.2 V 18

Drain current & gate voltage time domain waveforms Class C Class AB Class A v in v in v in V gs,dc =0.3 V V ds,dc =0.9 V V gs,dc =0.9 V V gs,dc =1.2 V 19

Effect of operating regime on dissipated power in the DUT, load, and DC power supply class AB Instantaneous power dissipated in DUT Power delivered by DC supply RFoutput power at f=f 0 PAE=37 % V ds,dc =0.9 V, V gs,dc =0.9 V 20

Effect of operating regime on dissipated power in the DUT, load, and DC power supply class A Instantaneous power dissipated in DUT Power delivered by DC supply RF output power at f=f 0 PAE=11 % V ds,dc =0.9 V, V gs,dc =1.8 V 21

Tuning of model parameters to LSNA measurements before after 22

LSNA measurements in device modelling Conclusions: Unique tool for complete large-signal model accuracy assessment under realistic RF or microwave signals information on amplitude and phase Reduce number of design cycles and reduce manufacturing costs through better device models, thus more optimal designs Optimize model parameters to LSNA measurements Benchmark various device models, e.g., BSIM, MM11, EKV, Gummel-Poon, VBIC, MEXTRAM, HICUM,... Build confidence in your model 23

Contact For info on LSNA technology, visit http://www.agilent.com/find/lsna Soon, a measurement and consulting service related to Large-Signal Network Analyzer Technology will be available through the NMDG group in Belgium. For info, you need to contact NMDG directly at email: Marcus_Vandenbossche@agilent.com, or tel.: +32-3 - 890 46 16 24