LARGE-SIGNAL NETWORK ANALYZER … NETWORK ANALYZER MEASUREMENTS AND THEIR USE IN ... • tuning of model parameter to LSNA measurements ... extrapolation example SiGe HBT

Ewout Vandamme (Agilent Technologies, NMDG),Wladek Grabinski (Motorola, Geneva),Dominique Schreurs (K.U.Leuven), andThomas Gneiting (ADMOS)

LARGE-SIGNAL NETWORK ANALYZER MEASUREMENTS AND THEIR USE IN

DEVICE MODELLING

Mixdes 2002© 2002, Agilent Technologies

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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


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Agilent’s Large-Signal Network Analyzer technology

Cal Kit,e.g. LOS, LRRM, etc.

Power Std

Phase Std

Calibration Standards: a1b1

a2b2

i1v1

or, equivalently,i2

v2

(a)

• RF bandwidth: 600 MHz - 20 GHz• max RF power: 10 Watt• IF bandwidth: 8 MHz• Needs CW or periodic modulation


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• 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

• Spectral components Xh = complex Fourier Series coefficients of the waveforms

CW class of signals measured with LSNA

Freq. (f0=2.4 GHz)1*f0 2*f0 3*f0 4*f0DC


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LSNA measurements: time domain, frequency domain or combination of both (e.g. envelope in modulation)

= ∑=

H

h

tfhjh eXtx

0

2Re)( π

∫−

−=1

0

2)(2f

tfhjh dtetxfX π

frequencylfundamentaperiodf == /1


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Advantages of using the LSNA in device modelling

• Measure the following characteristics of your DUT making a singleconnection, 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


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Use of LSNA measurements in CAE tool (iccap)⇒⇒⇒⇒ model verification, optimisation (and extraction)

ICCAP specific input

ADS netlist. Used, a.o., to impose themeasured impedance to the output ofthe transistor in simulation

sweep of Power Vgs Vds Freq


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Use of LSNA measurements for simulation (1/2)

Measurements RF de-embedding

V1m,dc I1m,dcV2m,dc I2m,dc

a1c b1ca2c b2c

v1c i1cv2c i2c

calibrated

V1,dc I1,dcV2,dc I2,dc

⇒LSNA accounts forcable resistances

v1c i1cv2c i2c

v1d i1dv2d i2d

⇒

⇒

@ f0, 2*f0, …

Reference planes beforeand after de-embedding

⇔


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De-embedding intermezzo (1/2)

0 0.5 1 1.5 2

- 3

- 2

- 1

0

1

2 beforeafter

de-embedding

Time/period

Gate

curre

nt / m

A

Equivalent circuit of the RF test-structure, including the DUT and layout parasitics


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De-embedding intermezzo (2/2)

Detailed view on the layout of the RF MOSFET

for minimum influence of pad parasitics


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Use of LSNA measurements for simulation (2/2)

RF de-embedding Simulations

v1c i1cv2c i2c

v1d i1dv2d i2d

⇒

v1d i1dv2d i2d

Comparemeasurements:

with simulations:v1s i1sv2s i2s

⇒

Rde1 and Rde2 are de-embedding resistances (in dc path)The load impedance ZL at f=n*f0 equals 50 Ω if a2n<-50 dBm

Reference planes beforeand after de-embedding


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Input capacitance behaviourVgs,dc=0.9 VVds,dc=0.3 V Vds,dc=1.8 V

Input loci turn clockwise, conform i=C*dv/dt


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Dynamic loadline & transfer characteristicVgs,dc=0.3 VVds,dc=0.9 V


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Dynamic loadline & transfer characteristicVds,dc=0.9 V Vgs,dc=0.9 V

DC operating point if RFnot present ⇒⇒⇒⇒ self-biasing


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Dynamic loadline & transfer characteristicVgs,dc=1.8 V

Cable resistance + Rde2 loss

Vds,dc=0.9 V


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Intermezzo (1/2): extrapolation example SiGe HBTModel parameters extracted using DC measurements up to 1 V

100 200 300 400 500 600 700 8000 900

-0.002

-0.001

0.000

0.001

-0.003

0.002

time, psec

i1sts

i1mts_de

100 200 300 400 500 600 700 8000 900

0.6

0.7

0.8

0.9

1.0

1.1

0.5

1.2

time, psec

v1sts

v1mts_de

100 200 300 400 500 600 700 8000 900

1.3

1.4

1.5

1.6

1.2

1.7

time, psec

v2sts

v2mts_de

100 200 300 400 500 600 700 8000 900

0.000

0.002

0.004

0.006

-0.002

0.008

time, psec

i2sts

i2mts_de

SiGe HBT Vbe= 0.9 V; Vce=1.5 V; Pin= - 6 dBm; f0= 2.4 GHz

simul.meas.


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Intermezzo (2/2): extrapolation example SiGe HBTMeasured and simulated DC characteristics

Measurement Simulation

SiGe HBT - DC characteristics

0.2 0.4 0.6 0.8 1.0 1.2 1.40.0 1.6

-0.010

-0.005

0.000

0.005

0.010

0.015

0.020

-0.015

0.025

VbDC

DCmeas1..Ice

0.2 0.4 0.6 0.8 1.0 1.2 1.40.0 1.6

-0.010

-0.005

0.000

0.005

0.010

0.015

0.020

-0.015

0.025

VbDC

i2.i

Alcatel Microelectronics and the Alcatel SELStuttgart Research Center teams are acknowledged

for providing these data.


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AM to AM (gain) and AM to PM versus input power

Vds,dc=Vgs,dc=1.2 V

1 dBcompression


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Drain current & gate voltage time domain waveforms

Vgs,dc=0.3 V

“Class C” Class AClass AB

Vgs,dc=1.2 VVgs,dc=0.9 VVds,dc=0.9 V

vinvin

vin


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Effect of operating regime on dissipated power in the DUT, load, and DC power supply — class AB

Vds,dc=0.9 V, Vgs,dc=0.9 V

RFoutput powerat f=f0

Instantaneouspower dissipatedin DUT

Powerdelivered byDC supply

PAE=37 %


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Effect of operating regime on dissipated power in the DUT, load, and DC power supply — “class A”

Vds,dc=0.9 V, Vgs,dc=1.8 V

RF output powerat f=f0

Instantaneouspower dissipatedin DUT

Powerdelivered byDC supply

PAE=11 %


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Tuning of model parameters to LSNA measurements

before

after


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LSNA measurements in device modellingConclusions:• 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


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Contact

• For info on LSNA technology, visithttp://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 atemail: [email protected], ortel.: +32 - 3 - 890 46 16

LARGE-SIGNAL NETWORK ANALYZER … NETWORK ANALYZER MEASUREMENTS AND THEIR USE IN ... • tuning of model parameter to LSNA measurements ... extrapolation example SiGe HBT

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LARGE-SIGNAL NETWORK ANALYZER … NETWORK ANALYZER MEASUREMENTS AND THEIR USE IN ... • tuning of model parameter to LSNA measurements ... extrapolation example SiGe HBT