In-Circuit Probing Presentation
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Transcript of In-Circuit Probing Presentation
HIP @ ICE
using high-impedance probesfor in-circuit voltage
time-domain measurements
2/2012
© NMDG
© NMDG 2012 2
Summary
Goal: accurate in-circuit measurement of time-domain voltage using one or more high-impedance probes (HIP) within a large-signal network analysis context @ locations normally unreachable using a vector network analyzer
Supported: Multiple probes Probing on PCB Probing on wafer
What are the voltage waveforms in-between the components?
How to measure these accurately? Apply proper calibration techniquesHow to minimize their disturbance? Use high-impedance probes
© NMDG 2012 3
Outline
Calibrated measurement using “home-made” HIP and ZVxPlus (*)
Measurement setup Measurement results Impact of high-impedance probing Calibration
Calibrated measurement using commercial Kelvin probe and real-time scope Measurement setup Measurement results Impact of high-impedance probing Calibration
(*) R&S ZVA24 VNA with nonlinear extensions to allow time-domain measurements
© NMDG 2012 4
Measurement using calibrated HIP in practice (I)Sanity check measuring the output voltage of an E-pHEMT FET
-5 dBm input @ 250 MHz, Vgs = 0.4 V, Vds = 4 V
2nd calibrated HIP probe allows to measure the input voltage
2nd
probeprobe
source 50Ωtermination
P1 P2P4synchronizer P3
probes
© NMDG 2012 5
Measurement using calibrated HIP in practice (II)
v2(t)excellent agreement between output voltage (red)measured using the TRL-calibrated coupler-basedtwo-port network analyzer and the voltage (green)measured by the calibrated high-impedance probe
v2(f)corresponding excellent agreement
of amplitude and phase in thefrequency domain
upper: coupler-based amp & phaselower: calibrated HIP amp & phase
© NMDG 2012 6
Measurement using calibrated HIP in practice (III)“a global ICE perspective”
© NMDG 2012 7
Impact of high-impedance probing(*)
The impedance of the probe is measured during calibration↓
The impact of the high-impedance probe can be taken into account
Estimated impedance of “home-made” (2k4) HIP
0.5 1 1.5 2
1400
1600
1800
2000
2200
2400
2600 0.5 1 1.5 2
60
50
40
30
20
10
f (GHz)
f (GHz)| ZHIP |
ZHIP (deg)
(*) in fact the combination of the probe, cable and receiver input
© NMDG 2012 8
Including impact of high-impedance probe during simulation
Probe
including the load effect of the probe in the simulation to compare measurements with simulations
v1i1
i2v2v probe
Figure and schematic courtesy of AWR
© NMDG 2012 9
Calibration process
Step 1: perform a “standard” one-port or two-port VNA calibration, extended with power and phase calibration to measure time-domain information
Step 2: use the calibrated system resulting from step 1 to calibrate the high-impedance probe
Step 3: use the calibrated high-impedance probe to measure the time-domain voltage in-circuit
© NMDG 2012 10
Calibration of high-impedance probe (step 2)
Different options are possible, such as :
Starting from an absolute TRL-based two-port calibration : Connect the HIP to the open of the TRL calibration kit (fig. 1) Connect the HIP to the thru of the TRL calibration kit (fig. 2)
Starting from an absolute on-wafer one-port calibration : Connect the HIP to the open of the on-wafer calibration kit
Starting from an absolute coaxial one-port (or two-port) calibration : Connect the HIP to the open on a microstrip or coplanar waveguide PCB
provided by NMDG De-embedding information provided with PCB allows to move the absolute
calibration from the coaxial plane to the open on the PCB
fig. 1 fig. 2
© NMDG 2012 11
High-impedance probe calibration in practice (step 2)
Connecting the “home-made” (2k4) HIPto the thru of the TRL calibration kit
© NMDG 2012 12
HIP and real-time scope : ESD (TLP) @ OnSemi
Comparing reconstructed voltage waveforms at the DUT, measured on a 7.3VZener diode, subjected to a 200V TLP pulse. Blue : reconstructed using data from the directional couplers. Red : corrected data from Kelvin-probe.
Photos and figure courtesy of Renaud Gillon (OnSemi, Oudenaarde, Belgium)
Using a calibrated Kelvin probe as part ofa transmission line pulse (TLP) system tore-construct dynamic voltage waveforms on low-impedance devices subjected tohigh currents with a very significant improvement in the signal-to-noise ratio
© NMDG 2012 13
TLP measurement setup
charge line
Tek scopeDP070404
cable1 cable2
vD
7.3 V Zener diode
x3m cable3
Kelvinprobe
http://www.ggb.com/10.html
200 V, 25 ns pulse0.6 ns rise time
WerlatoneC6493 30 dB
coupler
Kelvin probe
© NMDG 2012 14
Combined impact of Kelvin probe(*), cable3 and scope
0.2 0.4 0.6 0.8 1
37
36
35
34
0.2 0.4 0.6 0.8 1
10
8
6
4
2
2
4
0.2 0.4 0.6 0.8 11000
1250
1500
1750
2000
2250
2500
0.2 0.4 0.6 0.8 1
60
50
40
30
20
10
50:1 (nominal)
|TF| (dB)
TF (deg)
excl. delay of 8.3 ns
|Z| (Ω)
Z (deg)
freq(GHz)
freq(GHz)
freq(GHz)
freq(GHz)
transfer functionx3m / vD
impedance
2k5 (nominal)
resonanceeffect
(*) GGB – Model 10 - 2k5
© NMDG 2012 15
Primary calibration of TLP systemscope
cable1 cable2
knownDUT
vD & iD
source open short match power meter
source
scope
cable1 cable2
knownactiveDUT
x1m x2mvD & iD
pulse gen
50Ωtermination
x1m x2m
in case of on-wafer the absolute calibration is performed at an “Auxiliary” coaxial calibration plane
© NMDG 2012 16
Additional calibration of TLP system
scope
cable1 cable2
knownDUT
vD
source open
x3m cable3
Compare x3m to calibrated coupler-based vD while measuring an open Transfer function: TF = 1 / e33 = x3m / vD Measure impedance of Kelvin probe during calibration (using iD) Allows to take effect of finite impedance into account during simulation
Kelvinprobe
© NMDG 2012 17
Acknowledgements and References
NMDG wants to thank Rohde & Schwarz and OnSemi for their support
"A new time domain waveform measurement setup to investigate internal node voltages in MMICs",T. Reveyrand, A. Mallet, F. Gizard, L. Lapierre, J.M. Nébus, M. Vanden BosscheMicrowave Technology and Technique Workshop, ESTEC, Noordwijk , May 2004
"Calibrated Waveform Measurement With High-Impedance Probes",Pavel Kabos, Howard Charles Reader, Uwe Arz and Dylan F. WilliamsIEEE Transactions on Microwave Theory and Techniques,Vol. 51, No. 2, pp. 530 - 535, February 2003
"Multiport Investigation of the Coupling of High-Impedance Probes",P. Kabos, U. Arz and D. F. WilliamsIEEE Microwave and Wireless Components Letters,Vol. 14, No. 11, pp. 510 - 512, November 2004