In-Circuit Probing Presentation
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The document discusses the use of high-impedance probes for accurate in-circuit time-domain voltage measurements within large-signal network analysis. It outlines measurement setups, calibration techniques, and results demonstrating the effectiveness of high-impedance probing in capturing voltage waveforms between components. Additionally, it provides insights on using calibrated probes to mitigate measurement disturbances and improve signal quality.
In-Circuit Probing Presentation
- 1. HIP @ ICE using high-impedance probes for in-circuit voltage time-domain measurements © NMDG 2/2012
- 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 techniques How to minimize their disturbance? Use high-impedance probes © NMDG 2012 2
- 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 3
- 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 probe probe synchronizer P3 P1 P4 P2 source probes 50Ω termination 2nd calibrated HIP probe allows to measure the input voltage © NMDG 2012 4
- 5. Measurement using calibrated HIP in practice (II) v2(t) excellent agreement between output voltage (red) measured using the TRL-calibrated coupler-based two-port network analyzer and the voltage (green) measured by the calibrated high-impedance probe v2(f) corresponding excellent agreement of amplitude and phase in the frequency domain upper: coupler-based amp & phase lower: calibrated HIP amp & phase © NMDG 2012 5
- 6. Measurement using calibrated HIP in practice (III) “a global ICE perspective” © NMDG 2012 6
- 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 | ZHIP | f (GHz) 2600 0.5 1 1.5 2 2400 10 2200 20 2000 30 1800 40 1600 1400 50 f (GHz) 0.5 1 1.5 2 60 ZHIP (deg) Estimated impedance of “home-made” (2k4) HIP (*) in fact the combination of the probe, cable and receiver input © NMDG 2012 7
- 8. Including impact of high-impedance probe during simulation Probe i2 v2 v probe i1 v1 including the load effect of the probe in the simulation to compare measurements with Figure and schematic courtesy of AWR simulations © NMDG 2012 8
- 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 9
- 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 10
- 11. High-impedance probe calibration in practice (step 2) Connecting the “home-made” (2k4) HIP to the thru of the TRL calibration kit © NMDG 2012 11
- 12. HIP and real-time scope : ESD (TLP) @ OnSemi Using a calibrated Kelvin probe as part of a transmission line pulse (TLP) system to re-construct dynamic voltage waveforms on low-impedance devices subjected to high currents with a very significant improvement in the signal-to-noise ratio Comparing reconstructed voltage waveforms at the DUT, measured on a 7.3V Zener 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) © NMDG 2012 12
- 13. TLP measurement setup Tek scope DP070404 x3m cable3 200 V, 25 ns pulse 0.6 ns rise time Kelvin cable1 cable2 probe Werlatone vD charge line C6493 30 dB coupler 7.3 V Zener diode Kelvin probe http://www.ggb.com/10.html © NMDG 2012 13
- 14. Combined impact of Kelvin probe(*), cable3 and scope transfer function impedance |TF| (dB) x3m / vD |Z| (Ω) freq 2k5 (nominal) 2500 0.2 0.4 0.6 0.8 1 (GHz) 34 50:1 (nominal) 2250 2000 resonance 35 effect 1750 36 1500 1250 37 1000 freq 0.2 0.4 0.6 0.8 1 (GHz) TF (deg) Z (deg) 4 freq 0.2 0.4 0.6 0.8 1 (GHz) 2 10 freq 20 0.2 0.4 0.6 0.8 1 (GHz) 2 30 4 40 6 50 8 60 10 excl. delay of 8.3 ns (*) GGB – Model 10 - 2k5 © NMDG 2012 14
- 15. Primary calibration of TLP system scope x1m x2m vD & iD cable1 cable2 ● open source known ● short ● match scope DUT ● power meter x1m x2m ● pulse gen vD & iD cable1 cable2 50Ω known source termination active DUT in case of on-wafer the absolute calibration is performed at an “Auxiliary” coaxial calibration plane © NMDG 2012 15
- 16. Additional calibration of TLP system scope x3m cable3 Kelvin probe cable1 cable2 vD source known ● open DUT ● 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 i ) D ● Allows to take effect of finite impedance into account during simulation © NMDG 2012 16
- 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 Bossche Microwave 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. Williams IEEE 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. Williams IEEE Microwave and Wireless Components Letters, Vol. 14, No. 11, pp. 510 - 512, November 2004 © NMDG 2012 17
- 18. Contact info Want to try this capability? Contact us at info@nmdg.be © NMDG 2012 18