Stability under Large-Signal Conditions Presentation
0 likes651 views
The document discusses the importance of combining large-signal and small-signal measurements using a vector network analyzer for characterizing amplifiers and assessing stability. It outlines practical setups, measurement techniques, and the impact of spurious and interference signals, emphasizing the value of s-parameters in analyzing amplifier behavior. Conclusions highlight the simplicity of using a Rohde & Schwarz network analyzer for achieving comprehensive insights into both small-signal and large-signal conditions.
![Block Diagram
Measure at large-signal frequency grid and
at small-signal frequency grid, sweeping source 2
Network Analyzer Receivers
Large Signal ` (*) (*)
Conditions
ZS
f0 DUT
External RF source 1 ZL
or
VNA RF source 1 “Measure S-par” 50 Ohm
Large Signal
(depends on VNA)
Conditions
VNA couplers
or VNA RF source 2
external (low-loss) couplers [similar to S-par measurement]
Absolute Calibration Planes
(*) Other configurations possible, e.g. position couplers, use of splitters,
depending on power requirements
© NMDG 2012 5](https://image.slidesharecdn.com/stabilityunderlargesignalconditionspresentation-120619170954-phpapp01/85/Stability-under-Large-Signal-Conditions-Presentation-5-320.jpg)
Stability under Large-Signal Conditions Presentation
- 1. Spurious and Stability Analysis under Large-Signal Conditions using your Vector Network Analyser An application of ICE June 2012
- 2. Outline ● Why combining Large-Signal and Small-Signal Measurements ● Block Diagram ● Practical Setup ● S-parameters ● Stability Criteria ● Large-Signal Measurements ● References and Acknowledgements ● Conclusions © NMDG 2012 2
- 3. Why combining Large-Signal and Small-Signal Measurements How to quantify impact from … ? SPURIOUS SIGNALS INTERFERENCE S-parameters, usually measured under small-signal conditions, provide ● good insight in the linear behaviour of a amplifiers ● provide insight in the stability of the amplifier S-parameters, measured under large-signal conditions, provide ● good insight in what happens with spurious signals and interference signals © NMDG 2012 3
- 4. Why combining Large-Signal and Small-Signal Measurements Under different large signal conditions … what about … ? STABILITY ZS ZL S-parameters, usually measured under small-signal conditions, provide ● good insight in the linear behaviour of a amplifiers ● provide insight in the stability of the amplifier S-parameters, measured under large-signal conditions, provide ● provide insight in the stability of the amplifier as conditions change © NMDG 2012 4
- 5. Block Diagram Measure at large-signal frequency grid and at small-signal frequency grid, sweeping source 2 Network Analyzer Receivers Large Signal ` (*) (*) Conditions ZS f0 DUT External RF source 1 ZL or VNA RF source 1 “Measure S-par” 50 Ohm Large Signal (depends on VNA) Conditions VNA couplers or VNA RF source 2 external (low-loss) couplers [similar to S-par measurement] Absolute Calibration Planes (*) Other configurations possible, e.g. position couplers, use of splitters, depending on power requirements © NMDG 2012 5
- 6. © NMDG 2012 6
- 7. Practical Setup Bias External RF Source 1 ICE Using VNA couplers Termination FET Gate bias: -1.2 V (class A) Drain bias: 4 V Increasing input power and different terminations © NMDG 2012 7
- 8. “Channel” capability of the ZVA 24 Using Rohde&Schwarz ZVA capability to configure different “channels” Each channel has his own specific hardware configuration measured data The Rohde&Schwarz ZVA switches fast from channel to channel ZVA24 Display Large-Signal Measurements Small-Signal Measurements © NMDG 2012 8
- 9. S-parameters under different large-signal conditions S11 dB S12 NO RF signal dB 0 dBm (load) freq GHz 5 dBm (load) 2 4 6 8 10 15 5 dBm (open) 1 20 2 3 25 4 freq GHz 2 4 6 8 10 5 S21 S22 dB dB 20 30 10 20 freq GHz 2 4 6 8 10 10 10 freq GHz 2 4 6 8 10 20 10 30 © NMDG 2012 9
- 10. Stability K-Factor and Determinant Abs U Determinant Abs U Kfact 1.0 1.0 0.8 0.6 0.5 0.4 freq GHz 0.2 2 4 6 8 10 freq GHz 2 4 6 8 10 0.5 NO RF signal Stability Conditions 0 dBm (load) 5 dBm (load) ∣K∣1 and ∣∣1 5 dBm (open) © NMDG 2012 10
- 11. Input and Output Stability Circles Input Output 5 dBm (load / open) NO RF signal 0 dBm (load) X1.0 R0 X1.0 R0 X0.5 X2.0 X0.5 X2.0 R0.5 R0.5 R1.0 R2.0 R1.0 Stable X0 R2.0 X0.5 X2.0 X1.0 X0 5 dBm (load / open) Stable NO RF signal X0.5 X2.0 X1.0 0 dBm (load) Frequency: 4.2 GHz © NMDG 2012 11
- 12. Large-Signal Conditions while measuring S-parameters v2t v1t Amp V Amp V time ns 8 0.5 1.0 1.5 2.0 0 dBm (load) 0.5 6 5 dBm (load) 5 dBm (open) 1.0 4 1.5 2 2.0 time ns i2t 0.5 1.0 1.5 2.0 i1t Amp A Amp A 0.010 0.25 0.20 0.005 0.15 time ns 0.5 1.0 1.5 2.0 0.10 0.005 0.05 time ns 0.010 0.5 1.0 1.5 2.0 © NMDG 2012 12
- 13. References and Acknowledgements ● “A New Characterization Technique of “Four Hot S-parameters” for the Study of Nonlinear Parametric Behaviors of Microwave Devices”, T. Gasseling, D. Barataud, et alii, 2003 IEEE MTT-S Digest, p. 1663 ● Thanks to Rohde & Schwarz for providing the R&S ZVA network analyzer equipment and the support around the network analyzer ● Thanks to Focus Microwaves for providing the tuners and the good cooperation © NMDG 2012 13
- 14. Conclusions ● It is straightforward with a Rohde & Schwarz network analyzer to measure the small-signal behaviour while applying and measuring the large-signal conditions ● With the S-parameters it is possible to get better insight when spurious signals are applied to the component or interference signals are picked up, e.g. RF front-end picking up signals ● The S-parameters result in different stability criteria. This is evenly important as the large-signal performance, designing active circuits, like amplifiers For more information info@nmdg.be www.nmdg.be © NMDG 2012 14