Large-Signal Network Analyzer Technology

Large-Signal Network Analyzer Technology
An Overview and Examples This slide set introduces the large-signal technology and the combination with tuner technology. It is demonstrated how the ATS tuners and software from Maury Microwave work together with a large-signal network analyzer and how the combination gives unprecedented amount of information what is going on at the device level.  Copyright 2003 NMDG Engineering

Agenda Why “Large-Signal Network Analysis” is needed
The Large-Signal Network Analyzer Calibration State of the art and evolution Application Examples Conclusions

Design Challenge “Customers are demanding more capabilities/performance from their devices.” Designers are looking for better methods of characterizing their components Demands translate to greater design complexities More complex modulation schemes Higher power efficiency requirements Improved linearity S 90 Phase Splitter I/Q Modulator LO I Q Rx/Tx Module Matched Transistors Transistors PA Module MCPA Mixer

Why can’t I predict component performance better?
Existing tools are insufficient Network analyzers analyze component behavior but only the small-signals (linear) behavior accurately Signal analyzers evaluate partial properties of signals interacting with the test device, they do not analyze the component behavior while interacting with the (measurement) environment To understand problems / defects faster To do more complete tests Need more realistic test conditions Need for a network analyzer approach in large-signal environments

Amplifier Measurements
AM-PM Gain Phase flatness ACPR Power Added Efficiency Device Under Test Loadpull

ACPR of an MCPA PASS FAIL
Build two MCPAs, one passes the other does not Do you know what to fix? ACPR and other measurement data only represent symptoms of the problem No insight is provided as to the cause of the problem PASS FAIL

Insufficient Tools for a proper design / test process
Model Simulate Build Meas Ideal: Measurements correlate with simulations In a linear environment, S-Parameters are an excellent example The real world for non-linear characterization: Insufficient models Incomplete information Poor correlation between measurements and simulations Model Simulate Build Meas S-P ACPR Power =

Results Cut-and-try engineering (designers “imagineer” fixes)
Design verification consumes 2/3rds of development time Time-to-market delays Unpredictable design processes Time consuming tuning and measurement requirements

Agenda Introduction Large-Signal Network Analysis
The Large-Signal Network Analyzer Calibration Application Examples Conclusions

Small-Signal Network Analysis
Linear Behavior Test signal : simple, typically a sine wave Superposition principle to analyze behavior in realistic conditions Network Transistor, RFIC, Basestation Amplifier, Communication system Analysis Complete component characterization : S - parameters (within measurement bandwidth) Small - signal behavior refers to a stimulus so small that they keep the component under test in its linear region of operation. In that region, a simple test signal (typically a frequency - stepped sine wave) can be used to collect an accurate and complete picture of the device behavior within the measurement bandwidth because of the superposition principle. Small-signal network analysis is independent of the type of component and independent of the process technology. It can be applied from transistor level up to the system level. The S-parameters are the mathematical tool to describe the linear behavior adequately. These parameters can be measured easily with a vector network analyzer within its frequency range.

Large-Signal Network Analysis
Refers to potential nonlinear behavior Nonlinear behavior  Superposition is not valid Requirement: Put a DUT in realistic large-signal operating conditions Network Transistor, RFIC, Basestation Amplifier, Communication system Analysis Characterize completely and accurately the DUT behavior for a given type of stimulus Analyze the network behavior using these measurements Small-signal network analysis implies that the signal levels are so small that the device behaves linearly. Many applications today require the usage of signal levels which are significantly higher, e.g. power amplifiers, driving the devices in their nonlinear region of operation. At that moment, S-parameters are not sufficient anymore and there is a need to “go beyond S-parameters”. As soon as the device behaves nonlinear, the superposition principle is not valid anymore. Also there does not exist a general nonlinear theory that tells how to analyze and how to characterize nonlinear devices in general. The idea is to extend the boundaries of linear device analysis step by step. It is presently assumed that the boundaries will be dictated by the classes of signals that the DUT will experience in its application, for example CDMA, GSM etc … Also it will be required to put the device-under-test (DUT) under realistic large-signal operating conditions and to acquire complete and accurate information of its electrical behavior for these classes of signals. Having the right (behavioral modeling) tools to interpolate between the measurements, it is then possible to analyze the network behavior. The goal is to develop these techniques independent of the device type (transistor, module …). To analyze the device behavior using the large-signal characteristics CAE tools will be helping to eliminate the increased complexity of dealing with nonlinear behavior instead of linear behavior.

Large-Signal Network Analysis: Overview
Measurement System Realistic Stimulus Realistic Stimulus Transistor RFIC System Representation Domain Frequency (f) Time (t) Freq - time (envelope) The first step in small- and large-signal network analysis is to define the network or in other words the ports that define the boundaries of the device with the external world. Secondly different choices (voltage / current and incident / reflected waves) need to be made for the representation of the acquired data. The best choice will depend on the application. Process engineers and transistor modelers tend to work more with voltage and current formalism while system engineers will work with waves. Finally the time, frequency or frequency - time domain can be used to represent the signals. Again process and transistor modeling engineers tend to prefer the time domain because their models are formulated in the time domain, while system engineers do prefer the frequency domain because of the system level specifications like ACPR, spectral re-growth … The measurements at the component ports (after elimination of instrument interaction) are related to each other through the component behavior. This relation can be expressed by a series of equations in time or frequency domain using voltages / currents or waves. The realistic operating conditions are typically achieved by stimulating the device with synthesizers and by using tuning techniques. Physical Quantity Sets Travelling Waves (A, B) Voltage/Current (V, I) Analysis

Representation Domain: Limited to Multi - tones
All voltages and currents or waves are represented by discrete tones (including DC) X1 Xi ... X0 Xk Xl ... Freq. (GHz) Freq. (GHz) DC DC Z1 DUT Z2 ... Freq. (GHz) DC The simplest measurement solution deals with continuous wave one-tone excitation of 2-port devices, e.g. a biased FET-transistor excited by a CW signal (for example at 1 GHz) at the gate, with an arbitrary load at the drain. Assuming that the device is stable (not oscillating) and does not exhibit subharmonic or chaotic behavior, all current and voltage waveforms will have the same periodicity as the drive signal (in this case 1 ns). This implies that all voltage and current waveforms (or the associated travelling voltage waves) can be represented by their complex Fourier series coefficients. These are called the spectral components or phasors. (One calls the 1GHz component the fundamental, the 2GHz component the 2nd harmonic, the 3GHz component the 3rd harmonic,…) The DC components are called the DC-bias levels. In practice there will only be a limited number of significant harmonics. The measurement problem is as such defined as the determination of the phase and amplitude of the fundamental and the harmonics, together with the measurement of the DC-bias. The set of frequencies at which energy is present and has to be measured is called “the frequency grid”. All frequencies of the grid are uniquely determined by an integer (h), called the “harmonic index”, compared to the fundamental frequency or the carrier. Complex Fourier coefficients Xh of waveforms ... ... Freq. (GHz) Freq. (GHz) DC DC

Waves (A, B) versus Current/Voltage (V, I)
Typically As we said before, the “large-signal analyzer” will return the measured data as a port current (noted I) and a port voltage (noted V), or as an incident (noted A) and a scattered (noted B) travelling voltage wave at that port. Since we assume that we are dealing with a quasi-TEM mode of propagation the relationship between both sets of quantities is given by the simple linear transformation represented above. A-B representations are typically used for near matched and distributed applications (system amplifier). V-I representations are typically used for lumped non-matched applications (individual transistors). In most cases a characteristic impedance of 50 Ohms is used for the wave definition. For certain applications, however, other values can be more useful. In general, Zc can be frequency dependent. An example is the black-box modeling of the behavior of a power transistor. In this case it is convenient to represent the fundamental at the output in an impedance which is close to the optimal match (typically a few Ohms). “From device to system level”

Small-Signal Network Analysis: S-parameters
Measurement System Measurement System Transistor RFIC System Transistor RFIC System Experiment 1 Experiment 2 To measure the S-parameters of a device, the network analyzer needs to perform two separate measurements of ratios of incident and reflected waves under the stimulus of a single tone. At first, the single tone is applied at the input while the device is terminated in 50 Ohms. Secondly the single tone is applied to the output while the input is terminated into 50 Ohms. Finally these measured ratios are processed (= solving a linear equations) to result into the S-parameters at the frequency of the single tone. These S-parameters are a measurement-based behavioral model of the device under test. Finally when a VNA plots the S-parameters as function of frequency, it uses a very lite simulator to interpolate the calculated S-parameters at a discrete frequency grid. Usually it uses linear interpolation between the measured frequencies. Large-signal analysis is similar but requires more experiments (close to realistic operating conditions) to provide a measurement - based behavioral model. Analysis

Large-Signal Network Analysis
Measurement System Realistic Stimulus Realistic Stimulus Transistor RFIC System Different Experiments The realistic operating conditions are typically achieved by stimulating the device with synthesizers and by using tuning techniques. Different choices (voltage / current and incident / reflected waves) can be (need to be) made for the representation of the acquired data. The best choice will depend on the application. Process engineers and transistor modelers tend to work more with voltage and current formalism while system engineers will work with waves. The measurements at the component ports (after elimination of instrument interaction) are related to each other through the component behavior. This relation can be expressed by a series of equations in time or frequency domain using voltages / currents or waves, expressing the DUT behavior. A complete measurement, returned by the LSNA, is one realization of this set of equations, enforced by the interaction of the environment with the DUT. Therefore the voltage - current or wave combination at all ports are defining the state of the device in a unique way. When one would be able to perform infinite number of measurements by changing the environment, one would end up with an infinite table of realizations of these equations, describing this device completely. Of course taking infinite number of measurements will take an infinite amount of time. The challenge for measurement - based behavioral models is to perform a limited set of experiments which can be interpolated with confidence within a well defined set of boundaries of operating conditions, like the type of signals. Analysis

Component Characterization under large-signal conditions
LSNA Technology Simulation Simulation Tools Measurement Modeling DUT LSNA technology is about bringing accurate and complete characterization of components (with the elimination of uncertainty of systematic errors from the instrumentation) together with simulation tools through measurement-based behavioral models. Or in other words it is about bringing measurements of a component alive in a simulation tool resulting in more accurate predictions. Measurement-based Behavioral Models Accurate and Complete Component Characterization under large-signal conditions

Vector Network Analyzer Measurement
Response 50 Ohm Acquisition Stimulus Reference Planes Calibration In fact a vector network analyzer is a complete measurement system, containing internally an experiment generation and model extraction capability. The experiment generation consists of a forward and reverse excitation and measurement of the component under test. The model extraction refers to the equation solving using the measurements, resulting into S-parameters. The vector network analyzer contains a test - set to separate incident from reflected waves, an acquisition system for uncalibrated measurements and a microwave source. Restricting its usability to linear components and based on the S-parameter theory, a vector network analyzer can internally apply a signal once to the input and once to the output of the device. From these measurements it can calculate the S-parameters using some calibration technique to eliminate the systematic errors introduced by the system. This can be repeated at each frequency of interest to predict the behavior under a rich set of signals within the measurement bandwidth. S-parameters Linear Theory

Large-Signal Network Analyzer
Response Acquisition Stimulus Modulation Source 50 Ohm or tuner Reference Planes Calibration The Large-Signal Network Analyzer looks similar to a vector network analyzer. There is a broadband test - set to separate incident and reflected waves. A microwave source or a vector signal generator can inject a one tone or periodic modulated signal into the component under test. If this component is nonlinear, it will generate harmonics in its reflection and transmission. These harmonics are reflected back by the mismatch created by the measurement system. A broadband acquisition system is able to take proper samples of these broadband incident and reflected waves. To create realistic operating conditions it is possible to connect to the system passive or active source and load impedance tuners. In contrast to the VNA, where the source is an integral part of the measurement system, the LSNA is a calibrated data acquisition system with a lot of freedom related to the excitation scheme. The main restriction is that all sources must be synchronized from the reference clock. Remark also that the measurement system is AC coupled towards the stimulus at port 1 and at port 2. This prevents the flow of DC current towards the stimulus. One needs to be aware that this enforces possibly a certain DC condition on the device under test when it is not AC coupled by itself. With the proper calibration techniques, the systematic errors of the measurement system are eliminated. The complete spectrum (amplitude and phase) of incident and reflected waves can be acquired and the time waveforms reconstructed. Complete Spectrum Waveforms Harmonics and Periodic Modulation

LSNA System Block Diagram
Source Sampling Converter Filter Filter DUT Interface Test Set PC Data-Acquisition DUT Filter Filter 10 MHz IF Cal Kit LO Power Std 2nd Source / Tuner Phase Std

Practical Limitations of LSNA
Large-Signal Network analysis will be performed using periodic stimuli one - tone and harmonics periodic modulation and harmonics other types of multi - tones are possible The devices under test maintain periodicity in their response Due to restrictions enforced by the practical measurement implementations for the large-signal characterization of RF and microwave components, only periodic stimuli will be considered to study the behavior of components. Typically for telecommunications the signals will consist of a carrier and harmonics and are periodic as such and periodic modulation. For wireline applications these will be periodic bitstreams. We also will study only devices that maintain periodicity. So we will not consider oscillators, neither devices with chaotic behavior.

Representation Domain: Continuos Wave Signal
All voltages and currents or waves are represented by a fundamental and harmonics (including DC) X1 X2 X0 X4 X3 Freq. (GHz) Freq. (GHz) 1 1 DC 2 3 4 DC 2 3 4 Z1 DUT Z2 Freq. (GHz) 1 DC 2 3 4 The simplest measurement solution deals with continuous wave one-tone excitation of 2-port devices, e.g. a biased FET-transistor excited by a CW signal (for example at 1 GHz) at the gate, with an arbitrary load at the drain. Assuming that the device is stable (not oscillating) and does not exhibit subharmonic or chaotic behavior, all current and voltage waveforms will have the same periodicity as the drive signal (in this case 1 ns). This implies that all voltage and current waveforms (or the associated travelling voltage waves) can be represented by their complex Fourier series coefficients. These are called the spectral components or phasors. (One calls the 1GHz component the fundamental, the 2GHz component the 2nd harmonic, the 3GHz component the 3rd harmonic,…) The DC components are called the DC-bias levels. In practice there will only be a limited number of significant harmonics. The measurement problem is as such defined as the determination of the phase and amplitude of the fundamental and the harmonics, together with the measurement of the DC-bias. The set of frequencies at which energy is present and has to be measured is called “the frequency grid”. All frequencies of the grid are uniquely determined by an integer (h), called the “harmonic index”, compared to the fundamental frequency or the carrier. Complex Fourier coefficients Xh of waveforms Freq. (GHz) Freq. (GHz) 1 1 DC 2 3 4 DC 2 3 4

Representation Domain: Amplitude and Phase Modulation of Continuos Wave Signal
X1(t) Amplitude X2(t) X0(t) X4(t) Phasor Freq. (GHz) Freq. (GHz) 1 1 Modulation time DC 2 3 4 time DC 2 3 4 X3(t) Slow change (MHz) Z1 DUT Z2 Fast change (GHz) Freq. (GHz) 1 time DC 2 3 4 Suppose now that we change the amplitude and phase of the one - tone source over time. As effect we will see all spectral components of the signals at the component under test change over time. This results for each phasor in a complex time signal. One will see that the DC will start to change over time. This is referred to as dynamic bias. To detect the time-varying spectral components properly (without leakage), it is necessary to make the modulation periodic. Complex Fourier coefficients Xh(t) of waveforms Freq. (GHz) Freq. (GHz) 1 1 time DC 2 3 4 time DC 2 3 4

Representation Domain: Periodic Modulated Signals
Phase X1i Amplitude X0i Phasor X2i X3i Freq. (GHz) Periodic Modulation 1 Freq. (GHz) 1 DC 2 3 DC 2 3 Z1 DUT Z2 Freq. (GHz) 1 DC 2 3 4 As an example, consider the same FET transistor whereby one modulates the 1GHz signal source, such that the modulation has a period of 10kHz. Therefore, the phasors will be complexe time functions, as explained in previous slide, but with a periodicity of 10 kHz. So, it is now possible to apply a Fourier transform on the compexe time signal of each phasor. Therefore the voltage and current waveforms will now contain many more spectral components. New components will arise at integer multiples of 10kHz offset relative to the harmonic frequency grid. In practice significant energy will only be present in a limited bandwidth around each harmonic. The resulting set of frequencies is called a “dual frequency grid”. Note that in this case each frequency is uniquely determined by a set of two integers, one denoting the harmonic frequency, and one denoting the modulation frequency. E.g. harmonic index (3,-5) denotes the frequency 3GHz - 50kHz. The measurement problem will be to determine the phase and the amplitude of all relevant spectral components of current and voltage. Complex Fourier coefficients Xhm of waveforms Freq. (GHz) 1 1 Freq. (GHz) DC 2 3 DC 2 3 … extendable to any type of multi-tone signal

Harmonic Sampling - Signal Class: Continuous Wave
LP fLO=19.98 MHz = (1GHz-1MHz)/50 RF 50 fLO 100 fLO 150 fLO 1 2 3 IF Bandwidth IF 1 2 3 Freq. (MHz)

Harmonic Sampling - Signal Class: Narrowband Modulation
LP fLO=19.98 MHz = (1GHz-1MHz)/50 RF 50 fLO 100 fLO 150 fLO 1 2 3 IF IF Bandwidth 1 2 3 Freq. (MHz)

Harmonic Sampling - Signal Class: Broadband Modulation
LP BW 2BW MHz Adapted sampling process BW RF 150 fLO 1 2 3 Freq. (GHz) IF Freq. (MHz) BW of Periodic Broadband Modulation = 2* BW IF data acquisition

LSNA Calibration Acquisition Response Stimulus Reference Calibration
F0=1GHz Stimulus Modulation Source 50 Ohm or tuner Reference Planes Calibration Actual waves at DUT With the proper calibration techniques, the systematic errors of the measurement system are eliminated. The complete spectrum (amplitude and phase) of incident and reflected waves can be acquired and the time waveforms reconstructed. During an experiment we want to know the phases and amplitudes of a discrete set of spectral components at the DUT signal ports. These quantities are called the ”DUT quantities” and are denoted by a superscript “DUT”. Unfortunately we do not have direct access to these quantities. The only information we can get are the uncalibrated measured values. These are called the “raw measured quantities” and are denoted by a superscript “m”. Because the Large-Signal Network Analyzer is linear by itself in operation, a linear relationship exists between the raw measured quantities and the DUT quantities. This relationship is expressed in a 4x4 matrix. This matrix is a function of the frequency and is typically calculated on the fundamental and harmonics. The K-factor of the matrix requires a power meter (amplitude of K) and a reference generator (phase of K). Measured waves 1GHz 2GHz 3GHz 7 relative error terms same as a VNA freq Absolute magnitude and phase error term

Relative Calibration: Load-Open-Short
Acquisition {f0, 2 f0, …, n f0} Load Open Short 50 Ohm 50 Ohm {f0, 2 f0, …, n f0} f0 = 1GHz Acquisition The relative calibration is exactly the same as for a vector network analyzer. Referring to an example where one wants to characterize a transistor on a frequency grid of 1 GHz with 20 harmonics, the microwave source is stepped in steps of 1 Ghz from 1 GHz to 20 GHz and measuring the S-parameters of known linear devices (load, opens, short, thru). 50 Ohm Thru 50 Ohm Calibration for all multi - tones

Power Calibration Acquisition {f0, 2 f0, …, n f0} Power Meter 50 Ohm
freq 1GHz 2GHz 3GHz Amplitude {f0, 2 f0, …, n f0} Acquisition {f0, 2 f0, …, n f0} Power Meter 50 Ohm f0 = 1GHz For the power calibration a power meter is connected to “Port 1” of the system. The source is stepped through the frequency grid (in our example from 1 GHz to 20 GHz in steps of 1 GHz). For each step the power is measured and calculated through the acquisition system. This results into a distortion table as function of the frequency. Measuring on wafer, the calibration reference planes correspond to the probe tips. Therefore, “Port 1” is connected to “Port 2” via a line on wafer and an additional load-open-short calibration is done at the port with the 50 Ohm load while stepping the source in steps of 1 GHz. Then the power meter is connected at that point and the source is stepped again. With some calculations and the reciprocity principle the power can be referred back to “Port 1”.

Phase Calibration Acquisition ... f0 Harmonic Phase 50 Ohm 50 Ohm
freq 1GHz 2GHz 3GHz Phase {f0, 2 f0, …, n f0} Acquisition f0 ... 50 Ohm Harmonic Phase Reference 50 Ohm For the phase calibration a reference generator is connected to “Port 1” of the LSNA. The source generates one tone at 1 GHz. The reference generator is a pulse generator with a repetition rate of 1 GHz. In the frequency domain this corresponds to spectral components on a frequency grid of 1 GHz. At manufacturing time, Agilent Technologies is capable of calibrating this generator very accurately and traceably in phase as function of generated harmonic with the nose nose calibration process. f0 f0 = 1GHz

Measurement Traceability
Relative Cal Phase Cal Power Cal Agilent Nose-to-Nose Standard (*) For now, the relative calibration and the power calibration of the LSNA are traceable to national standard labs. The phase calibration is traceable to a nose-to-nose standard, developed at Agilent but licensed to Maury and NMDG. Since some time, the NIST is investigating the whole phase calibration process. National Standards (NIST) (*) Licensed to Maury and NMDG

State of the art + From ... … To Scope LSNA Signal Characterization
Component Characterization + Complete Accurate

For the scientific customer ...
You are NOT buying 1 instrument You are buying unique FOUNDATIONS to build a new type of house in the RF/microwave scientific community to develop new theories, approaches resulting in scientific recognition to impact as the S-parameters the way the engineer designs and tests to actively contribute to the LSNA users group New horizons to modeling designing testing Component Characterization

For the industrial customer ...
You are NOT buying 1 instrument You are buying into a technology enabling you to see what your competitor cannot see creating a competitive advantage for you while working with us towards solutions to your problems evolving through software and hardware upgrades “We work with you” Component characterization Model verification Model tuning S-parameters under CW S-parameters under modulation conditions Hot S-parameters Hot stability Conversion matrices Scattering functions Memory effects ... Component Characterization

Examples Transistor reliability
Transistor model verification (ICCAP / ADS) Transistor model tuning System level characterization Scattering functions Memory effect Dynamic bias High-Speed digital PA design using waveform engineering

Gate-Drain Breakdown Current
Time (ns) º TELEMIC / KUL º transistor provided by David Root, Agilent Technologies - MWTC

Forward Gate Conductance
Time (ns) º TELEMIC / KUL º transistor provided by David Root, Agilent Technologies - MWTC

Model Verification in CAE tool
ADS Model Measured Incident Waves Multi-line TRL Measured and Simulated Voltages and Currents

LSNA Measurements in ICCAP: 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

Transistor De-embedding
Equivalent circuit of the RF test-structure, including the DUT and layout parasitics before de-embedding after Gate current / mA Time/period

Input capacitance behavior
Vgs,dc=0.9 V Vds,dc=0.3 V Vds,dc=1.8 V Input loci turn clockwise, conform i=C*dv/dt

Dynamic loadline & transfer characteristic
Vds,dc=0.9 V Vgs,dc=0.3 V

Identifying modeling problems: extrapolation example SiGe HBT ...
100 200 300 400 500 600 700 800 900 -0.002 -0.001 0.000 0.001 -0.003 0.002 time, psec i1sts i1mts_de 0.6 0.7 0.8 0.9 1.0 1.1 0.5 1.2 v1sts v1mts_de 1.3 1.4 1.5 1.6 1.7 v2sts v2mts_de 0.004 0.006 0.008 i2sts i2mts_de simul. meas. SiGe HBT (model parameters extracted using DC measurements up to 1V) Vbe= 0.9 V; Vce=1.5 V; Pin= - 6 dBm; f0= 2.4 GHz

… Identifying modeling problems: extrapolation example SiGe HBT
SiGe HBT - DC characteristics 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0.0 1.6 -0.010 -0.005 0.000 0.005 0.010 0.015 0.020 -0.015 0.025 VbDC DCmeas1..Ice i2.i Measurement Simulation Alcatel Microelectronics and the Alcatel SEL Stuttgart Research Center teams are acknowledged for providing these data.

Empirical Model Tuning
Parameter Boundaries GaAs pseudomorphic HEMT gate l=0.2 um w=100 um MODEL TO BE OPTIMIZED “Chalmers Model” generators apply LSNA measured waveforms “Power swept measurements under mismatched conditions” º Dominique Schreurs, IMEC & KUL-TELEMIC

Using the Built-in Optimizer
During OPTIMIZATION Voltage - Current State Space voltage current gate drain gate drain Time domain waveforms Frequency domain

Verification of the Optimized Model
AFTER OPTIMIZATION Voltage - Current State Space voltage current gate drain gate drain Time domain waveforms Frequency domain

Transistor model verification (ICCAP / ADS) Transistor model tuning System level characterization Scattering functions Memory effect Dynamic bias High Speed Digital PA design using waveform engineering

RFIC Amplifier Characterization using periodic modulation
Source E1 f0 = 1.9 GHz Evaluation Board A1 shows spectral regrowth Spectral regrowth on b1 combined with measurement system mismatch Nonlinear pulling on source a1 5 dB E1

Transmission Characteristics
Carrier Modulation A1 B2 Carrier Modulation Harmonic Distortion Compression Carrier Modulation 3rd harmonic Modulation

Reflection Characteristics
Carrier Modulation A1 B1 Carrier Modulation Harmonic Distortion Expansion Carrier Modulation 2nd harmonic Modulation 3rd harmonic Modulation

Scattering Functions Provide component understanding
Enable coupling in CAE tools @ fundamental frequency @ higher harmonics

Nonlinear behavior and Scattering Functions
Functions of (and independent bias settings) Index of: Port & harmonic Note: a’s and b’s are phase normalized quantities !! As shown before: for small-signal levels (linear) this reduces to (fundamental at port 2)

variation versus input power
Scattering Functions variation versus input power

Generated reflection coefficients at port 2 at f0
Generated ’s (a) ’s for verification meas.

Measured and simulated b-waves
Time domain waveforms Measured and simulated b-waves

Application of CDMA-like signal

Frequency domain fc=2.45 GHz, f  50 kHz, modulation BW  1.45 MHz
red=measured, blue=model

Time domain Memory effects !

DUT behavior under 2 - Tone excitation
Memory effects DUT behavior under 2 - Tone excitation Modulation frequency = 20 kHz Modulation frequency = 620 kHz

What is “Dynamic Bias Behavior”?
Input Voltage Output Current DC 1 Freq. (GHz) DC 1 2 Freq. (GHz) Dynamic Bias Behaviour Frequency Domain: Generation of Low Frequency Intermodulation Products Time Domain: “Beating” of the Bias

Dynamic Bias: Measurement Principle
Supply Computer Bias 2 Supply Current Probe Dynamic Bias Data Acquisition Current Probe RF Data Acquisition TUNER

RFIC Example in Time Domain
“MultiLine TRL” Input Voltage Waveform (V) Normalized Time Output Current Waveform (without Dynamic Bias) (mA) Normalized Time

Adding Measured Dynamic Bias
Dynamic Bias Current Waveform (mA) Normalized Time Output Current Waveform (including Dynamic Bias) (mA) Normalized Time

High-Speed Digital Measurements
System Risetime 7ps Compare 12ps for 50GHz scope Some Gibbs phenomenon No (random) jitter No slow tail cable response corrected DUT: 40 Gb Data Amp at 1.25 GB/s

Bitstream measurement
Scope/LSNA comparison highlights difference

Eye diagram measurement at 10 GB/s

LSNA and ATS tuners Practical solution based on passive tuners …
Broadband Receiver Source Tuner Load Tuner Fixture Termination or Second source Practically with passive tuners the tuners need to be as close to the device under test. This complicates the calibration process because one needs to take the changing tuner characteristics into account. On top of that the device under test can be a transistor on a fixture. Therefore one needs also to de-embedd the fixture. … to minimize losses

Calibration process in 1-2-3
LSNA Raw1 Broadband Receiver Raw2 Load Tuner Source Tuner Fixture Termination or Second source P1 T1 T1 D1 D2 T2 T2 P2 Step 1: Absolute calibration in DUTi plane (tuner in Z0 position) = Di  Rawi (tuner at Z0) Step 2: SOL calibration (no THRU required) in Tuneri plane (tuner in Z0 position) = Ti  Rawi (tuner at Z0) Step 3: Tuner characterization (S-parameters) for all positions of interest = Ti  Pi ( tuner positions, incl. Z0) In the ATS-LSNA software a calibration process is implemented that requires the proper characterization of the tuners at the different useful positions for the frequencies of interest. Due to the stability of the Maury tuners, these files can be used for a long time. Additionally one needs to perform an absolute calibration in the device plane and a simple SOL (not thru) at the planes of the tuners. Proper combination of the above 3 steps allows to obtain fully calibrated data for any tuner position: Di  Rawi (at any tuner position of interest)

ATS - LSNA Use: Calibration Support
SOLT LRRM Here one sees the known ATS interface in combination with some dialogue boxes used during the calibration of the LSNA. Presently SOLT and LRRM is supported and consulting can be delivered for multiline TRL. The advantage for multiline TRL is to be able to calibrate up to the level of the RFIC.

Load-pull measurements on RFIC Amplifier
Here one can see an overlay of the DC I/V curves with a dynamic loadline with a load close to a short.

Measurement Representations
The accurate voltages and currents or incident and reflected waves measured and calibrated up to the DUT plane, can be visualized in different ways.

Conclusions Explanation of
Large-Signal Network Analysis concepts Block diagram,instrument and calibration process A limited set of examples LSNA opens complete new horizons to improve the design and testing process in different ways when nonlinear behavior is envolved Contact Marc Vanden Bossche

Large-Signal Network Analyzer Technology

Similar presentations

Presentation on theme: "Large-Signal Network Analyzer Technology"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Large-Signal Network Analyzer Technology

Similar presentations

Presentation on theme: "Large-Signal Network Analyzer Technology"— Presentation transcript:

Similar presentations

About project

Feedback