IQSTAR’s Key features

  • Turnkey software solution for RF circuit characterization
  • Fully customizable with flexible setup schematic
  • Instrument agnostic solution
  • No programming skills required

IQSTAR 1.3 Modules

Benefits
  • Re-use of existing hardware in the lab
    • A cost-effective testing solution
    • Quicker development time and faster time to Market
    • Less downtime and reduced maintenance costs

 

  • Faster test times
    • Automatize your tests
    • Combine multiple measurements types
    • Single calibration, multiple measurements

 

  • High Accuracy
    • Proven calibration process
    • Vector and scalar calibration available
    • Embedded validation and verification procedures
  • Flexible setups
    • Great adaptability to future test requirements
    • Instrument driver wizard for new hardware
    • Multi-brand instruments setups supported.

This module represents the basic plugin of IQSTAR and the prerequisite for other measurement modules. It includes all the configuration capabilities needed to initialize a setup and ensure proper measurement conditions of the DUT.

 


 

Schematic Editor

IQSTAR is a turnkey software with a versatile and customizable schematic editor for building a test bench with available laboratory instruments.

Multiple test configurations are possible depending on the measurements required. IQS100B-10 supports a scalar setup with various configurations. In addition, devices and circuits can be coaxial, fixtured or on-wafer. Each instrument selected in the setup can be controlled using specific drivers allowing full automation of the measurements. With 15 years of device characterization software development, AMCAD masters instrument controls and provides drivers that optimize the measurement speed without sacrificing accuracy. Each instrument can be set with different options and in different modes.

Scalar Setup

 


 

Chronogram

High-power devices require measurements in pulsed mode to mitigate thermal effects. However, pulsed options often add complexity to settings. Therefore, IQSTAR provides a simple user interface for full control of the pulse generators, the receivers, and the trigger signals. In addition, different instruments in the setup can be set with appropriate timings for the pulse setting and pulse measurements. To simplify the task for the end-user, IQSTAR embeds a Chronogram that describes, on a time axis, the pulse mode settings and a configuration panel where all the timing specifications can be set at once.

Chronogram

All instruments in pulsed mode are automatically showing up in the appropriate section of the chronogram: generators (RF signal Generators, DC supplies) and receivers (VNA, Multimeters, Power-Meters).
The measurement windows can be configured for each receiver, and once the chronogram is closed, all the settings are configured automatically in the appropriate instruments.

 


 

DC supplies

Power amplifier measurements can be particularly challenging when dealing with multistage circuits. IQSTAR allows the control of up to 20 Power supplies with associated IV measurements either from the power supplies or using DC multimeters and oscilloscopes. The flexibility of the DC power supply settings allows custom labeling of each instrument and its associated IV parameters to simplify the biasing procedure of multistage circuits. A resistive network can also be configured to de-embed the measurements and the voltage settings to the DUT reference plane in case of current or voltage drop through serial or parallel resistances. Customized formulas can be defined to calculate power consumption.

 


 

Calibration

IQSTAR provides corrected data at the DUT reference plane. The correction terms are calculated during the calibration process using a step-by-step wizard. Depending on the setup configuration, different calibrations can be performed.
For scalar setups, the calibration procedure is based on power measurements using power meters and signal generators. It is possible to calibrate the setup using two (2) or three (3) power meters to include the reflected power. A three power-meters setup permits to characterize the DUT with additional parameters like Operating Gain (Gp), delivered input power and power-added efficiency (PAE).

 


 

Spectrum Mode

The Spectrum Mode is enabled automatically if the setup includes a Spectrum Analyzer.
The Spectrum mode consists of measuring the spectrum traces for each power step. It can be useful if the need is to see the evolution of the DUT output signal spectrum in the function of the input power.
Multiple options are available to set the spectrum analyzer and optimize the measurement speed and accuracy.

 


 

1-Tone measurements using a scalar setup

IQS100B-10 enables a scalar characterization of the DUT using a signal generator and power meters.

Different sweep settings are available to the end-user allowing appropriate characterization of different power amplifier technologies. Following the calibration parameters of frequency bandwidth and power range, it is possible to execute sweeps in different acquisition modes.

The acquisition mode helps the user characterize the DUT in the right conditions to minimize the effects of technology-related phenomena (Thermal, Traps…). IQSTAR embeds four (4) different acquisition modes:

 

1-Tone measurements using a scalar setup 1

1-Tone measurements using a scalar setup 2

1-Tone measurements using a scalar setup 3

 


 

Measurement parameters

Operating and transducer gain compression modes are available to characterize a power amplifier, including compression from linear and compression from maximum gain.

GaN-based power amplifiers need more cautious characterization as the power sweeps always need to start from the same trapping level. For that, IQSTAR embeds a quiescent current stabilization option to monitor the current settling in the quiescent state over time and ensures it reaches the right level before triggering a new power sweep.

Measurement speed is an important factor when characterizing Power Amplifiers. Most of the measurement time is spent in instrument triggering and data transfer to the computer. Therefore, IQSTAR embeds a DC Measurement selection capability that lets the user choose the critical DC parameters that need to be measured continuously from the instruments (ex: Output Currents) and the less critical parameters that do not vary during the measurements for which he can just keep the initial set value.

An extensive list of predefined parameters is measured and available during the live visualization depending on the setup configuration. In addition, user-defined parameters can also be added to the predefined list. The user can consult the results using the visualization tool in real-time during the measurements. Besides the history measurements available for display, it is also possible to set some specifications limits that the circuit under test needs to reach. A colour-coded display allows a fast evaluation of the DUT and indicates if it passes or fails.

Measurement Parameters

 


 

DUT Protection

The protection of the test bench and the measured circuits are top priorities for RF power characterization. Therefore, multiple stop conditions can be set in the software: Gain compression, Maximum output power, efficiency compression, Input Gamma and more.

IQSTAR embeds a Robust optimization algorithm of the input power level at the DUT reference plans to allow complete control independently of the RF source, driver amplifier drift, or bias voltage drop.

 

DUT Protection

 


 

Sweep Plan

Automated measurement is an easy task with IQSTAR. Sequencing measurements with minimum human intervention is key to optimal testing efficiency. One person can run multiple benches simultaneously to speed up testing capabilities. Through drag and drop actions, it is possible to define several tasks to be performed and run the complete measurement scenario automatically. The “Sweep Plan” takes advantage of all GUI tools already available in the bench definition interface or from the measurement interface. This way, defining a complete measurement task is possible without programming skills and any loss of flexibility.

IQSTAR automation capabilities using the “Sweep Plan” allow:

  • Single setup and multi-setup configurations
  • Measurement sequencing with loop and stop conditions.
  • Nested measurements sweep
  • DUT bias control & optimization
  • Probe station control
  • Chuck temperature control
  • SCPI commands for specific instrument control during the automation
  • Possibility to save sweep plans with all parameters for future use

 

The Vector Bench module IQS100B-11 includes all the capabilities described in the IQS100B-10 module, with the addition of vector measurements using a Vector Network Analyzer (VNA). With such a setup, the amplitude and phase information can be captured using the receivers of the VNA. When both measurement possibilities are enabled in the setup ( Scalar and Vectorial), choosing which instruments to use for the characterization is possible by selecting the corresponding calibration.

The module IQS100B-10 is a prerequisite to the module IQS100B-11.

 


 

Calibration

IQSTAR provides corrected data at the DUT reference plane. The correction terms are calculated during the calibration process using a step-by-step wizard. Depending on the setup configuration, different calibrations can be performed. The Vector Network Analyzer (VNA) calibration is necessary for vector setups to extract the error terms.

Calibration IQS100B-11

Furthermore, the vector calibration and power calibration can differ depending on the VNA configuration, which can be set to use three (3) or four (4) receivers. Therefore, and to minimize the source of errors, IQSTAR provides a state-of-the-art calibration wizard that relies on the schematic setup to identify the type of calibration possible to perform and guides the end-user through all the steps, including the validation process verifying and assessing the expected accuracy.

 


 

S-Parameters

Perform a frequency sweep on the VNA, and display the corrected S-parameters at the DUT reference plane using the live visualization tool.
Device tuning becomes easier with trace history as up to fifty (50) iterations and measurements can be displayed on the same graph. Import S2P simulation files and compare them with measurements in different display formats.
With Probe station control, measure multiple devices with one click. IQSTAR supports major automatic probe station vendors and remotely controls the wafer movement. Adding the bias conditions to the sweep plan, one can generate a large amount of data with minimum interaction with the instruments.

S-Parameters

 


 

1-Tone measurements using a vector setup

1-Tone measurements with IQS100B-11 module include all the capabilities of IQS100B-10 regarding the sweep settings, the acquisition modes, stop conditions for DUT protection and visualization, with some additional features.

Acquisition Modes

Additional to the acquisition modes available in a scalar setup, the Fast CW mode is enabled with a vector setup

1-Tone Measurement using a vector setup

 


 

Measurement parameters

In addition to the measurement parameters obtained in a Scalar mode, the vector mode enables phase measurements to extract input Gamma of the DUT and AM-PM conversion.

IQS100B-20 is an Add-On to the module IQS100B-10.

IMD Control, 2-Tone Measurements

IQSTAR allows multiple configurations to measure intermodulation distortion (IMD) with a 2-Tone signal.

Using two combined analog RF sources or one vector signal generator, a spectrum analyzer, or a vector network analyzer, IQSTAR guides you through a simplified calibration procedure and provides high measurement accuracy.

 

IMD Control, 2-Tone Measurement

When a scalar setup is used, the software can control the spectrum analyzer to measure the power of each component of the spectrum at the output of the DUT and extract intermodulation distortion up to the ninth order and intercept points. This configuration requires the IQS100B-10 module.

 

Using the VNA, IQSTAR takes advantage of the dynamic range of the receivers and measures the a-and b-waves to extract the intermodulation product signals and the two carrier tones to calculate the IMD up to the ninth level. The “Frequency Offset” option is required in the VNA for these measurements. As for the generators, IQSTAR handles sources from the VNA, independent sources, or a combination of both and optimizes the tones balance levels for an accurate IMD characterization. This configuration requires the IQS100B-10 and IQS100B-11 modules. A 3D nested sweep, including the carrier frequency, the power, and the spacing of the tones, can be performed to extract a complete IMD characterization of the Power Amplifier in one step.

VBW measurements represent a challenging measurement task. However, IQSTAR handles this measurement efficiently, setting the amplitude of the tones according to the target third-order intermodulation distortion (IMD3) value set by the user. Then, the software sweeps the spacing between the tones and adjusts the balance between them before recording the intermodulation—up to the ninth order. Taking advantage of the speed of VNA sweeps, this measurement takes just a few minutes.

 

The IQS100B-22 module is an add-on to the IQS100B-11 to add an electro-mechanical impedance tuner to the setup and perform measurements under VSWR variation. This option is only supported for a Vector Bench setup. A basic two-dimensional (2D) sweep is by default available in IQSTAR, where the user can enter a list of frequencies and power levels. In release 1.3, the VSWR sweep is added with the module IQS100B-22, allowing three-dimensional (3D) nested loops sweep.

 


 

Constant VSWR Control

Controlling a load impedance tuner, the user can generate an impedance pattern in the shape of constant VSWR circles with different magnitudes and phase steps.
This functionality ensures that the power amplifier under test delivers the expected performances for different powers, frequencies, and load impedances.
IQSTAR enables a smooth combination of these different test conditions to launch measurements on the fly through a seamless control of Maury Microwave tuners.

 

This module is an Add-on to the IQS100B-10, enabling spurious analysis. This module is compatible with both Scalar and Vector Bench Control modules. If a Vector bench is used, the IQS100B-11 module is a prerequisite.

 


 

Fast Spurious Detection

Starting with IQSTAR 1.3 release, Fast Spurious detection is available. This module allows a fast search and analysis of spurious signals, using the spectrum analyzer to recover the trace for each swept parameter. A processing algorithm is then employed to dissociate spurious frequencies from signal frequencies. Detection-per-frequency segment is possible when different criteria based are needed for each band.

Spurious detection is an important step in the Design Validation Testing (DVT) and the Production validation testing (PVT) of RF and Microwave power amplifiers. Spurious emissions decrease the system performance and cause interference in adjacent frequency bands. Some industries like aerospace and defense must detect very low-level spurs.

A classical technique consists of reducing the resolution bandwidth to the narrowest to lower the noise floor of the equipment. However, the implementation simplicity of this technique comes at the cost of a very long measurement time, especially since the spurious location cannot be predicted in advance, which imposes a full scan of a large frequency bandwidth at a very low RBW level.

Even with new fast spectrum analyzers, spurious detection can take hours or even days when combined with nested loops of frequencies, biases, power levels, VSWR circles…

 

IQSTAR takes advantage of fast spectrum analyzers using FFT filters to search spurs and reduce testing time. The spurious research algorithm embedded in IQSTAR automates and speeds up the process. A simple GUI is used to identify the frequency segments for the spurious detection with different noise levels, spurious threshold levels, number of points and more settings. The software optimizes the RBW level automatically to find the best trade-off between the detection threshold and the measurement speed.

 

In other words, the RBW is set to the lowest level to detect real spurs at required frequencies and higher in the ranges where no potential spurs have been detected. Spurs generated by the analyzer itself, called residuals, are identified and automatically removed from the result list.

 

This module is an Add-On to the IQS100B-10.

Modulated Signal Control and Measurements

 

The DUT can be characterized using a complex RF signal, and different figure-of-merit related to a modulated signal excitation can be extracted. The growing complexity of wireless systems imposes a thorough and detailed characterization of RF power amplifiers using wideband signals. IQSTAR enables high-speed and signals quality measurements to evaluate DUT performances (EVM, ACPR, CCDF, PAPR…).

With full control of the vector signal generator, it is possible to set the modulation scheme manually with adequate settings and have IQSTAR recall the required state on the instrument. Otherwise, it is possible to generate an IQ waveform using IQSTAR Waveform Generator or any third-party software and use it directly in IQSTAR by loading a text file containing the columns “I” and “Q”.

The Signal analyzer, with appropriate options and power meters, are used to measure different parameters like:

  • Adjacent Channel Power Ratio (ACPR)
  • Error Vector Magnitude (EVM)
  • Complementary-Cumulative-Distribution-Function (CCDF)
  • Peak-to-Average Power Ratio (PAPR)
  • Spectrum

 


IQSTAR Modulation measurements support multiple combinations of vector signal generators and signal analyzers from different vendors, allowing the test engineers to switch between instruments seamlessly and reduce the cost of ownership as he does not have to learn a new instrument user interface.

 

This Module is an Add-on to IQS100B-10.

IQ Data Control and Measurements

 

IQSTAR uses IQ values sent to the Vector Signal Generator (VSG) and fetched from the Vector Signal Analyzer (VSA). The IQ data is resized, realigned, and analyzed in IQSTAR to extract user-selected parameters (ACPR, CCDF, PAPR, Dynamic AM-AM…). With this option, the VSA does not need to have any software options as IQSTAR makes sure to align the IQ signals at the input and the output and extract all requested parameters.

The Available Measurements are:

  • IQ Data
  • EVM on Symbol
  • ACPR
  • CCDF with Trace
  • Dynamic AM/AM and AM/PM
  • Instrument-based DPD

 

With the IQ Module, no software options (excluding DPD) are required in the instruments to analyze the signal, making it a scalable solution with minimum hardware updates. The setup is only limited by the instantaneous bandwidth of the signal generator and the signal analyzer. IQSTAR embeds an IQ Measurement Interval selection tool to speed up the measurement process, identifying the most appropriate signal segment that best represents the original one in terms of statistical characteristics. This feature is very useful when a trade-off between measurement speed and accuracy is required. When instruments are equipped with DPD analysis options, IQ Module can control these options. It uses appropriate instrument drivers and enhances the power amplifier characterization by verifying its linearizability.

 

This module is an Add-Onto the IQS100B-40 module to apply different DPD techniques.

DPD Module

Power Amplifiers are the most critical components in a communication system and are inherently nonlinear. The nonlinearity generates spectral regrowth, which leads to adjacent channel interference and violations of the out-of-band emission requirements. The nonlinearity also causes in-band distortion degrading the performance of the bit error rate (BER). It is possible to reduce the nonlinearity by backing off the power amplifier to work in the linear region. Still, this method is not viable because of the low efficiency of the power amplifier in this regime. Power amplifiers must be linearized using different techniques to enhance efficiency without compromising the linearity. IQSTAR 1.2 introduced several DPD techniques and algorithms to verify that the Power amplifier under test can be linearized with more or less complexity.

 

When different DPD techniques must be tested on the Power amplifier, the software must make more than one algorithm available. Starting version 1.2 of IQSTAR, a dedicated DPD module was released to respond to this request:

  • Sample-based
    • This technique is an iterative measurement-based method that allows achieving quasi-ideal linearization results for reference purposes. Indeed, this method is used during the verification and development phase of the PA and cannot be implemented as a real-time DPD algorithm in a transmitter.
  • Memoryless (M)
    • Memoryless models focus on the power amplifier with a memoryless nonlinearity: the current output depends only on the current input through a nonlinear mechanism. This instantaneous nonlinearity is usually characterized by the power amplifier's AM/AM and AM/PM responses. The output signal amplitude and phase deviation of the power amplifier output are given as functions of the amplitude of its current input.
  • Memory Polynomial (MP)
    • The memory model is commonly used as the signal bandwidth gets wider and the power amplifiers exhibit memory effects, especially for high-power amplifiers used in wireless base stations. Consequently, the current output of the power amplifier depends on the current input and the past input values.
  • Generalized Memory Polynomial (GMP)
    • This model is built by augmenting the memory polynomial model taking into account the cross-term order. The user can set this order.
  • Nanosemi Single-band Algorithm (DLL to be acquired by the customer)
    • This option controls the Nanosemi single-band algorithm through a DLL and applies it externally to the measurements using instruments from different vendors. The Nanosemi DLL must be acquired separately.
  • Nanosemi Dual-Band Algorithm (DLL to be acquired by the customer)
    • This option controls the Nanosemi dual-band algorithm through a DLL and applies it externally to the measurements using instruments from different vendors. The Nanosemi DLL must be acquired separately.
  • Matlab-based customer-developed DPD algorithm
    • This option is a gateway to run a Matlab-based DPD algorithm developed by the user. This option also offers an Open-source MP algorithm that the user can adjust and optimize to his power amplifier under test. Matlab license must be acquired separately.

 

SCRPT is an add-on module to IQS100-B10/B11/B20/B30/B40, enabling advanced measurement sequencing using a dedicated scripting language and running applications from third-party software. SCRPT enables only the functions related to the IQS100B module available in the software license.

 


 

SCRPT
Scripting Add-On

Scripting is available internally to IQSTAR through a dedicated editor. Starting Rev 1.3, Scripting is also available via an external script server and controlled in slave mode by a third-party application or software.

Multiple functions are included in the script editor and divided into different categories:

  • Measurements System: these functions allow full automation of the measurement process, including the setup creation, the measurement configurations, the device biasing, the biasing optimization, the wafer mapping and many more.
  • User Interface: these functions are related to creating 2D and 3D graphs, dialogue boxes, and different utilities.
  • Math functions: an extensive mathematical library is available to compute necessary parameters. These functions include array manipulations like SVD and LU operations, polynomial modeling and curve fittings and many more functions.
  • Native: This category of functions is very useful when dealing with external DLL that must be controlled during the measurements.
  • Net Visa: Dedicated Visa-based instruments control is allowed directly from the script to integrate additional instruments to the bench like thermal chambers, for example.

 

This module is a standalone yearly subscription-based software. It helps generate different waveforms used in modulated or IQ signal modules.

Advanced Waveform Generator

IQSTAR embeds a basic waveform generator that can create different PSK and QAM signals and inject them directly into the signal generator. Starting with IQSTAR release 1.3, an Advanced Waveform Generator is available. AS this module is standalone, it can be used independently from IQSTAR. The different waveforms can be used for different modulation schemes:

  • PSK & QAM
  • Custom OFDM
  • LTE Downlink FDD/TDD
  • Multi-Carrier Signal
  • Crest Factor Reduction


The waveform can automatically be used to generate the signal sent to the Vector Signal Generator or be exported to a *.txt file to be used with a third-party application.

Visualization
Visualization Tool

IQSTAR is provided with a visualization tool for each measurement module. Different displays are made available, allowing single or multiple graphs. Depending on the performed measurements, an extensive list of graph types is predefined, including

  • XY Graphs
  • Smith Charts
  • Polar
  • Tables
  • Spectrum
  • CCDF traces
  • EVM constellation
  • ACPR Mask
  • And many others

Different controls and filters allowing the display of different parameters at a specific frequency, power, or VSWR level make the performance evaluation of the device easier to analyze. User-defined templates can be saved and recalled. Measurement data can be exported to standard formats like CSV and MDIF. 

 

IQSTAR Configuration Information

This Whiteboard module allows the user to create and customize as many graphics as necessary and position them into a user-defined template to visualize measurement results. It is possible to incorporate texts and images to create an interactive measurement report. An interactive display, including tables and graphics, can be generated using different filters or sliders.

 


 

WHIT-01
WHITEBOARD EDITOR BUNDLE

IQSTAR & WHITEBOARD Editor Bundle allows the visualization of as much data as possible without compromising flexibility. Circuit or system designers generally wish to import measurement or simulation data into a suitable environment to verify their design and/or verify the agreement between simulated results, measured performances, and reference data. If they don't have dedicated tools, they use homemade ones, which are generally costly in development time, workforce, and maintenance.

The data can be analyzed in a raw format or be processed via an equation editor, allowing to customize the analysis. By customizing his analysis environment, with a few clicks, the user can reload new measurement or simulation data in a predefined analysis environment.

This tool is essential for the in-depth analysis of RF systems simulations results. The simulated quantities, the variables used, and the size of the data can be parameterized at any time.



Videos

RF power amplifier measurement using COTS RF transceiver with IQSTAR / EUMW 2021 London
IQSTAR 1.3 Ruggedness PA test
IQSTAR 1.3 Fast Spurious detection
IQSTAR 1.3 RF Waveform Generator
IQSTAR 1.1 Release 2020
IQSTAR Wideband DPD at NI-Week 2019
IQSTAR AMCAD Live Demo with Copper Moutain VNA at IMS 2019
IQSTAR AMCAD Live Demo at IMS 2018