- ProductsProductsPI Ceramic offers a large number of standard products and solutions based on piezo technology. This includes piezoceramic components and elements as well as piezoelectric actuators.
- Piezoceramic ComponentsPiezoceramic ComponentsPI Ceramic manufactures a wide range of piezoceramic components in various shapes and sizes according to your needs – also with contacting or in miniature format.
- Piezoceramic ActuatorsPiezoceramic ActuatorsPI Ceramic offers a large number of piezoelectric actuators for applications in industry and research.
- PICMA® Piezo Linear ActuatorsPICMA® Piezo Linear ActuatorsThe compact PICMA® multilayer actuators feature linear deflections with low control voltages and, in the chip version, generate highly dynamic movements.
- PICMA® Piezo Bender ActuatorsPICMA® Piezo Bender ActuatorsMultilayer bending actuators: large displacement and high dynamics. Their bimorph structure ensures bidirectional displacement.
- PICA Piezoelectric Stack ActuatorsPICA Piezoelectric Stack ActuatorsStacked piezo linear actuators with operating voltages to 1000 V: High reliability, large specific displacement and high forces.
- PICA Shear ActuatorsPICA Shear ActuatorsMulti-axis and shear actuators in stacked design offer excellent dynamics combined with minimum electrical power requirements.
- DuraAct Patch TransducersDuraAct Patch TransducersDuraAct patch transducers convert electrical voltage into mechanical energy and vice versa; as actuator, sensor or as energy generator.
- Picoactuator® Piezoelectric CrystalPicoactuator® Piezoelectric CrystalThe motion of the Picoactuator® piezo crystals is highly linear and almost hysteresis-free and consequently suited for high-dynamics applications.
- Tube ActuatorsPiezo Tube ActuatorsRadially and axially contracting piezo tubes are often used for creating dynamic scanning motions and as fiber stretchers.
- PICMA® Piezo Linear Actuators
- Smart Interface: Piezo Components with Flexible Printed Circuit BoardsSmart Interface: Piezo Components with Flexible Printed Circuit BoardsIt is time-consuming and risky to provide piezo components with strands and to contact them on printed circuit boards yourself. PI Ceramic takes on this step for customers and supplies piezoceramic components with flexible printed circuit boards.
- Piezo Controllers & DriversPiezo Controllers & DriversControl electronics plays a key role in the performance of piezoelectric actuators. In addition to universal control electronics, highly suitable for most fields of application, PI offers a wide range of piezo amplifiers geared towards particular purposes.
- For PICMA® Stack/Chip Multilayer ActuatorsDrivers and Controllers for PICMA® Stack/Chip Multilayer ActuatorsAmplifiers with high output current allow dynamic operation of the actuators and precise positioning while requiring low power.
- For PICMA® Bender Multilayer ActuatorsDrivers and Controllers for PICMA® Bender Multilayer ActuatorsPiezo amplifiers for PICMA® Bender Actuators offer fixed and variable output voltages of up to 60 V for differential control.
- For PICA Stack/Power/Thru ActuatorsDrivers and Controllers for PICA Stack/Power/Thru ActuatorsPiezo amplifiers for PICA Actuators offer a voltage range of up to 1100 V, which is available as unipolar or bipolar voltage. Amplifiers with high output current allow dynamic operation of the actuators and precise positioning while requiring low power.
- For PICA Shear ActuatorsDrivers and Controllers for PICA Shear ActuatorsPiezo amplifiers for PICA Shear Actuators offer a bipolar output voltage of ±250 V.
- For DuraAct ActuatorsDrivers and Controllers for DuraAct ActuatorsDuraAct Actuators require different operating voltage ranges, depending on the integrated ceramic.
- For Picoactuator® ActuatorsDrivers and Controllers for Picoactuator® ActuatorsPicoactuator® actuators are operated with a bipolar voltage of ±500 V. The output voltage range of the PICA amplifiers can be set accordingly to suit this purpose. For smaller displacements, it is possible to use amplifiers for PICA Shear actuators of ±250 V.
- For Piezo TubesAmplifiers and Controllers for Piezo TubesPiezo amplifiers for Piezo Tubes are ideal for the control of segmented piezo scanner tubes and can be operated with a bipolar voltage.
- For Energy HarvestingElectronics for Energy HarvestingE-821 uses pulsed or continuous excitation for Energy Generation by means of piezo actuators.
- For PICMA® Stack/Chip Multilayer Actuators
- Piezoceramic MaterialsPiezoceramic MaterialsPI Ceramic offers a variety of different piezoelectric materials including lead-free materials.
- Miniaturized Piezo CeramicsMiniaturized Piezo CeramicsThanks to their compact design, miniaturized piezo components are ideally suited for the generation and detection of vibrations in the smallest of areas.
- DisksMiniaturized Disks
- PlatesMiniaturized Plates
- RingsMiniaturized Rings
- TubesMiniaturized Tubes
- Half and Hollow SpheresMiniaturized Half and Hollow Spheres
- Shear ElementsMiniaturized Shear Elements
- Bending ElementsMiniaturized Bending Elements
- HexagonsMiniaturized Hexagons
- (Shear) ConesMiniaturized (Shear) Cones
- Chip Actuators (PL022.3x)Chip Actuators (PL022.3x)
- Piezoceramic Components
- OEMOEM Solutions for Piezo Ceramics from PI CeramicPI Ceramic offers customized OEM solutions for piezo ceramics at the highest technological level and economically optimized.
- The PI Ceramic Tech CenterThe PI Ceramic Tech CenterFrom small series production to new production technologies: the PI Ceramic Tech Center supports you in the fast qualification of your project-specific samples.
- The PI Ceramic Tech Center
- ApplicationsApplications and Markets for Piezo TechnologyPiezo technology is used in different applications in medical technology, mechanical and automotive engineering or in semiconductor technology.
- Ultrasonic Measurement TechnologyUltrasonic Measurement TechnologyUltrasonic sensors emit high-frequency sound pulses and receive signals reflected from objects. The time the echo signals take to arrive is processed electronically and can be used for a wide range of applications in metrology.
- Noncontact Measurement with Air UltrasoundNoncontact Measurement with Air UltrasoundThe most widely used principle of ultrasonic level measurement is based on the propagation time measurement of air ultrasound pulse.
- Noncontact Flow MeteringNoncontact Flow MeteringThe propagation time metering the so-called Doppler principle are the two fundamental measurement processes in noncontact ultrasonic flow rate measurement.
- Noncontact Measurement with Air Ultrasound
- High-Power UltrasoundHigh-Power UltrasoundPiezoceramics can be used to generate ultrasonic waves in the frequency range of power ultrasound (20 to 800 kHz). They can be used in different diagnostic and therapeutic applications, for example in tartar removal or lithotripsy, but also in ultrasonic technology.
- Industrial Ultrasonic CleaningIndustrial Ultrasonic CleaningUltrasonic cleaning can be used to remove dirt particles in the nanometer range, without damaging sensitive surfaces by a too high pressure.
- Ultrasonic PiezomotorsUltrasonic PiezomotorsAn integral part of the PILine® ultrasonic piezomotors is a piezoceramic actuator that is pretensioned against a movably guided runner via a coupling element.
- Sonar Technology and HydroacousticsSonar Technology and HydroacousticsPiezoceramic components are used in sonar technology and hydroacoustic systems, for measuring and position-finding tasks.
- Industrial Ultrasonic Cleaning
- Acceleration MeasurementAcceleration MeasurementPiezo discs the centerpiece of force/acceleration sensors.
- Scientific InstrumentationScientific InstrumentationPiezo components have become firmly established in modern science as drives and ultrasonic transducers. They work reliably even under extreme conditions such as magnetic fields, cryogenic temperatures or ultrahigh vacuum.
- Mineralogical Analyses in NASA's Mars RoverMineralogical Analyses in NASA's Mars RoverNASA relies on PICMA® Multilayer Actuators from PI Ceramic.
- Cryogenic Applications in the German Electron Synchrotron (DESY)Cryogenic Applications in the German Electron Synchrotron (DESY)Dynamic Compensation of Lorentz Forces at the Accelerator Elements in Cryogenic Environments.
- Scanning Probe MicroscopyScanning Probe MicroscopyScanning probe microscopy benefits from piezo technology: Piezo tube actuators position highly dynamically over a lateral range of up to ±35 µm.
- Mineralogical Analyses in NASA's Mars Rover
- Precision DosingPrecision DosingPiezo elements pump and meter small liquid or gas volumes reliably and precisely in the range of a few hundred milliliters to a few nanoliters. The piezo elements can be adapted to each application environment.
- Metering with Piezo ValvesMetering with Piezo ValvesPiezo valves are highly suitable for dosing tasks: They can switch directly, and can also work against a closing spring.
- Metering with Piezo Valves
- Medical TechnologyMedical TechnologyPiezo components for medical technology and related life science disciplines must be fast, reliable and energy-efficient. In miniaturized form, they enable minimally invasive and highly precise diagnostic as well as therapeutic methods.
- Therapeutic Ultrasound with Piezo ComponentsTherapeutic Ultrasound with Piezo ComponentsTherapeutic ultrasound is used as a core element in applications such as tissue ablation, targeted drug delivery, or lithotripsy.
- Miniaturized Piezo Tubes in SFEMiniaturized Piezo Tubes in High-Resolution Scanning Fiber EndoscopyWith their fast deflection and control, miniaturized piezo tubes generate a scanning movement of the optical fiber in scanning fiber endoscopes (SFE), thus providing more image information and improved minimally invasive procedures in everyday clinical practice.
- Nebulizers with Piezo RingsNebulizers with Piezo RingsSpecially shaped piezo discs act as ultrasonic transducers in nebulizers, generating particularly homogeneous aerosols with high-frequency oscillations.
- Piezo Valves in BiotechnologyPiezo Valves in BiotechnologyPiezo-driven valves enable precise dosing in the nanolitre range, for example for drug screening or researching active agents.
- Piezoelectric MicropumpsPiezoelectric MicropumpsPiezoelectric micropumps are used in laboratory technology, medical technology, biotechnology, chemical analytics and process engineering.
- Piezo Actuators in Medical ImplantsPiezo Actuators in Medical ImplantsSystems implanted in the body such as micropumps for drug dosing or hearing aids are almost invisible and improve the quality of life of patients significantly. They are driven by ultra-compact and energy-efficient miniaturized piezo actuators.
- Therapeutic Ultrasound with Piezo Components
- Energy-Autarkic SystemsEnergy-Autarkic Systems with Piezo ElementsDuraAct patch transducers use kinetic energy for the electrical supply of energy-autarkic systems and can be applied in structural health or condition monitoring.
- Ultrasonic Measurement Technology
- TechnologyPI Ceramic Piezo TechnologyPI Ceramic offers extensive know-how and a wealth of experience in the manufacturing of assembled piezo-ceramic components and sub-systems.
- Fundamentals of Piezo TechnologyFundamentals of Piezo TechnologyPhysical basics and explanations of piezo electricity and electromechanics.
- Properties of Piezo ActuatorsProperties of Piezo ActuatorsCharacteristics of piezoceramic actuators: Displacement modes, forces and stiffnesses, dynamics. Ambient conditions.
- Displacement BehaviorDisplacement BehaviorOn this site you will find information about the displacement behaviour of piezo ceramics.
- Displacement Modes of Piezoelectric ActuatorsDisplacement Modes of Piezoelectric ActuatorsOn this site you will learn more about the different displacement modes of piezo ceramics.
- Temperature DependenceTemperature DependenceThe displacement and dimension of a piezo ceramic is temperature dependant. Learn more about this topic on this site.
- Forces and StiffnessForces and StiffnessForce and stiffness are important properties of piezo actuators. Find out more on this topic here.
- Dynamic OperationDynamic OperationLearn more on the topics of resonant frequency, dynamic forces and response behaviour.
- Electrical Operation of Piezo ActuatorsElectrical Operation of Piezo ActuatorsLearn more on the topics of operating voltage, electrical behaviour and operating modes.
- Ambient ConditionsAmbient ConditionsPiezo actuators are suitable for operation in very different, sometimes extreme ambient conditions. Learn more about this topic on this site.
- Displacement Behavior
- Generating UltrasoundGenerating Ultrasound with Piezo ComponentsPiezo components use the piezoelectric effect to generate and detect ultrasonic waves, e.g. by means of runtime measuring or the principle of the Doppler effect.
- Developing Customized TransducersDeveloping Customized TransducersIn addition to piezo components, PI Ceramic also supplies complete transducers, which are developed together with you according to your application specifications.
- Developing Customized Transducers
- Manufacturing TechnologyManufacturing TechnologyPI Ceramic offers a wide range of manufacturing technologies: Pressing or tape technology, assembling technology and testing procedures.
- PICMA® TechnologyPICMA® TechnologyHighly reliable and extended lifetime through the patented manufacturing process for multilayer actuators.
- DuraAct Patch Transducer TechnologyDuraAct Patch Transducer TechnologyManufacture, functional principle and typical working parameters of DuraAct patch transducers explain the possible force generation and deflection.
- Fundamentals of Piezo Technology
- ServiceServiceIn the service area you can contact us, search and download documents and use our technical glossary.
- DownloadsDownloadsIn the download section you will find product documentation, broschures, sucess stories and whitepapers.
- Product DocumentationProduct DocumentationDownload user manuals, technical notes or datasheets.
- Catalogs, Brochures & CertificatesCatalogs, Brochures & CertificatesDownload the newest PDF files or request printed catalogs and brochures by mail.
- Whitepapers & Success StoriesWhitepapers & Success StoriesDownload whitepapers and success stories and learn more about our products.
- Product Documentation
- Ask an Engineer!Ask an Engineer!Quickly receive an answer to your question by email or phone from a local PI Ceramic sales engineer.
- PI Glossary for Technical TermsPI Glossary for Technical TermsIn the glossary you will find explanations of the different terms used on the website.
- News & EventsNews & EventsHere you can find current information on PI Ceramic and also upcoming events and trade fairs.
- NewsNews & PressLatest news on PI Ceramic: Browse our news archive.
- Trade Fairs & EventsTrade Fairs & EventsTake the opportunity to meet PI Ceramic at trade fairs and events.
- Virtual Trade Show StandsWelcome to Our Virtual Trade Show Stands!We would be pleased to welcome you personally at our exhibition stands all over the world. In addition, we also invite you to our virtual trade show stands - be inspired by our application solutions!
- Virtual Trade Show Stands
- About PI CeramicCompany PI Ceramic GmbHPI Ceramic, a subsidiary of Physik Instrumente (PI) GmbH & Co. KG, is located in the city of Lederhose, Thuringia, Germany.
- How to Get to PI Ceramic!How to Get to PI Ceramic!Here you will find adress data and directions to PI Ceramic.
- About PI GroupAbout PI GroupNo other company in the world offers a broader and deeper portfolio of precision motion technologies than the PI Group. Continuous growth through the development of novel products and technologies is one of the main characteristics of the PI Group.
- ReferencesReferencesOn this site you will find external publications from industry and research.
- Legal InformationLegal InformationOn this site you will find legal Information about PI Ceramic
- How to Get to PI Ceramic!
- CareersCareersWe like and look for people who share the same vision and dynamics we do. People who want to make a difference and have ambitious objectives. Let's shape the future together!
- Careers at PICareers at PIIf you come on board as a new employee, we can tell you now and promise: Your future at PI will be varied. Dynamic. Exciting in a good way. Challenging. Full of opportunities. Promising and multifaceted. Productive and innovative. Are you ready to come on board at PI and ready to think about the future together and turn it into reality?
- Jobs at PI CeramicJobs at PI CeramicDo you want to take the next step into your professional future? If so, you should take a good look at the job vacancies in our job overview.
- KarlsruheKarlsruhePI is the future. We make it possible for our customers to master technological leaps and shape trends for decades to come. Become part of an agile medium-sized company with global power.
- Our BenefitsBenefitsYou give a lot. We do everything! We are very much aware that our most important capital is not in the bank: Our employees are the very foundation of our success.
- Experienced & Young ProfessionalsExperienced & Young ProfessionalsOff on new missions! Let us find a new vision. And turn it boldly into reality. Join us and be curious to discover new things, dare to be courageous, and break new ground. For you. For our company. And for everybody who will benefit from our technological innovation.
- StudentsStudentsAt PI, you have the opportunity to get to know the professional world in an exciting and modern working environment. As a student, you can do an internship in all departments, get your first practical work experience as a student worker or successfully complete your studies with a practice-oriented bachelor or master thesis.
- Trainees & Dual Curriculum StudentsTrainees & Dual Curriculum StudentsOur future lies in training the professionals of tomorrow. And: You could be that professional! If you want to start your professional career with motivation and commitment, you've come to the right place!
- Our Benefits
- LederhoseLederhosePI Ceramic in Lederhose in Thuringia develops and manufactures high-tech solutions in the field of piezo technology. Become part of an agile medium-sized company with global power that continues to grow consistently and sustainably at Lederhose and offers attractive prospects.
- Our BenefitsBenefits
- Experienced & Young ProfessionalsExperienced & Young ProfessionalsOff on new missions! Let us find a new vision and turn it boldly into reality. Join us and be curious to discover new things, dare to be courageous, and break new ground. For you yourself. For our company. And for everybody who will benefit from our technological innovation.
- StudentsStudentsAt PI Ceramic, you have the opportunity to get to know the professional world in an exciting and modern working environment. As a student, you can do an internship in almost all departments of the company, take an internship semester or you can complete your studies successfully with a practice-oriented bachelor or master thesis.
- Trainees & Dual Curriculum StudentsTrainees & Dual Curriculum StudentsYour future is also our future! Because we can shape and form the future together with high-tech and your training as a true professional. Therefore, at PI Ceramic, we have therefore been training specialists for technical and commercial professions for many years and are happy to take on qualified junior staff in permanent employment.
- Our Benefits
- EschbachEschbachWe at PI miCos are redefining high-tech both internationally and globally. Our mission: Technology highlights all over the world, made in Eschbach. Benchmark from Breisgau. Wouldn't that be something for you too?
- Our BenefitsBenefits
- Experienced & Young ProfessionalsExperienced & Young ProfessionalsHave you have just graduated or do you have professional experience already. Are you ready for the next step in your career? Then PI miCos is the right partner for you! We are future-oriented and international and therefore offer you a secure job with exciting tasks and interesting prospects.
- StudentsStudentsYou have the opportunity at PI miCos to familiarize yourself with the professional world as a student in an exciting and modern working environment - and to complete your studies successfully with a practice-based bachelor thesis or master thesis.
- Trainees & Student InternshipsTrainees & Student InternshipsYour future is also our future! We can shape and form the future together with high-tech and your training as a true professional. This is why we will be training specialists as mechatronics engineers at PI miCos from 2021. If technology fascinates you, if you really want to make a difference and set out on your professional mission with exciting high-tech, then you've come to the right place!
- Our Benefits
- Careers at PI
- BlogBlogFind news on products, technologies and applications, and information on trade fairs and other events.
- PI StorePI StoreBuy piezo actuators and piezoceramic components online: The PI Store is available 24/7 and offers prices as well as delivery times without having to log in.
- 0Quote list
PI Ceramic offers various types of piezo actuators with different layer thicknesses. This results in nominal operating voltages of 60 V for PICMA® bender actuators and up to 1000 V for PICA actuators.
At operating frequencies well below the resonant frequency, a piezo actuator behaves like a capacitor. The actuator displacement is proportional to the stored electrical charge, as a first order estimate. The capacitance of the actuator depends on the area and thickness of the ceramic as well as the material properties. In the case of actuators that are constructed of several ceramic layers electrically connected in parallel, the capacitance also depends on the number of layers. In the actuators there are leakage current losses in the μA range or below due to the high internal resistance.
Accordingly, a PICMA® stack actuator with a layer thickness of 60 µm has an approx. 70 times higher capacitance than a PICA stack actuator of the same volume and a layer thickness of 500 µm. The electric power consumption P of both types is roughly the same due to the relationship P ~ C V2 since the operating voltage changes proportionally to the layer thickness.
When electrically charged, the amount of energy stored in a piezo actuator is approximately E = 0.5 CV2 . Every change in the charge (and therefore in displacement) is connected with a charge transport that requires the following current I:
Slow position changes only require a low current. To hold the position, it is only necessary to compensate for the very low leakage currents, even in the case of very high loads. The power consumption is correspondingly low. Even when suddenly disconnected from the electrical source, the charged actuator will not make a sudden move. The discharge and thus the return to zero position will happen continuously and very slowly.
Operation with Position Control
In closed-loop operation, the maximum safe operating frequency is also limited by the phase and amplitude response of the system. Rule of thumb: The higher the resonant frequency of the mechanical system, the higher the control bandwidth can be set. The sensor bandwidth and performance of the controller (digital or analog, filter and controller type, bandwidth) also limit the operating bandwidth of the positioning system.
Heat Generation in a Piezo Element in Dynamic Operation
Since piezo actuators behave like capacitive loads, their charge and discharge currents increase with the operating frequency. The thermal active power P generated in the actuator can be estimated as follows:
For actuator piezo ceramics under small-signal conditions, the loss factor is on the order of 0.01 to 0.02. This means that up to 2 % of the electrical power flowing through the actuator is converted into heat. In the case of large-signal conditions, this can increase to considerably higher values (fig. 3). Therefore, the maximum operating frequency also depends on the permissible operating temperature. At high frequencies and voltage amplitudes, cooling measures may be necessary. For these applications, PI Ceramic also offers piezo actuators with integrated temperature sensors to monitor the ceramic temperature.
P Power converted into heat [W] tan δ Dielectric loss factor (ratio of effective to reactive power) f Operating frequency [Hz] C Actuator capacitance [F] Vpp Piezo voltage (peak-to-peak) [V] Epp Electric field strength (peak-to-peak) [kV/mm]
Dielectric Loss Factors
Fig. 3 shows the dielectric loss factors tan δ for different materials and control modes at room temperature and with quasistatic control. The conversion between voltage and field strength for specific actuators is done with the layer thicknesses. The actual loss factor in the component depends on further factors such as the mechanical preload, the temperature, the control frequency, and the amount of passive material.
Continuous Dynamic Operation
To be able to operate a piezo actuator at the desired dynamics, the piezo amplifier must meet certain minimal requirements. To asses these requirements, the relationship between amplifier output current, operating voltage of the piezo actuator, and operating frequency has to be considered.
Both the average current and the peak current of the amplifier are relevant for driving a piezo actuator with a symmetrical triangular waveform. The maximum operating frequency of an amplifier can be estimated as follows:
A secondary constraint that applies here is that the amplifier must be capable of delivering at least Imax = 2 Ia for the charging time, i.e. for half the period. If this is not feasible, an appropriately lower maximum operating frequency should be selected. For amplifiers which cannot deliver a higher peak current or not for a sufficient period of time, the following equation should be used for calculation instead:
The effective or average current Ia of the amplifier specified in the data sheets is the crucial parameter for continuous operation with a sine wave. Under the defined ambient conditions, the average current values are guaranteed without a time limit.
For sinusoidal single pulses that are delivered for a short time only, the following equation can be used:
The above equation calculates the required peak current for a half-wave. The amplifier must be capable of delivering this peak current for at least half a period. For repeated single pulses, the time average of the peak currents must not exceed the permitted average current.
Signal Shape and Bandwidth
In addition to estimating the power of the piezo amplifier, assessing the small-signal bandwidth is important with all signal shapes that deviate from the sinusoidal shape.
The less the harmonics of the control signal are transferred, the more the resulting shape returns to the shape of the dominant wave, i.e. the sinusoidal shape. The bandwidth should therefore be at least ten-fold higher than the basic frequency in order to prevent signal bias resulting from the nontransferred harmonics.
In practice, the limit of usable frequency portions to which the mechanical piezo system can respond is the mechanical resonant frequency. For this reason, the electrical control signal does not need to include clearly higher frequency portions.
The fastest displacement of a piezo actuator can occur in 1/3 of the period of its resonant frequency. Response times in the microsecond range and accelerations of more than 10,000 g are feasible, but require particularly high peak currents from the piezo amplifier. This makes fast switching applications such as injection valves, hydraulic valves, switching relays, optical switches, and adaptive optics possible.
For charging processes with constant current, the minimal rise time in pulse-mode operation can be determined using the following equation:
As before, the small-signal bandwidth of the amplifier is crucial. The rise time of the amplifier must be clearly shorter than the piezo response time in order not to have the amplifier limit the displacement. In practice, as a rule-of-thumb, the bandwidth of the amplifier should be two- to three-fold larger than the resonance frequency.
Advantages and Disadvantages of Position Control in Switching Applications
A closed-loop controller always operates in the linear control range of voltages and currents. Since the peak current is limited in time and is therefore nonlinear, it cannot be used for a stable selection of control parameters. As a result, position control limits the bandwidth and does not allow for pulse-mode operation as described.
In switching applications, it may not be possible to attain the necessary positional stability and linearity with position control. Linearization can be attained, e.g., by means of charge-controlled amplifiers or by numerical correction methods.
- PI Store