3rd Order Intermodulation Distortion Research Articles

Estimation of electrostatic, analogue, Linearity/RF figures-of-merit for GaN/SiC HEMT

An experimental examination of AlGaN/GaN/SiC HEMT multi-bias behaviour is presented in this paper to add to the enormous amount of device performance data in varied operating bias conditions. The study investigates various device parameters, including electrostatic performance, DC figures of merit, RF figures of merit and non-linear parameters under multi-bias conditions. The electrostatic performance is evaluated by analyzing the Ids-Vds transfer curves, ON-state and OFF-state currents, subthreshold slope and subthreshold swing. The output current, transconductance (gm), 2nd-and 3rd-order transconductance (gm2, and gm3) behaviour of the GaN device over multi-bias indicates a significant potential. The transconductance-reliant non-linear performance is assessed by analyzing voltage intercept points (VIP2 and VIP3), 3rd-order intercept point (IIP3), 1-dB compression point (1-dB CP), 3rd-order intermodulation distortion (IMD3), and total harmonic distortion (THD). In the case of RF parameters, the maximum ft and fmax values are 41 GHz and 125.7 GHz, respectively, and GBW up to 640 GHz was achieved. The relevant parameters, specifically the gain frequency product (GFP), transconductance frequency product (TFP), and the gain transconductance frequency product (GTFP), demonstrated remarkable results with maximum values of 683 GHz, 380.1 GHz/V, and 9827.7 GHz/V, respectively. These findings provide some valuable perceptions which would facilitate the fabrication of cutting-edge technologies for present and future applications.

Design and optimization of vertical nanowire tunnel FET with electrostatic doping

While dealing with the nanoscale regime, most devices make sacrifices in terms of performance. So to meet the performance requirements, Electrostatic doped Vertical Nanowire Tunnel Field Effect Transistor (E-VNWTFET) is proposed and analysed in this work. The dimensions of Electrostatic VNWTFET structure are scaled down and then the analog performance parameters transconductance gm, gm2 (2nd order), gm3 (3rd order) and linearity parameters 2nd order Voltage Interception Point VIP2, 3rd order Voltage Interception Point VIP3, 3rd order Input Interception Point IIP3 and 3rd order Intermodulation Distortion IMD3 are analysed. It is observed that electrostatic technique of doping is better than charge plasma (CP) technique; because in CP technique costly metals are required for doping. The analog performance parameters of E-VNWTFET are investigated and using device simulation the demonstrated characteristics are compared with CP-VNWTFET. After simulation, the device exhibits ON current ION of 3.5 μA μm−1 and OFF current IOFF of 6.6 × 10−18 A μm−1; which offers a significant ION/IOFF of 1011. The reported subthreshold swing and Drain-induced barrier lowering DIBL are approx. 9.7 mV/Decade and 37.8 mV/V respectively.

Improvement of linearity in intensity-modulated analog photonic link based on all-optical wave shaping

In this paper, a novel all-optical architecture for multi-order nonlinear distortions (NDs) suppression in the intensity-modulation direct-detection (IM-DD) analog photonic link (APL) is proposed. A systematic analysis of the relationship between the NDs and all optical sidebands (OSBs) is summarized. Numerical simulation results show that, by optimizing the amplitude and phase of OSB, the 3rd-order intermodulation distortion (IMD3) can be significantly suppressed. Consequently, the spurious-free dynamic range (SFDR) of 107.1 dBHz8/9 is obtained, which is improved by 16.17 dB compared with a single quadrature biased Mach–Zehnder modulator (MZM) used in APL.

Load-Modulation-Based IMD3 Cancellation for Millimeter-Wave Class-B CMOS Power Amplifiers Achieving EVM < 1.2%

This letter presents a novel load-modulation-based 3rd-order intermodulation distortion (IMD3) cancellation technique for class-B CMOS power amplifiers (PAs). In a class-B PA, the IMD3 generated by the 3rd-order transconductance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m3}$ </tex-math></inline-formula> ) and the gain compression have opposite signs, and thus, they can cancel each other at specific bias and loading conditions. The proposed Doherty topology allows adjusting the gain compression by modulating the effective loading, facilitating IMD3 cancellation over the entire load modulation region. The proposed approach is verified using a 28 GHz 40 nm CMOS series-Doherty PA (DPA) topology. The experimental result demonstrates 10/17 dB IMD3 improvement compared to class-B/DPA operation. Without using any digital pre-distortion, the measured EVM of the proposed technique for a 50 MHz 64-QAM OFDM signal with 8.9 dBm average output power is −38.7 dB (1.2%), which is 5.7/11 dB better than a standard class-B/DPA operation.

All-optical linearized Mach-Zehnder modulator.

A practical, broadband, all-optical linearization concept for a Mach-Zehnder modulator (MZM) is proposed and demonstrated. The unique transmitter design includes an amplitude modulated (AM) standard MZM with two optical outputs, where the alternative (or complimentary) output is combined with the laser carrier to create a linearizing optical local oscillator, which when coherently combined with the AM signal fully cancels 3rd order intermodulation distortion components. Using this scheme, record linearity is achieved for a non-amplified RF photonic link, with spurious free dynamic range (SFDR) of 118.5 dB.Hz2/3 and 123 dB.Hz2/3 for single and dual fiber/photodetector schemes.

Design and analysis of all optical RF transceiver using polarization modulators

All optical multiband radio transceiver is designed using Polarization Modulators. Polarization Modulators have been gaining popularity in recent times as the device is free from bias drift problem that is commonly noticed in Mach Zhender intensity modulator. Two continuous wave (CW) optical frequencies separated by 26.25 GHz are selected from optical frequency comb generator designed using two parallel polarization modulators. Two subcarrier multiplexed (SCM) signal is modulated on a comb frequency using a polarization modulator. The SCM modulated optical signal and another CW optical comb separated by 26.25 GHz are fed to a remote radio access unit (RAU) via a single mode fibre. The two signals are heterodyned in a photo detector at a remote RAU producing multi radios at 27.25 GHz and 28.75 GHz in 5G New Radio frequency band of n258 (24.25–27.5 GHz) and n257 (26.5–29.5 GHz). In the receiver part of the transceiver, the received 5G signals are modulated by a Polarization Modulator with a CW optical comb frequency and the resultant optical sidebands along with the carrier are fed to the baseband unit (BBU) at the central office via a return fiber. At the BBU the signals are heterodyned in a photo-detector with a CW comb frequency to produce the down converted baseband output at the BBU. The proposed transceiver scheme is analysed and simulation is carried out inOptisystem16® platform. BER performance of the received signal with various laser powers show that the scheme is practically implementable. In particular BER of 10−6 is obtained at the photodetector output in the transmitted (downlink) signal and returned link (uplink) signal at 2.25 dBm laser power. Two tone IMD analysis of the transmitted signal provides input and output third order intercept point at 52 dBm and 32 dBm respectively. Spurious free dynamic range (SFDR) between fundamental and 3rd order intermodulation distortion product obtained is 85 dB.Hz2/3 considering a noise floor of − 140 dBc/Hz.

Relaxation of Microwave Nonlinearity in a Cuprate Superconducting Resonator

The 2nd and 3rd order nonlinear microwave response of a superconducting YBa2Cu3O7 thin film resonator was synchronously measured using three input tones. This technique permits the local measurement, and hence mapping, of intermodulation distortion (IMD) inside the resonator. 2nd and 3rd order IMD measured with a fixed probe relaxed in remarkably different ways after the removal of a static magnetic field. The 2nd order IMD relaxed by two different magnetic processes, a fast process that appears related to bulk remanent magnetization, and a slow process that fits the description of Bean and Livingston. The 3rd order IMD relaxes by only one process which is distinct from the two processes controlling 2nd order relaxation.

A Low-Power Amplitude Modulator for QuadBand GSM/EDGE Polar Transmitter in a 65nm CMOS Process

A low power high linearity amplitude modulation path using a current reusing technique is proposed for a quad band GSM/EDGE polar transmitter. In order to reduce the current consumption and silicon area, the function of a programmable gain amplifier, AM-PM combiner and driver amplifier is realized as one stacked circuit structure. The proposed amplitude modulator is implemented in a 65nm CMOS technology and demonstrates the output power of 4 dBm and -172 dBc/Hz output noise floor level at 20 MHz offset frequency of at GSM mode. Also, the 3rd-order InterModulation Distortion (IMD3) level is below -40 dBc at all GSM/EDGE bands. The total 42 dB gain control range with a 1 dB step is achieved using a current cancelling technique without its other performance degradation. The total current consumption is 13 mA at GSM mode and 40 mA when it operates at EDGE operation from a 2.8 V supply voltage.

On the performance of a linearized dual parallel Mach–Zehnder electro-optic modulator

The performance of a dual parallel differential Mach–Zehnder modulator broadband linearization architecture is analysed. This study provides experimental and analytical results showing an enhancement up to 20dB in the 3rd-order intermodulation distortion factor at 5GHz using RF and optical asymmetrical feeding factors.

Transistor laser optical and electrical linearity enhancement with collector current feedback

The three-port quantum well (QW) transistor laser (TL) is shown to provide a unique solution for generating ultra-linear electro-optical signals. With a simple collector current feedback loop, the 3rd order intermodulation distortion in the electrical and optical output signals of the transistor laser can be suppressed by as much 18.2 dB and 8.4 dB, respectively. These results show that the TL can be used for direct electro-optical feedback linearization, because of the base QW carrier-photon interaction, without incurring signal losses at multiple stages of auxiliary external electro-optical conversion circuitry.

Mathematical Model of Laser Transmitter in Feed-Forward Mitigating Technique for Radio over Fiber System

This paper discusses a compensation system for nonlinear distortion of laser transmitter in Radio over Fiber application at frequency 5.2GHz, where feed-forward linearization technique is the applied technique in the compensation system. The paper focuses on the mathematical model of the laser nonlinear distortion which is an important tool in developing the feed-forward laser transmitter system model. The nonlinearity of the laser diode is modeled using Volterra series analysis, and the magnitudes of the laser 3rd order intermodulation distortion products (IMD3) are computed in MATLAB. The analysis result from the mathematical model has shown considerably good agreement with the results from some of the previous works. Hence, the mathematical model is deemed as useful in the modeling of feed-forward transmitter system.

Even and Odd Order Intermodulation Nonlinearity From Superconductive Microstrip Lines

Three-tone intermodulation distortion (IMD) was used to measure the even and odd order microwave nonlinearity of superconducting Tl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> CaCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> and YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> resonators. By using an off-resonance probe signal, the IMD generation is stimulated locally in the vicinity of the probe. Both 2nd and 3rd order IMD appear at the microwave resonant frequency, providing a synchronous comparison of the local even and odd order nonlinearities and a quantitative determination of the current densities that produce the intermodulation distortion. Comparison of synchronous 2nd and 3rd order IMD provides a characterization of the extent of time reversal symmetry breaking (TRSB) in the superconductor. As the probe is scanned across the resonator, the degree of TRSB is seen to vary in different regions, always exhibiting a significant rise in the 3rd order IMD at the critical temperature, T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> , consistent with expectation from the nonlinear Meissner effect. The ratio of 2nd order to 3rd order IMD current drops significantly at T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> , indicating a reduction in TRSB at the phase transition.

Accurate Distortion Prediction for Thermal Memory Effect in Power Amplifier Using Multi-Stage Thermal RC-Ladder Network

Distortion characteristics caused by the thermal memory effect in power amplifiers were accurately predicted using a multi-stage thermal RC-ladder network derived by simplifying the heat diffusion equation. Assuming a steep gradient of heat diffusion near an intrinsic transistor region in a semiconductor substrate, the steady state temperature, as well as the transient thermal response at the transistor region, was estimated. The thermal resistances and thermal capacitances were adjusted to fit a temperature distribution characteristic and a step response characteristic of temperature in the substrate. These thermal characteristics were calculated by thermal FDTD simulation. For an InGaP/GaAs HBT, a step response characteristic for a square-wave voltage signal input was simulated using a large-signal model of the HBT connecting the multi-stage thermal RC-ladder network. The result was verified experimentally. Additionally, for an RF-amplifier using the HBT, the 3rd-order intermodulation distortion caused by the thermal memory effect was simulated and this result was also verified experimentally. From these verifications, a multi-stage thermal RC-ladder network can be used to accurately design super linear microwave power amplifiers and linearizers.

Analog Performance of Multiple-quantum-well Electroabsorption Modulator

Linearity is an important property of optical devices in analog communication systems. In this paper, we study the 3rd-order intermodulation distortion (IMD3) of an InP/InGaAsP multiple-quantum-well (MQW) traveling-wave type electroabsorption modulator (TW-EAM). We observe that dips in the measured IMD3 results are different from those by general transfer curve of electroabsorption modulators (EAMs). In order to verify it, we analyse the phenomena by using the absorption coefficients according to a wavelength and a bias voltage. Thus, we can see that the dips result from the quantum-confined Stark effect (QCSE). We propose the method to enhance linearity of MQW-EAMs by using this effect in addition to the E/O response

Television Receiver Optimization in the Presence of Adjacent Channel Interference

Improved DTTV reception in a crowded spectrum can be attained by automatically shifting the front-end filter and by automatically steering the pattern of the receive antenna. This paper shows how 3rd order intermodulation distortion (IM/sub 3/) and other interference due to strong adjacent channels can be minimized and the signal to noise ratio maximized for optimally robust reception.

HIGH LINEARITY GaN HEMT POWER AMPLIFIER WITH PRE-LINEARIZATION GATE DIODE

A high linearity MMIC RF power amplifier is reported in the AlGaN/GaN HEMT technology. In order to obtain high linearity, a pre-linearization gate diode is added at the input to compensate for the nonlinear input capacitance C gs of the GaN HEMT device. Another single-ended Class B power amplifier without the gate diode is also designed for comparison. The circuit with the pre-linearization gate diode demonstrates at least 4dB improvement on 3rd order intermodulation distortion (IMD3) performance over the one without the diode over the useful power range in two-tone measurement.

Application of multilayer perceptron networks to laser diode nonlinearity determination for radio‐over‐fibre mobile communications

AbstractThis paper presents a new approach based on multilayer perceptron networks to determine the 3rd‐order intermodulation distortion levels in microwave‐intensity‐modulated GaAIAs laser diodes. The Levenberg–Marquardt algorithm is used to train the network. The results obtained from the network are in excellent agreement with the experimental results reported elsewhere. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 425–427, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20325

Linearity and CNR Improvement Technologies against Optical Reflection inFiber-Oriented Wireless Access Systems

It is important to consider optical reflection conditions when designing fiber-oriented wireless access systems around subcarrier optical transmission since the noise characteristic can be significantly degraded by optical reflection, especially if narrow spectral width devices are used. The superluminescent diode (SLD) offers stable noise and 3rd-order intermodulation distortion (IM3) characteristics that follow the ideal cubic law, even under multiple optical reflection. The SLD-predistorter combination is proposed as a way to overcome the SLD's narrow dynamic range. It is experimentally found that the predistorter reduces IM3 by 8 dB. The receiver sensitivity of a practical system that uses the SLD-predistorter combination is discussed from the viewpoint of overall design. A superimposed subcarrier modulation (SSM) technique is also proposed in order to reduce the reflection noise. We experimentally confirm that the SSM technique reduces the noise degradation and provides stable optical transmission. An SSM design methodology is presented that takes both noise and linearity into account. The SLD-predistorter and the SSM scheme make it possible to realize stable transmission performance and wider dynamic range in the presence of optical reflection.

Effect of bias and load on MESFET nonlinear characteristics

An investigation of the variation of measured and simulated nonlinear characteristics of a MESFET with bias and load resistance is reported. A discrete MESFET exhibits simultaneous low 2nd and 3rd order intermodulation distortion while yielding high gain and operating in its low noise region.

High modulation frequency low distortion 1.3 μm MQW-DFB-LDs for subcarrier multiplexed fibre-optic feeder systems

A remarkable improvement has been attained for intermodulation distortion and spectrum linewidth performance for 1.3μm DFB LDs by introducing thin barrier MQWs and short cavity configurations. Less than −85dBc in 3rd order intermodulation distortion and more than 50MHz in spectral linewidth have been simultaneously obtained from devices modulated by two 1.5 GHz signals.