Order Intermodulation Distortion Research Articles

Linearity and noise evaluation based analysis of extended source heterojunction double gate tunnel FET

This research work evaluates a performance analysis of heterostructure (SiGe/Si) double gate extended source Tunnel FET (Hetero-ES-TFET) to enhance the analog performance, linearity and noise performance. At the source-channel junction, a Hetero-ES-TFET's source is extended into the channel to increase point and line tunneling in the device. The Hetero-ES-TFET exhibits a high ION/IOFF of 3.57 × 1012 and a maximum cut off frequency fT of 54.19 GHz for optimization of device structural parameters. This analysis is conducted using a calibrated SILVACO, technology computer-aided design (TCAD) simulator. The proposed structure includes evaluation of linearity and noise performance characteristics. Furthermore, a linearity analysis as a figure of merit was conducted for the proposed device under study, including different parameters such as 3rd order intermodulation distortion point (IMD3), 3rd order intermodulation intercept point (IIP3), 2nd and 3rd order voltage intercept point (VIP2 and VIP3). The proposed Hetero-ES-TFET has achieved an incredibly high ON current and low threshold voltage. The effect of increasing source width has been examined in this work while sub-threshold swing (SS) remains unchanged during the analysis. There is an improvement in threshold voltage and ION/IOFF value by using silicon-germanium (SiGe) as a source material.

RF, harmonic distortion and linearity analysis of core-shell junctionless-FET using NQS small signal model

Abstract This paper deals with the performance analysis of Core-Shell (C-S) Junctionless (JL) FET structure in the RF domain application. The analysis begins with the non-quasi static (NQS) small signal model representation and from there the extraction of RF-parameters; and there after the harmonic distortions, linearity FOMs and Y-parameter are analyzed in detail. The device is investigated based on the variations of core/shell-thicknesses and shell-dopant concentrations. Y-parameters are evaluated from the NQS small signal model. In the RF domain analysis, the parameters such as, Cgs, Cgd, Rgs, Rgd, fT and τm are assessed to determine its RF merits. Using the two-port equivalent model, the Y-parameters (Y11, Y12, Y21, Y22) are evaluated and investigated. The second and third order harmonic distortions (HD2, HD3) are calculated using IFM method and studied in detail. In addition to that, second, third harmonic intercept voltages (VIP2, VIP3) and third order intermodulation distortion (IMD3) are also assessed for its linearity performances in domain specific applications. The proposed device is designed using the Silvaco ATLAS TCAD. The device is calibrated with the experimental data that shows a close match between the two. The proposed device is found to exhibit good linearity and very low harmonic distortion behavior by modulating the shell-doping and thickness.

Performance study of microwave photonic links by considering the effect of phase shifters and bias conditions on dual-drive dual parallel Mach–Zehnder modulator

Abstract This paper presents the performance analysis of different schemes for generating linearized photonic signal by varying phase shifter arrangements of a dual-drive dual parallel Mach–Zehnder modulator (DD-DPMZM). The RF signals at the electrodes of sub-modulators of DD-DPMZM are fed using different phase angles to generate optically modulated signals in the output. The proposed system consists of a DD-DPMZM and phase shifters. Spurious free dynamic range (SFDR) is evaluated for different configurations of sub modulators in upper and lower arm of DD-DPMZM. SFDR of 135.6 dB Hz4/5 is obtained for quadrature and optical carrier suppression modulation in upper and lower submodulators by suppressing third order intermodulation distortion completely. It is found to be high performance configuration for dual parallel Mach–Zehnder modulator based linear microwave photonic link.

Linearity and intermodulation distortion analysis of single and dual metal gate junctionless transistor

Linearity and intermodulation distortion are very crucial parameters for RFICs design. Therefore, in this work, a detailed comparative analysis on linearity and intermodulation distortion of single metal (SMG) and double metal (DMG) double gate junction less transistor (JLT) is done using TCAD silvaco suite. Furthermore, the effects of temperature fluctuation, gate length variation, and gate material engineering on the linearity performance of both devices are also studied. A few significant figures of merit, including Voltage Intercept Point 2 (VIP2), Voltage Intercept Point 3 (VIP3), Third Order Intercept Power (IIP3), 1 dB Compression Point (P1dB), Third Order Intermodulation Distortion (IMD3), and the transconductance derivative parameters First Order Transconductance (gm1), Second Order Transconductance (gm2), and Third Order Transconductance (gm3) are used to assess the device linearity and intermodulation distortion of SMG and DMG JLT's. The findings show that higher VIP2, VIP3, IIP3, 1-dB compression point and lower gm3, IMD3 values are obtained for the SMG JLT device when compared to its counterpart DMG JLT. SMG JLT, which assures strong linearity and low distortion.

Third order intermodulation and third order intercept in a directly modulated Fabry–Perot laser diode

Abstract This paper presents measurement of third order intermodulation distortion and third order intercept (TOI) in a Fabry–Perot semiconductor laser lasing at 1550.3 nm when the laser is biharmonically bias-current modulated. Keeping the modulation current of one signal fixed, the third order intermodulation power at two different frequencies has been found to increase with the increase in second signal modulation power. There is an eventual crossover or tendency to crossover in the intermodulation characteristics when the modulation current amplitudes of the channels assume the same value. The TOI has been experimentally measured. The intermodulation power appearing at two different frequencies along with their signal power dependence and measurement of TOI constitute the outcome of this paper. The typical value of spurious-free dynamic range of the modulation scheme is 70 dB.

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.

Performance optimization of high-K GAA-PZT negative capacitance FET MFIS silicon nanowire for low power RFIC and analog applications

In this article, Gate-All-Around Lead Zirconate Titanate Negative Capacitance (GAA PZT- NCFET) based Silicon Nanowire (SiNW) device architecture is investigated for the RF/Analog applications using Sentauras TCAD simulations. In this study the variation of ferroelectric layer thicknesses (tfe) has been systematically investigated. The proposed device yields higher values of on current, transconductance, cut off frequency, TFP, and Ion/Ioff ratio and lower values of off current, SS and threshold voltage, compared to baseline device. The proposed device delivers Ion, gm, fT, and TFP as 3.38 mA, 9.6 mS, 7.625 THz, and 74.85 THz V−1, respectively which are 220%, 219%, 95% and 259% respectively, higher than the baseline device. Moreover, the Ion/Ioff ratio for the proposed work is 8 × 1013 which is 7.1 × 103 times that of baseline device showing a monumental increment in this ratio. Furthermore, the effect of FE thicknesses on various linearity parameters, higher order harmonics, voltage intercept points (VIP2, VIP3), third order power intercept (IIP3) and third order intermodulation distortion (IMD3) have been investigated thoroughly. The proposed device structure offers lower values of higher order harmonics and higher values of voltage intercept points. Also, the IIP3 and IMD3 have been improved. Therefore, the linearity parameters of the device have been significantly improved when compared to the baseline device. The alluring results have been utilized to optimize the bias point of the presented device. Owing to the improved RF/Analog and linearity performance, the presented device could be utilized for imminent next generation low power RFIC applications.

Comparison of performance for third order immune photonic transmission link incorporating phase shifters and biased optimized dual parallel Mach–Zehnder modulator

Abstract This paper presents a comprehension on the linearization arrangements achieved through dual drive dual parallel Mach–Zehnder (DD-DPMZM) by changing bias voltages of sub-modulators and adjusting phases of RF signals. These arrangements comprise of a DD-DPMZM and electric phase shifters. For single sideband (SSB) modulation in sub-modulators of DD-DPMZM, power at intermodulation is found to be 43 dB and 61 dB for the linearized and convention single modulator link respectively. Thus, 28 dB of improvement in suppression of third order intermodulation distortion is reported for the first arrangement of linearization. For quadrature modulation in upper MZM and optical carrier suppression (OCS) modulation in lower modulator, almost complete suppression of IMD3 terms are demonstrated and found to be better performance arrangement for bias optimized dual parallel Mach–Zehnder modulator based linearization link.

Linear Dual-Series Mach Zehnder Modulator Employing Electrostatic Doping for Photonic Integrated Circuits

In this paper, we propose a highly linear electrostatic doping (ED) assisted dual series Mach-Zehnder modulator (MZM) suitable for photonic integrated circuits (PICs). A complete simulation study on the performance of the proposed dual series MZM is incorporated in this paper. We have analytically formulated the steady-state and the nonlinear performance of the proposed modulator and the simulation results using commercial grade photonic circuit simulator are also incorporated in support of the analytical study. Simulation results show that the proposed modulator can offer <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim\!\!16$</tex-math></inline-formula> dB of static extinction ratio (ER) with 3.2 dB of insertion loss (IL). The modulator offers approximately 10.2 dB of dynamic ER at 10 Gb/s data rate. The effect on the transfer function of the dual-series MZM due to the imbalance in the driving RF signals is also discussed supported with simulation results. The nonlinear performance of the proposed modulator is also estimated using analytical method and dual-tone test method. Results indicate that the spurious free dynamic range (SFDR) of the proposed dual series MZM for second and third order intermodulation distortions (IMD2 and IMD3) are 96.11 dB.Hz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{1/2}$</tex-math></inline-formula> , and 132.4 dB.Hz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{2/3}$</tex-math></inline-formula> , respectively. Study of the transient performance also reveals that the 3-dB electro-optic bandwidths are 11.39 GHz and 8.32 GHz for single and dual-series ED-assisted MZM, respectively.

Back-gate bias effect on the linearity of pocket doped FDSOI MOSFET

In this article, we investigate the feasibility of enhancing the linearity Figures of Merit (FoMs) by introducing pocket implant in the source/drain regions of the FDSOI MOSFET with ground plane (GP) under the influence of back-gate bias (VB) effect. The current investigations are carried out using a well calibrated industry standard simulation tool Silvaco ATLAS. The proposed device architecture shows reduction in peak electric field, improvement in effective mobility (μeff), subthreshold slope (SS), threshold voltage (VTH) & off-state current (IOFF) by rearranging the accumulated charges that can mitigate impact ionization. The improvement in these parameters leads to enhanced the fundamental transconductance term (gm) and in turn boosts the linearity, which can make it essential for RF/wireless IC designs. An investigation is performed to figure out the non-linear behaviour of proposed FDSOI MOSFET with pockets design by simulating the DC characteristics. The vital FoMs such as higher order transconductance coefficients, intermodulation distortion (IM) and input intercept point (IIP) are explicitly analysed along with the impact of VB.

A dual parallel Mach–Zehnder modulator linearization scheme based on 90° phase shifters

Abstract In this paper, a dual-drive dual-parallel Mach–Zehnder Modulator based linearization scheme is implemented by utilizing only two phase shifters and comprehensively demonstrated for a photonic transmission link. Third order intermodulation distortion is suppressed by adjusting angles of electrical phase shifters i.e. π/2 and−π/2 and a non-linear distortion immune system can be proposed for microwave photonic link. A complete suppression in intermodulation terms and 20.8 dB enhancements are found in spurious free dynamic range (SFDR). SFDR reaches 135.6 dB Hz4/5 by suppressing major spurious contributors of third order intermodulation distortions in optical domain only which ensures the improvement in performance of link against non-linear terms.

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.

Memoryless linearity in undoped and B-doped graphene FETs: A relative investigation to report improved reliability

In this work, reliability of boron-doped graphene field effect transistor (GFET) is examined by modeling the effect of doping in terms of linearity performance metrics. The key potential (VN) induced in B doped GFET is analytically modeled for various B doping concentrations. An accurate compact equivalent circuit model integrated with VN for B doped GFET is proposed to investigate the effects of memoryless nonlinearity on transconductance. The proposed equivalent circuit model is verified with the simulated results of an industry standard circuit simulation tool. The fundamental figures of merit (FOMs) such as second and third order harmonic distortion terms (HD2 and HD3), gain compression point (Ain, 1dB), second and third order intermodulation distortion terms (IM2 and IM3), second and third order input intercept points (AIIP2 and AIIP3) are mathematically modeled for doped GFET to examine the linear behaviour of the device. In addition to that, these FOMs are investigated with respect to various B doping concentrations, applied small signal amplitude, and gate-oxide capacitance. The proposed model is compatible and predicting accurate results for both B doped and undoped GFET. The simulation results are having excellent agreement with the mathematical model, which are also compared with undoped GFET and conventional MOSFET. It is also noticed that by doping the graphene sheet with boron significantly induces bandgap in it and hence enhances the linear behaviour of the B doped GFET. Hence, reliability of doped GFET is improved while comparing with undoped GFET and promises highly desirable linearity requirement in analog/RF applications.

A photonic transmission link with enhanced dynamic range by incorporating phase shifters in dual drive dual parallel Mach–Zehnder modulator

Abstract A linearization scheme is proposed for microwave photonic link to enlarge spurious free dynamic range using a dual-electrode dual parallel Mach–Zehnder modulator (MZM). This scheme employs phase control method to improve performance of the link by adjusting phase of radio frequency (RF) signals and bias voltages of optical modulator. Optical single sideband modulation is achieved through sub-modulators of dual parallel MZM which increases efficiency of the link. The simulated results show that third order intermodulation distortion is suppressed by 28 dB when the input RF signals are 9.1 and 9.5 GHz and noise floor is at −161 dBm/Hz. The spurious free dynamic range is also improved by 12.6 dB.

Study on impact of ferroelectric layer thickness on RF /analog and linearity parameters in ferroelectric‐FinFET

In this paper, we systematically investigated the effect of ferroelectric (FE) layer thickness (tFE) on transfer and RF/analog characteristics such as transconductance (gm), total gate capacitance (Cgg), cut off frequency (ft), transconductance frequency product, and unilateral power gain in Ferroelectric-FinFET (Fe-FinFET) through 3D TCAD simulator. Further, we highlighted the influence of tFE on linearity figure of merits (FoMs), higher order harmonics (gm2 and gm3), voltage intercept points (VIP2 and VIP3), third order power intercept point (IIP3), third order intermodulation distortion (IMD3), and 1-dB compression point (1-dB comp. Pnt.) for Fe-FinFET. Moreover, the harmonic distortion (HD) parameters like second and third order harmonic distortion (HD2 and HD3) and total harmonic distortion (THD) are reported taking tFE as a parameter. The noise spectral densities of Fe-FinFET taking tFE as parameter is also highlighted. The scaling of tFE has a significant impact on RF/analog parameters and these RF/analog FoMs are a function of tFE. It is also perceived that linearity and HD parameters are dependent on scaling of tFE. Results reveal that with increase in tFE, RF/analog characteristics degrades, whereas, superior linearity FoMs is achieved. It is also seen that HD parameters are improved with increased in tFE value. The increased in tFE leads to increase in noise spectral densities. Finally, the comparative study of electrical parameters of this work with the existing literature is investigated.

Influence of columnar defects on magnetic relaxation of microwave nonlinearity in superconducting YBCO resonator devices

Intermodulation distortion (IMD) of microwave signals incident upon a superconducting YBa2Cu3O7−x thin film sample on a LaAlO3 substrate is shown to relax as the sample magnetization also relaxes, revealing the signature of fluxon decay in the microwave distortion. The sample contained a microchannel of columnar defects that was introduced using heavy ion beam irradiation. After exposure to and then removal of a low strength static magnetic field, IMD relaxed due to thermal activation of fluxons over the surface barrier. This process influenced second and third order IMD differently, visible in the differing functional form of the IMD in time and the temperature dependence of the relaxation function. The presence of columnar defects in the test sample suppressed thermal activation by pinning of fluxons, notably with complete suppression of relaxation in third order IMD at low temperatures. Higher order IMD was found to relax with the same functional form as the second and third order IMD of the same parity.

Analysis of distortion reduction in 1.3 μm transistor laser using Schottky diode based predistortion network

A Schottky diode based linearization network is investigated for distortion reduction in 1.3 μm Transistor Laser for the first time. Second harmonic and third order intermodulation distortion (IMD3) are numerically analyzed in transistor laser using single and dual Schottky diode based predistortion techniques. An improvement of 13.56 dB and 15.53 dB are obtained for IMD3 under single and dual Schottky diode predistortion techniques respectively. Further, an enhancement in SFDR of 60.54 dB Hz2/3 and 62.92 dB Hz2/3 are observed for the above schemes. Moreover, the bandwidth is improved to 12 GHz and 13.8 GHz for single and dual Schottky diode predistortion techniques, whereas it is only 10.96 GHz without predistortion, under similar bias conditions.

Anti-Series Varactor Network With Improved Linearity Performances in the Presence of Inductive and Capacitive Parasitics

This paper proposes a varactor-based circuit technique intended for amplitude and phase control, with improved linearity in the presence of parasitic capacitances and parasitic inductances. The mechanism causing linearity degradation in an anti-series varactor network that includes significant parasitic elements - a key aspect that, to our knowledge, has never been reported - is first studied using an analytical approach based on multi-tone excitation. It is demonstrated that simply optimizing the ratio of diode sizes is insufficient to circumvent this linearity degradation. The underlying linearity degradation concept serves as the basis for the introduction of a modified anti-series controllable capacitance, followed by a design and practical implementation. Experimental validations with multi-tone and modulated signals demonstrate improved linearity performances with respect to the state-of-the-art when parasitic capacitances and inductances are significant. Moreover, it is shown that the complete varactor-based circuit topology proposed here, which uses the proposed modified anti-series controllable capacitance in conjunction with a second-harmonic trap filter, constitutes a very attractive alternative to the state-of-the-art anti-series/anti-parallel topology, since it reduces the required number of diodes by a factor of 2. Measurements on discrete-component designs operating at 3.6GHz, hence with significant parasitic effects, demonstrate that the proposed circuit topology improves the 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> order intermodulation distortion levels by 10.6dB and 6.6dB at output powers of 10dBm and 18dBm respectively, in comparison with the state-of-the-art topology. Measurements with a 16QAM modulated signal also show 3.9dB improvement in ACPR at 18dBm. These performances constitute improved state-of-the-art results in anti-series hyper-abrupt varactor-based electronic control.

Experimental insight into the third‐order intercepts and nonlinear distortion of GaN HEMTs

This research is about investigating the third-order intercept point (TOI) and nonlinear distortion level (NDL) for two GaN HEMTs of different gate lengths with temperature and frequency. As a multi-biasing, input power, frequency and temperature-dependent term; the TOI point and as well as the nonlinear distortion level are particular figures merit relevant to the third-order intermodulation distortion (IMD3) product. The primary results are the output referenced TOI reduced whereas the input referenced TOI raised as the frequency goes higher and the lower gated device exhibits a bit greater magnitude. Over the temperature range measured; the magnitude of TOI and nonlinear distortion considerably changed in accordance to the performance of third order intermodulation distortion (IMD3) component. This investigation of TOI is used to determine what extent distortion is generated, and comparing that to the entryway of the antenna provides a clear strategy for determining if the spec can be met or not. However, distortion level investigation is a critical point to choose the best biasing preference with the device's inlet measurements to establish a solution that fits with the intended usage.

Performance Tuning and Reliability Analysis of the Electrostatically Configured Nanotube Tunnel FET with Impact of Interface Trap Charges

This paper examines, an electrostatically configured Nano-Tube Tunnel Field-Effect Transistor (ED-NTTFET). During the fabrication process, different charges such as fixed charge, oxide trapped charge, and interface trapped charge have been produced at the gate oxide interface. So the effect of positive and negative interface trapped charge (+ITC & -ITC) has been proposed for the first time for electrostatic doped-based Nano-Tube TFET (ED-NTTFET). There are two types of techniques, charge plasma (EP) based technique and electrostatic doped (ED) technique is used to produce the induced charge in the intrinsic channel region. In the charged plasma (CP) technique, the metal work-function is used to produce the induced charge while in the electrostatic doped (ED) technique electrostatic voltage is applied across the source and drain side to produce the induced charge in the intrinsic channel region. Analysis of the various device parameters such as hole/electron concentration, energy diagram, electric field, tunneling rate, driving current, OFF current, ON current, ION/IOFF, threshold voltage, and average sub-threshold slope in the presence of interface trapped charge (ITC). Due to positive interface trapped charge electric field and band to band tunneling rates are improved. So the drain current of the device also improved from the 2.94*10−5 A/um2 to 5.35*10−5A/um2. Linearity parameters such as second & third order trans-conductance (gm2 & gm3), second & third order voltage intercept point (VIP2 & VIP3), second & third order harmonics distortions (HD2 & HD3) and intermodulation distortions (IMD) have been discussed. The negative interface trapped charge (-ITC) degrades the linearity parameter of the device and the positive interface trapped charge (+ITC) improves the linearity parameter of the device. The proposed electrostatic doped nano-tube TFET (ED-NTTFET) produced higher cut-off frequency at lowers operating gate voltage.