Third-order Intermodulation Research Articles

A 28–34-GHz Stacked-FET Power Amplifier in 28-nm FD-SOI With Adaptive Back-Gate Control for Improving Linearity

Adaptive back-gate control of a stacked-FET power amplifier (PA) in 28-nm fully depleted silicon-on-insulator (FD-SOI) CMOS is demonstrated for the 64-QAM signal at 28 and 31 GHz. Adaptive bias control (ABC) is applied to the back gate to effectively enhance the linearity of PAs for wideband waveforms with up to an 800-MHz envelope frequency. Third-order intermodulation distortion (IMD3), which degrades the linearity of a PA, is improved by adjusting back-gate biases of the stacked-FET PA according to the input power level without any concerns about wideband operation. From 28 to 34 GHz, the presented PA provides P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub> and PAE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P1dB</sub> of 16.4-dBm and 37.3%, respectively. At 28 and 31 GHz, the measured P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub> and PAE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P1dB</sub> are 17.4 and 16.9 dBm, 37.7% and 38.8%, respectively, with a compact core area of 0.088 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The rms EVM improvement due to the linearity enhancement with the adaptive back-gate control is experimentally demonstrated to be around 2.6 and 1.8 dB for 8.65-dB PAPR single-carrier 64QAM signals with 8-dB back-off at 28 and 31 GHz, respectively.

Analytical Synthesis of High-Pass, Band-Pass and Low-Pass Biquadratic Filters and its Quadrature Oscillator Application Using Current-Feedback Operational Amplifiers

In this paper, a method of realizing voltage-mode (VM) non-inverting high-pass filter (HPF), band-pass filter (BPF), low-pass filter (LPF), and inverting low-pass filter (ILPF) transfer functions structure with two grounded capacitors and four resistors through an analytical synthesis method is presented. The synthesis structure of the VM biquadratic filter consists of a voltage proportional block and two voltage lossless integrators based on the use of current feedback operational amplifiers (CFOAs). It is demonstrated that the derived biquadratic filter structure can simultaneously realize VM HPF, BPF and ILPF transfer functions or VM BPF and LPF transfer functions at a high-input impedance terminal. The VM biquadratic filter can independently adjust the resonance angular frequency and quality factor. By slightly modifying the proposed biquadratic filter, a VM quadrature sinusoidal oscillator can be achieved. The proposed biquadratic filter and quadrature oscillator have been simulated by OrCAD PSpice and appropriate hardware has been implemented with AD844-type CFOAs. In order to reduce power consumption, reduce chip area, reduce costs, and improve system integration, integrated VM CFOA-based biquadratic filter circuits and quadrature oscillator circuits are very important. The proposed filter and quadrature oscillator have been further fabricated in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18~\mu \text{m}$ </tex-math></inline-formula> 1P6M CMOS process technology. The entire chip area is 0.974 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , including a filter chip cell and an oscillator chip cell. Under the supply voltage of ±0.9 V, the total power dissipation of the filter chip cell is 5.4 mW, and the figure-of-merit (FOM) of filter chip cell is 66.7%. The measured value of the third-order intermodulation distortion of the filter chip cell is −55.29 dBc and the third-order intercept point is 19.9 dBm. The measured phase noise of CFOA-based filter chip cell at 1 kHz offset is less than −99.76 dBc/Hz.

EVALUATION OF THE INFLUENCE OF THE VALUE OF THE DYNAMIC RANGE OF THE RADIO RECEIVER ON THE NOISE IMMUNITY OF RECEIVING SIGNALS WITH QUADRATURE AMPLITUDE MODULATION

The improvement of digital communication lines of radio information transmission systems in the direction of increasing the complexity of the signal-code structures used, increasing the speed of information exchange, the use of modern channel compaction technologies, on the one hand, and the high complexity of the surrounding electromagnetic environment, on the other hand, objectively determines the need to improve the radio receiving systems of digital communication lines in the direction of increasing their noise immunity. In this regard, in order to justify the technical requirements for noise immunity to radio receiving systems of the designed transmission lines, it is advisable to take into account the basic indicators of the quality of functioning of the radio receiving device, in order to obtain analytical expressions and graphical dependencies for evaluating the noise immunity of receiving signals with more complex combined types of modulation (QAM-64 and higher), used and planned for use. Of the large number of indicators that characterize the dynamic range, the most informative and sufficiently characterize the quality of the linear path are: the dynamic range for reducing the transmission coefficient (compression) by 1 dB and the dynamic range for third-order intermodulation distortion. The effect of interference received on the side channels (which include combination and mirror), as well as on neighboring channels, limits the lower limit of the dynamic range of the receiving device and, as a result, reduces the resulting signal-to-noise ratio at the output. The degree of suppression of the combination channels is determined, first of all, by the frequency plan and the linearity of the amplitude characteristic of the mixer of the first frequency converter, the mirror channel – the quality of filtering the mirror frequencies in the input preselector, the neighboring channel – the selectivity of the filters of the main selection. In this article, an analytical model and the resulting graphical dependencies are developed to assess the degree of influence of compression distortions on the noise immunity of receiving multi-position quadrature-amplitude modulated signals, and the requirements for the value of the dynamic range of radio receiving systems are theoretically justified.

Frequency and Power Dependence of Passive Intermodulation in Connectors With Contact-Material Nonlinear Modeling

Passive intermodulation (PIM) is generally regarded as an unavoidable interference in radio frequency (RF) circuit and system, which exhibits dynamic characteristics with the change of signal frequencies and powers. In this letter, a prediction model of frequency and power dependence of PIM is theoretically proposed and experimentally verified. Physical nonlinearities of truncated distortion and tunneling effect are introduced to provide explanations for the contact surface-induced PIM. Considering nickel is the nonlinear material source in connector coating, the impact of signal frequency on PIM is investigated by calculating the current density in the magnetic area coupled with skin effect theory. Through the combination of two PIM generation mechanisms, a novel equation-based equivalent circuit model is provided to simulate the third-order intermodulation (IM3) powers in connector resulting from different signal frequencies and powers. The frequency and power dependence characteristics are observed from both the theoretical predictions and measurements.

Linearized phase modulated microwave photonic link based on integrated ring resonators.

An on-chip linearization method for phase modulated microwave photonic link based on integrated ring resonators is proposed. By properly tailoring the phase and amplitude of optical carrier band and second-order sidebands, the third-order intermodulation distortion (IMD3) components can be suppressed. Theoretical analysis are taken and a proof-of-concept experiment is carried out. Experimental results demonstrate that IMD3 is suppressed by 21.7 dB. When the noise of the link is properly optimized, an SFDR of 112.7 dB·Hz2/3 can be achieved. This opens the possibility of integrating linearization into a functional photonic integrated circuit.

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.

A wideband low power merged balance-balun-LNA and I/Q-mixer

This paper presents a low power wideband RF receiver front-end in CMOS 180 ​nm technology that operates between 0.3 and 4.7 ​GHz. The mixer has a quadrature current commutating gilbert cell configuration that utilizes a novel broadband noise-canceling balanced balun-LNA as the transconductance stage. The noise-canceling balun LNA utilizes an additional noise-reduction technique that enhances its performance noticeably. Both of the common gate and common source stages of balun LNA are matched by employing equal-sized transistors that are biased with the same currents and load resistances. This technique results in superior symmetry, enhanced noise, and linearity performance under reduced power consumption. Post-layout simulation results show that the implemented balun LNA-I/Q-mixer has a conversion gain of 14.05 ​dB. The second and third-order intermodulation intercept points are +42.13 dBm and +4.13 dBm, respectively. The double-sideband NF is 4.74 ​dB. The proposed structure consumes only 6.7 ​mW from a 1.8 ​V supply and occupies a 0.056 ​mm2 chip area.

A 24-GHz RF Transmitter in 65-nm CMOS for In-Cabin Radar Applications

A 24-GHz direct-conversion transmitter is proposed for in-cabin radar applications. The proposed RF transmitter consists of an I/Q up-conversion mixer, an I/Q local (LO) oscillator generator, and a power amplifier. To improve the linearity of the I/Q up-conversion mixer, an inverter transconductor with third-order intermodulation (IM3) distortion cancellation is proposed. To improve the I/Q balancing performance of the I/Q LO generator, a poly-phase filter, including parasitic line inductance, is proposed. By employing a highly linear I/Q up-conversion mixer and a balanced I/Q LO generator, the 24-GHz direct-conversion transmitter achieves high linearity and I/Q balancing characteristics. It is fabricated in a 65-nm CMOS process and consumes 150 mW. It shows an OP1dB of 8.6 dBm, an LO leakage of −48 dBc, and an image rejection ratio of −49 dBc for the entire operating band from 24 GHz to 24.5 GHz.

Electro-Optic Modulator for Compensation of Third-Order Intermodulation Distortion Using Frequency Chirp Modulation

Electro-Optic Modulator for Compensation of Third-Order Intermodulation Distortion Using Frequency Chirp Modulation

A Dual-Broadband Dual-Polarized Directional Antenna for All-Spectrum Access Base Station Applications

A dual-broadband, dual-polarized directional antenna with an electrical down-tilted beam is designed for all-spectrum access base station applications. Three columns of elements are deployed in the manner that six lower-band elements are placed in the center column while the eleven upper-band elements are arranged in the other two columns. Moreover, each column of elements are fed by two ports, which makes the proposed antenna suitable for multiple-input-multiple-output (MIMO) applications. To verify the design concept, a prototype is fabricated and measured. The measurement results confirm that the proposed antenna achieves a bandwidth of 31.6% (698-960 MHz) for VSWR<; 1.5 in the lower band and a bandwidth of 44.5% (1710-2690 MHz) for VSWR<; 1.5 in the upper band, covering all the frequency bands for 2G/3G/LTE systems and 700 MHz/2.6 GHz frequency bands. The measured gains are 17.4 ± 0.9 dBi, 17.3 ± 0.8 dBi, and 14.4 ± 0.9 dBi for the antenna port1, port2, and port3, respectively, while the third-order passive intermodulation (PIM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) is larger than 115 dBm at all frequencies. With these distinctive advantages, the proposed antenna is suitable for multi-band base stations.

Effects of Environmental Temperature on Passive Intermodulation in Electrical Connectors

Environmental temperatures may affect the high-frequency electrical performance of passive components, including passive intermodulation (PIM) characteristics. This work proposes a theoretical model of the third-order intermodulation distortion (IM3) signal as a function of the material properties and contact characteristics in a connector. A cross-sectional model of the inner conductor supported by finite-element analysis (FEA) simulations was used to investigate the effect of temperature on the current density distribution in different material regions and its impact on nonlinear performance. Based on electrical contact theory and temperature-dependent modeling, mathematical expressions were developed to calculate the impact of the various contact parameters, such as contact pressure, contact area, and contact resistance. Combining the effects of both material nonlinearity and contact nonlinearity, the IM3 product powers resulting from coaxial connectors associated with temperature change were predicted theoretically. A series of experiments were designed and conducted to measure the IM3 product powers of connectors for a variety of environmental temperatures. The model predictions show a good correlation with these experimental results.

Аdaptive broadband low-noise RF amplifier

Adaptive broadband low-noise radio frequency amplifiers (ABLNRFA) are widely used in the construction of systems for protecting radio receiving paths from nonlinear damage in a non-stationary electromagnetic environment (EME). One of the promising focus areas on the creation of ABLNRFA is the development of devices in the class of circuits with switched networks. The creation of such devices has certain features, since, along with the need to ensure a low noise figure and digital control of the regulation characteristic, it is required to provide high linearity and a large dynamic range (DR) of the device. This paper presents the results of the logical-heuristic synthesis of ABLNRFA with an adaptively adjustable transducer gain, which changes due to switching of transformer feedback circuits. In order to check the functional and technical characteristics of the synthesized ABLNRFA and optimize its parameters, a model was developed and studied in the ADS environment. The proposed ABLNRFA technical solution provides a discrete (23, 14, 10 and 5 dB) wideband change in the transmission coefficient, while the DR for third-order intermodulation in terms of a 1 MHz band is 83, 92, 98 and 104 dB, respectively. A step change in the transducer gain in the circuit of the lossless feedback circuit developed by ABLNRFA avoids the accumulation of additional noise in the structure and provides a low-noise figure that does not exceed 1 dB. The technical characteristics of ABLNRFA allow one to adaptively increase the overload capacity of the radio receiving path with a proportional expansion of its DR in the conditions of non-stationary EME, and thus increase the efficiency of the level protection system against nonlinear damage to the receiving paths of radio communication, radar and radio navigation.

Wideband 23.5–29.5-GHz Phased Arrays for Multistandard 5G Applications and Carrier Aggregation

This article presents a 23.5–29.5-GHz $8\times 8$ phased array for wideband multistandard applications. The array is based on wideband high-performance $2\times 2$ transmit/receive (TRX) quad-beamformer chips with 6 bit of phase control and 8 bit of gain control. The antenna is designed using a stacked-patch structure combined with a two-stage impedance matching network to enhance its bandwidth. The $8\times 8$ phased array achieves an effective isotropic radiated power (EIRP) of 54.8 dBm at P1dB with a 3-dB bandwidth of 23.5–30.5 GHz and can scan to ±60° in the azimuth plane and +/40° in the elevation plane with excellent patterns with a single-point calibration at 27 GHz. Measured error vector magnitude (EVM) for a 64-QAM 200 and 800-Mbaud waveforms result in a system EVM of 5% (−26 dB) in the TX mode at an average EIRP of 46–47 dBm at 24.5–29.5 GHz. Also, the wideband array is capable of 16-QAM 24-Gb/s links with an EVM <16% over all scan angles. An interband carrier aggregation (CA) system is also demonstrated with the wideband array using 200-Mbaud 64-QAM waveforms with 25- and 29-GHz carriers. The phased-array phase and amplitude settings are chosen such that the 25- and 29-GHz waveforms are radiating simultaneously at the same angle with low scan loss, resulting in an efficient system. Also, the out-of-band third-order intermodulation products generated by the power amplifier on each element are filtered out by the antenna. CA measurements with up to 50° scan angles are demonstrated with low EVM. To the best of our knowledge, this is the first demonstration of CA in millimeter-wave fifth-generation (5G) systems.

Linearized Photonic Microwave and mm-Wave Mixer With Dispersion-Induced Power Fading Compensation

A novel photonic microwave and millimeter-wave (mm-wave) mixer with simultaneous third-order intermodulation distortion (IMD3) suppression and dispersion-induced power fading compensation is proposed and experimentally demonstrated. In our proposed scheme, a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator is used to modulate RF/IF and LO signals. The bias voltages of the main modulators are adjusted to compensate dispersion-induced power fading. When the polarization state of the modulated signal and the attenuation of the RF signal are properly adjusted, IMD3 distortion can be suppressed. In the experiment, relatively flat microwave and mm-wave signals from 11 to 35 GHz are obtained through 4and 50-km fiber transmission, while the measured spurious free dynamic range (SFDR) is 112.9 dB·Hz4/5. In addition, an upconverted 16 quadrature amplitude modulation (16 QAM) vector signal with a carrier frequency of 19.3 GHz is obtained and the measured constellation diagrams and error vector magnitudes are given after transmission over different fiber lengths (back to back, 4 and 50 km).

A sub-1V dual-path noise and distortion canceling CMOS LNA for low power wireless applications

This paper presents a 0.8 ​V supply voltage low noise amplifier (LNA) with high linearity for low power wireless applications. To reduce both second- and third-order intermodulation components (IM2 and IM3), the proposed structure creates equal common-mode (CM) currents with the opposite sign by cascading two differential pairs with a cross-connected output and improves linearity. Using resistive feedback together with noise and distortion canceling technique mutually cancel noise and nonlinearity of both main and auxiliary amplifiers. Combining transformer-based gm-boosting and current reuse techniques makes the presented LNA a superior candidate for low power radios. Detailed analysis and simulations are provided to show the effectiveness of the proposed LNA structure. Simulation results using 65 ​nm CMOS process reveal that the linearized low power LNA achieves over 25 ​dB voltage gain, 2.7 ​dB NF, +10.1 dBm IIP3, and average IIP2 of more than +57 dBm while consuming 870 ​μW.

A novel source material engineered double gate tunnel field effect transistor for radio frequency integrated circuit applications

Tunnel field effect transistors (TFETs) have proved their potential for many possible electronic circuit applications. However, with the variety of TFET structures being worked upon it has been an unresolved challenge to optimize them for the applications to which they are best suited. In this paper we present a detailed comparative analysis of the linearity distortion and the radiofrequency (RF) performance parameters of a proposed heterojunction Mg2Si source double gate TFET (HMSDG-TFET) and a conventional homojunction Si source DG-TFET (SSDG-TFET). A source material engineering scheme is utilized to implement a staggered type 2 heterojunction at the source–channel junction by replacing the source material with Mg2Si (a low band gap material) to enhance the ON current (2.5 × 10–4 A µm−1), reduce the threshold voltage (0.26 V) and achieve a steeper subthreshold swing (10.05 mV decade−1). For linearity and distortion analysis, the figure of merit (FOM)-like higher-order transconductances, second- and third-order voltage intercepts, third-order intercept point, third-order intermodulation distortion, zero crossover point, 1 dB compression point, second-order harmonic distortion, third order harmonic distortion and total harmonic distortion have been examined. To portray the possible application of devices under consideration for RF integrated circuit applications, both structures are investigated for RF FOMs such as power gains, cutoff frequency (fT), maximum oscillation frequency (F max) and admittance parameters. Investigations carried out using a Silvaco ATLAS device simulator tool revealed that with fT approximately three orders higher (0.49 THz) and F max approximately two orders higher (0.9 THz) than that of a SSDG-TFET, the HMSDG-TFET is an appropriate candidate for use in high-frequency, high-linearity, low-distortion and low-power analog/RF applications.

A 0.07-mm2 162-mW DAC Achieving &gt;65 dBc SFDR and &lt; −70 dBc IM3 at 10 GS/s With Output Impedance Compensation and Concentric Parallelogram Routing

A digital-to-analog converter (DAC) with small-size non-cascoded current cells is proposed to achieve small area, low-power consumption, and high linearity over a wide bandwidth. An output impedance compensation (OIC) technique using a compensation resistor, implemented by a PMOS with code-dependent gate voltage control, is proposed to remedy the nonlinearity induced by the insufficient output impedance of the non-cascoded current cells. In addition, a proposed concentric parallelogram routing (CPR) technique, in which the subcells of each current cell are arranged such that they form a parallelogram shape with a common centroid, is used to reduce both the mismatch error and the routing-induced timing skew among the current cells. The DAC, implemented in a 28-nm CMOS process, achieves >65-dBc spurious-free dynamic range (SFDR) and < −70-dBc third-order intermodulation distortion (IM3) over the entire Nyquist bandwidth at 10 GS/s while consuming 162 mW from a single 1.1 V supply.

A Linearity Improvement Front End with Subharmonic Current Commutating Passive Mixer for 2.4 GHz Direct Conversion Receiver in 0.13 μm CMOS Technology

Direct conversion receiver (DCR) architecture is a promising candidate in the radio frequency (RF) front end because of its low power consumption, low cost and ease of integration. However, flicker noise and direct current (DC) offset are large issues. Owing to the local oscillator (LO) frequency, which is half of the RF frequency, and the absence of a DC bias current that introduces no flicker noise, the subharmonic passive mixer (SHPM) core topology front end overcomes the shortcoming effectively. When more and more receivers (RX) and transmitters (TX) are integrated into one chip, the linearity of the receiver front end becomes a very important performer that handles the TX and RX feedthrough. Another reason for the requirement of good linearity is the massive electromagnetic interference that exists in the atmosphere. This paper presents a linearity-improved RF front end with a feedforward body bias (FBB) subharmonic mixer core topology that satisfies modern RF front end demands. A novel complementary derivative superposition (DS) method is presented in low noise amplifier (LNA) design to cancel both the third- and second-order nonlinearities. To the best knowledge of the authors, this is the first time FBB technology is used in the SHPM core to improve linearity. A Volterra series is introduced to provide an analytical formula for the FBB of the SHPM core. The design was fabricated in a 0.13 μm complementary metal oxide semiconductor (CMOS) process with a chip area of 750 μm × 1270 μm. At a 2.4 GHz working frequency, the measurement result shows a conversion gain of 36 dB, double side band (DSB) noise figure (NF) of 6.8 dB, third-order intermodulation intercept point (IIP3) of 2 dBm, LO–RF isolation of 90 dB and 0.8 mW DC offset with 14.4 mW power consumption at 1.2 V supply voltage. These results exhibit better LO–RF feedthrough and DC offset, good gain and NF, moderate IIP3 and the highest figure of merit compared to the state-of-the-art publications.

Second-order Intermodulation Low Frequency Blocking Effect and Mechanism for Communication Radio under Electromagnetic Radiation

In order to reveal the complex electromagnetic environment effects mechanism of communication radio, the blocking effect of single-frequency and out-of-band dual-frequency electromagnetic radiation for the ultra-short wave digital communication radio is experimentally studied by irradiation method. The rule of single-frequency electromagnetic radiation effect and the susceptible bandwidth are determined. The experimental data show that the tested radio is 9～23 dB more susceptible to out-of-band dual-frequency third-order intermodulation blocking than single-frequency electromagnetic radiation blocking. A sensitive phenomenon of dual-frequency electromagnetic radiation which can neither be explained by the dual-frequency non-intermodulation superposition mechanism nor by the third-order intermodulation mechanism has been found in the experiment.

Linearized analog photonic down-conversion link based on a dual-polarization quadrature phase-shift keying modulator

A novel linearized analog photonic down-conversion link based on an integrated dual-polarization quadrature phase-shift keying (DP-QPSK) modulator is proposed and experimentally verified. Radio frequency and local oscillator signals are fed into the DP-QPSK modulator via an electrical attenuator, respectively. By adjusting the ratio of the two attenuators, the third-order intermodulation distortion can be eliminated based on balanced detection. The scheme is simple and compact and it achieves full spectrum utilization because of using no filter. Experimental results show that the spurious free dynamic range is improved by 16.43 dB for a two-tone signal and the error vector magnitude is improved by 6.16% for a 100-MSym/s 16-quadrature-amplitude-modulation signal.