Monolithic Microwave Integrated Circuit Design Research Articles

Optimizing MMIC performance: The synergy of AI models and heterogeneous integration process

AbstractThis study presents a novel approach for optimizing the parameters of monolithic microwave integrated circuit (MMIC) functional units using machine‐learning techniques and multi‐objective optimization algorithms. We utilize advanced machine‐learning methods, including random forest, artificial neural networks (ANNs), and recurrent neural networks (RNNs), to construct highly accurate models that predict the performance of these units. These models are subsequently integrated with a multi‐objective optimization algorithm, specifically the multi‐objective particle swarm optimization (MOPSO), to generate inverse design solutions for both the geometric designs of the units and the fabrication parameters of the heterogeneous integration process. Our approach, which has been validated through chip fabrication and testing, has demonstrated its robustness as a tool for achieving optimal MMIC designs. It not only reduces the design time but also enhances the manufacturability of MMICs, thereby opening new avenues in microwave and RF circuit design.

A multi‐variable double impedance matching network design algorithm with design example of a low noise amplifier

In this article, we propose a matching network design algorithm based on the segmentation of the real and imaginary part of optimum source impedance curve with respect to space variable x $$ x $$ and frequency ω $$ \omega $$ , respectively. The impedance curve (comprising of real and imaginary parts) is approximated as a collection of n $$ n $$ linear segments, represented by the weighted sum of n $$ n $$ semi-infinite linear functions. Using the numerical method, optimum weight vectors that maximize transducer power gain are obtained to model the real and imaginary parts of the source impedance curve. We get the values of optimum weight vectors and the rational input impedance function for the matching network, which are then synthesized in the desired topology by a continued partial fraction. Experimentally, we validate the novelty of the proposed method by designing matching networks of a wideband custom monolithic microwave integrated circuit (MMIC) low noise amplifier (LNA) in 1.3–2.3 GHz frequency band. The measured results of the designed LNA are significantly close to the simulated results. We bias our LNA at (5 V, 150 mA) and achieve a maximum noise figure of 1.25 dB, OP1dB of 26 dBm, and an average TOI of 38 dBm. Moreover, our design of custom LNA MMIC has an integrated ESD structure while occupying only 0.32 mm2 of chip area.

Investigation on Temperature Behavior for a GaAs E-pHEMT MMIC LNA.

In order to investigate the temperature behavior for monolithic microwave integrated circuits (MMICs) under alpine conditions, the performance parameters of a 0.4–3.8 GHz gallium arsenide (GaAs) enhancement pseudomorphic high-electron-mobility transistor (E-pHEMT) low-noise amplifier (LNA) are tested at different temperatures. The typical temperatures of −39.2 °C, −32.9 °C, −25.3 °C, −11.3 °C, −4.9 °C, 0 °C and 23 °C are chosen as the alpine condition. The major performance indexes including the direct current (DC) characteristics, S-parameters, stability, radio frequency (RF) output characteristics, output third-order intersection point (OIP3) and noise figure (NF), which were inspected and analyzed in detail. The results show that the DC characteristics, small-signal gain (S21), RF output characteristics and NF all deteriorate with the rising temperature due to the decrease in two-dimensional electron gas mobility (). Contrary to this trend, the special design makes stability and OIP3 increase. For further application of this MMIC LNA under alpine conditions, several measures can be utilized to remedy performance degradation. This paper can provide some significant engineering value for the reliable design of MMICs.

Bridging the Gap between Physical and Circuit Analysis for Variability-Aware Microwave Design: Modeling Approaches

Process-induced variability is a growing concern in the design of analog circuits, and in particular for monolithic microwave integrated circuits (MMICs) targeting the 5G and 6G communication systems. The RF and microwave (MW) technologies developed for the deployment of these communication systems exploit devices whose dimension is now well below 100 nm, featuring an increasing variability due to the fabrication process tolerances and the inherent statistical behavior of matter at the nanoscale. In this scenario, variability analysis must be incorporated into circuit design and optimization, with ad hoc models retaining a direct link to the fabrication process and addressing typical MMIC nonlinear applications like power amplification and frequency mixing. This paper presents a flexible procedure to extract black-box models from accurate physics-based simulations, namely TCAD analysis of the active devices and EM simulations for the passive structures, incorporating the dependence on the most relevant fabrication process parameters. We discuss several approaches to extract these models and compare them to highlight their features, both in terms of accuracy and of ease of extraction. We detail how these models can be implemented into EDA tools typically used for RF and MMIC design, allowing for fast and accurate statistical and yield analysis. We demonstrate the proposed approaches extracting the black-box models for the building blocks of a power amplifier in a GaAs technology for X-band applications.

Comparing Novel MMIC and Hybrid Circuit High Efficiency GaAs Schottky Diode mm-Wave Frequency Doublers

A novel Schottky diode frequency doubler in E-band, using biased series-connected diodes in the output waveguide, is reported. The doubler was implemented using a GaAs Schottky Monolithic Microwave Integrated Circuit (MMIC) process with integrated capacitors and beam leads. A comparison is made with a hybrid doubler using a more conventional single-ended configuration with two discrete diodes in a planar transmission line circuit. Both devices exhibit excellent performance over the 67–78 GHz design bandwidth, with the novel MMIC design producing 25 to 55 mW at 12 to 22% power conversion efficiency. Good agreement of measurements with simulations was also found.

Compact 2–18 GHz on‐chip balun based on centrosymmetric spiral transformers

A novel broadband balun based on centrosymmetric spiral transformers is proposed. Two parallel circular spiral transformers comprise the proposed balun, which is different from the Marchand structure. The equivalent coupled line model demonstrates that asymmetric structure is helpful to realise the appropriate balun with good amplitude balance and low return loss. Finally, combined with the structural characteristics of the spiral transformer in monolithic microwave integrated circuit designs, a centrosymmetric structure with compact size is adopted. The balun is designed and fabricated in WIN's IP2M process and its core size occupies an area of 700 μ m × 300 μ m . The simulation and measurement agree well, exhibiting a bandwidth covering from 2 to 18 GHz with good return loss, flat insertion loss and high stability of 180° phase difference.

Enhancing performance of a InGaP/GaAs VCO by means of a switching architecture

The introduction of a compact switching architecture in the design of a monolithic microwave integrated voltage-controlled oscillator (VCO) is described, that is able to provide enhanced characteristics in term of both linearity and tunability. The proposed solution is applied to the design of a C-band GaAs MMIC (monolithic microwave integrated circuit) VCO. The chip has been realised with the heterojunction bipolar transistor (HBT) HB20M technology process provided by UMS Foundry. Measurements show a relative tuning range of about 30%, an average sensitivity of about 83 MHz/V, a minimum output power of 11.4 dBm and a phase noise at 100 kHz of frequency offset from the carrier lower of −107 dBc/Hz.

Design of a Miniaturized On-Chip Bandpass Filter Using Edge-Coupled Resonators for Millimeter-Wave Applications

A unique miniaturization technique for on-chip passive device implemented in gallium arsenide (GaAs)-based technology is presented, which is based on edge-coupled cells (ECCs). The principle of an ECC is first studied by means of the equivalent LC circuits. Then, using the ECC as a baseline, a combination of different shorting-ground and tapping methods is fully investigated in terms of their impact on frequency responses. By directly shorting the specific edge-coupled fingers to the ground, an ECC can be converted into a resonator without increasing any physical size. To further demonstrate the feasibility of using this technique for miniaturized monolithic microwave integrated circuit design, an on-chip bandpass filter (BPF) is implemented and fabricated in a commercial 0.1- $\mu \text{m}$ GaAs technology. The measurement results show that the 3-dB bandwidth of the filter is from 21.2 to 26.5 GHz, while the insertion loss is less than 2.9 dB at 23 GHz. In addition, more than 30 dB of suppression is achieved from 0 to 15 GHz and from 44 to 54 GHz. The size of the BPF is only $ {640} \times {280}~\mu \text{m}^{{2}}$ , excluding the pads, which is equivalent to ${0.17} \times {0.08} \lambda _{g}^{{2}}$ . ( $\lambda _{g}$ is the guided wavelength at 23.5 GHz.)

A Novel 4-D Artificial-Neural-Network-Based Hybrid Large-Signal Model of GaAs pHEMTs

A novel hybrid large-signal model of GaAs pseudomorphic HEMTs (pHEMTs) is proposed for monolithic microwave integrated circuit design. This new model is based upon accurate electromagnetic (EM) description and creative multi-path artificial neural network (ANN) optimization. To precisely describe the EM effect in the high-frequency range, the extrinsic part of this model includes both lumped and distributed components. In order to re-grid the discrete data, the bias-dependent intrinsic elements are determined by ANNs rather than traditional interpolations. The dispersion effect is represented by nonlinear sources with the multi-path-dependent integration technique, which is described by processed multi-bias S-parameters. This proposed approach can be applicable to different bias conditions, which is also verified by different types of GaAs pHEMTs with good agreement. In addition, a class-AB Ka-band power amplifier and a Ka-band switch using a 0.15- $\mu {\text {m}}$ GaAs pHEMT process were designed based on the novel hybrid model for further practical verification.

결합 접지면 구조의 사각 분리형 링 공진기의 등가 653회로 모델링 해석

In this paper, the Square Split Ring Resonator(: SRR) of Defected Ground Structure(: DGS), applicable to MMIC(: Monolithic Microwave Integrated Circuit) design, is proposed. The mathematical method to solve the equivalent parameter of the resonator from the measured results of resonator is introduced in this paper. To verify the method, SRR-DGS resonator with 2.95 GHz center frequency is fabricated, for measuring characteristics and calculating the equivalent parameter. The result from this process is compared with the data of the ADS simulation, and as a result both were identical.

A $W$-Band On-Wafer Active Load–Pull System Based on Down-Conversion Techniques

A new W-band active load-pull system is presented. It is the first load-pull system to implement a 94 GHz load by means of an active loop exploiting frequency conversion techniques. The active loop configuration demonstrates a number of advantages that overcome the typical limitations of W-band passive tuners or conventional active open-loop techniques in a cost-effective way: load reflection coefficients Γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> as high as 0.95 in magnitude can be achieved at 94 GHz, thus providing a nearly full coverage of the Smith chart. Possible applications of the setup include technology assessment, large-signal device model verification at sub-terahertz frequencies, and W-band monolithic microwave integrated circuit design and characterization. The availability of direct and accurate load-pull measurements at W-band should prove an asset in the development of sub-terahertz integrated circuits. First measurements performed on high-performance InP double heterojunction bipolar transistors and GaN high electron-mobility transistors are presented.

5GHz MMIC LNA Design Using Particle Swarm Optimization

This research presents an optimization study of a 5 GHz Monolithic Microwave Integrated Circuit (MMIC) design using Particle Swarm Optimization (PSO). MMIC Low Noise Amplifier (LNA) is a type of integrated circuit device used to capture signal operating in the microwave frequency. This project consists of two stages: implementation of PSO using MATLAB and simulation of MMIC design using Advanced Design System (ADS). PSO model that mimics the biological swarm behavior is developed to optimize the MMIC design variables in order to achieve the required circuit performance and specifications such as power gain, noise figure, drain current and circuit stability factor. Simulation results show that the proposed MMIC design fulfills the circuit stability factor and achieves a power gain of 19.73dB, a noise figure of 1.15 dB and a current of 0.0467A.

Study On The Improvement Of Bandwidth Of A Rectangular Microstrip Patch Antenna

Microstrip antennas or patch antennas are popular for their attractive features such as low profile, low weight, low cost, ease of fabrication and integration with RF devices. Micro strip antennas have been found favorable because they are inexpensive to manufacture and compatible with monolithic microwave integrated circuit designs (MMIC). They are usually employed at UHF and higher frequencies because the size of the antenna is directly tied to the wavelength at the resonance frequency. A Microstrip or patch antenna is a narrowband, wide-beam antenna fabricated by etching the antenna element pattern in metal trace bonded to an insulating dielectric substrate with a continuous metal layer bonded to the opposite side of the substrate which forms a ground plane. The most commonly employed microstrip antenna is a rectangular patch. The major disadvantages of Microstrip antennas are lower gain and very narrow bandwidth. Microstrip patch antennas have some drawbacks of low efficiency, narrow bandwidth (3-6%) of the central frequency. Millimeter wave technology being an emerging area is still much undeveloped. As micro strip antennas have found wide variety of application areas, a number of techniques are evolved to improve its limited bandwidth. A good approach to improve the bandwidth is increasing the thickness of substrate supporting the micro strip patch. However problems exist on the ability to effectively feed the patch on a thick substrate and the radiation efficiency can degrade with increasing substrate thickness. A substantial research needs to be done in this area as its applications are numerous. The radiation patterns and S11 performance are used for the analysis of the different configurations. In the present endeavor a rectangular patch antenna is designed on thick substrate and simulated using MATLAB software and configuration on different dielectric susbstrates was used .

Low-Power Very Low-Noise Cryogenic SiGe IF Amplifiers for Terahertz Mixer Receivers

State-of-the-art radio astronomy terahertz receivers utilize clusters of super-conducting mixers with cryogenic IF amplifiers. The critical parameters of the IF amplifiers are noise temperature, bandwidth, power consumption, input return loss, and physical size. This paper presents test data on three approaches to the IF amplifier; two are silicon-germanium (SiGe) monolithic microwave integrated circuit designs and the third is a discrete SiGe transistor miniature module. The amplifiers provide noise temperatures in the range of 5-15 K, from 1 to 6 GHz, at power consumptions as low as 2 mW.

New Thermocouple-Based Microwave/Millimeter-Wave Power Sensor MMIC Techniques in GaAs

We describe a new RF and microwave power sensor monolithic microwave integrated circuit design. The circuit incorporates a number of advances over existing designs. These include a III-V epitaxial structure optimized for sensitivity, the figure-of-merit applicable to the optimization, a mechanism for in-built detection of load ageing and damage to extend calibration intervals, and a novel symmetrical structure to linearize the high-power end of the scale.

Design of a KA-Band Image Rejection Sub-Harmonic Down-Converter MMIC

A Ka band image rejection sub-harmonic down-converter monolithic microwave integrated circuit (MMIC) is proposed. It contains a radio frequency (RF) amplifier, a broadband Lange coupler and two balanced mixers with two compact Marchand Baluns. The converter is fabricated by a commercial GaAs 0.2 μm pseudomorphic high electron mobility transistor (pHEMT) process, the size of which is 1.5 mm × 2 mm. Moreover, an improved nonlinear stability analysis method is presented in this paper. Based on the auxiliary generator (AG) technology, the method can analyze the nonlinear stability of circuits under the terminal impedance mismatched condition by setting the terminal load impedances as optimized variables. This method is applied to the sub-harmonic down-converter and is validated by the simulation and experiment. Experimental results show that from 30 GHz to 40 GHz, the conversion loss (CL) of the converter is less than 10 dB, and the image refection ratio (IMRR) is more than 15 dB.

Incorporation of BCB into Wafer-Scale Assembly MMIC's

Northrop Grumman Aerospace Systems (NGAS) has developed a Wafer Scale Assembly (WSA) process that is compatible with Benzocyclobutene (BCB) processes. BCB is a common dielectric material used to construct multi-metal interconnects. BCB processes enable additional metallization layers to be available for circuits and signal routing. WSA is a technology that physically bonds two or more wafers together to create a hermetically packaged MMIC (Monolithic Microwave Integrated Circuit). Two additional BCB layers, translates to two additional metallizations added to each side of the WSA, increasing the number of interconnect layers on both sides. Combining BCB and WSA processes has several benefits, including but not limited to: added MMIC design flexibility, MMIC size reduction, and ability to create three-dimensional passive structures. In this paper, results from NGAS' development on the WSA-BCB integration are presented, and key process considerations are discussed.

Accurate EM-Based Modeling of Cascode FETs

Cascode field-effect transistors (FETs) are widely used in the design of monolithic microwave integrated circuits (MMICs), owing to their almost unilateral and broadband behavior. However, since a dedicated model of the cell is rarely provided by foundries, a suboptimal description built by replicating the standard foundry model for both the common source and common gate device is often adopted. This might limit the success of the MMIC design at the first foundry run. This paper describes an electromagnetic-based empirical model of cascode cells, covering topics from the formulation and identification procedures to the corresponding validation described in an exhaustive experimental section. A MMIC low-noise distributed amplifier case is then presented and the proposed model is used for circuit analysis and instability detection. Clear indication is provided about the improvement in the prediction of critical behaviors with respect to conventional modeling approaches. A cascode cell with a symmetric layout is also successfully modeled.

New Formulas to Determine the Model for Spiral Inductors on GaAs

Generic and process-independent equivalent circuit model for simulating the performance of spiral inductor used in monolithic microwave integrated circuit design on gallium-arsenide substrate is presented. New formulas for the series inductor and feedback capacitor are presented. The experimental verification shows the proposed scalable model can be used as the prediction and optimization of spiral inductor performance.

A Novel Approach to Modeling Metal–Insulator–Metal Capacitors Over Vias With Significant Electrical Length

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In monolithic-microwave integrated-circuit design, a metalinsulatormetal (MIM) capacitor is one of the key passive components. Some commonly used MIM capacitor models are optimized for series capacitor applications. These conventional models, however, face a challenge as a need for a shunt capacitor application arises. This paper is a solution provider, ushering in a new approach to modeling a shunt capacitor of large electrical length over grounding substrate vias. Our model is derived from a set of design equations that allows asymmetric coupled lines in an inhomogeneous medium to be approximated to symmetric coupled lines in a homogeneous medium. Here we gain a theoretical insight into the rationale behind this approximation. The new approach benefits from: 1) a four-port implementation providing two connections to top and bottom plates and 2) a drastic reduction in mathematical complexity without trading off accuracy or compatibility. Circuit and electromagnetic simulations has proven to be in good agreement with measurements of a test structure of electrical length 558$^{\circ}$ at 50 GHz. </para>