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Mixers are frequency conversion devices that are widely used in radio applications. This article presents an in-depth theoretical study on the parametric mixing and amplification performance of the time-varying transmission lines (TVTLs) and utilizes the concept to design two TVTL parametric mixers on a commercially available InGaP HBT process. Unlike traditional passive mixers, these parametric mixers can provide a mild conversion gain and achieve a relatively low-noise figure. For the traveling-wave TVTL, the theory of the parametric mixing with the single-sideband condition is reviewed and compared with the double-sideband mixing case. The noise performance analysis shows that the noise figure of the TVTL can be made arbitrarily low to the quantum noise limit through the input reactive termination. The theory serves as a guideline for the design of MMIC parametric mixers. Measurement results have shown that the MMIC traveling-wave TVTL can achieve a maximum of 2.1-dB conversion gain. The mean noise figure was 2.7 dB within the measured frequency band. For the reflective TVTL parametric mixer, the conversion gain and the pump power consumption can be significantly improved. The noise figure, however, is degraded due to the multiple reflections created in the matching circuit. These conclusions are supported by theoretical analyses, ADS harmonic balance simulations, and experiments in this article. [ABSTRACT FROM AUTHOR]

A stacked high-electron mobility transistor (HEMT) power amplifier (PA) has been designed and implemented in a commercial 0.1- \mu \textm InGaAs pHEMT process to increase gain and output power at millimeter-wave frequencies. The stability problem of the stacked HEMT has been analyzed. A new layout of the stacked HEMT for improving the high frequency stability is proposed and used in the PA design. Measurements on the three-stage PA with parallel devices verify the saturated output power of 25 dBm and the maximum power added efficiency of 15% at 61 GHz, which is the highest reported output power of stacked HEMT PAs. The chip size measures 3.2 mm2 which makes this the most power dense $V$ -band amplifier reported from GaAs with 100 mW/mm2. [ABSTRACT FROM PUBLISHER]

High-sensitivity super-regenerative receivers (SRXs) are demonstrated at 96 and 135 GHz, respectively, in this paper. They are based on high-Q quench-controlled metamaterial resonators with a differential transmission line loaded with a split-ring resonator (DTL-SRR) and a differential transmission line loaded with a complementary split-ring resonator (DTL-CSRR) in 65-nm CMOS. High-Q oscillatory amplifications are established by the sharp stopband introduced by metamaterial resonators. As such, high detection sensitivity is achieved for SRXs at millimeter-wave regions. The fabricated 96-GHz DTL-CSRR-based SRX has a compact core chip area of 0.014 mm2 with measured power consumption of 2.8 mW, sensitivity of -79 dBm, noise figure (NF) of 8.5 dB, and noise equivalent power (NEP) of 0.67 fW/√(Hz). The fabricated 135-GHz DTL-SRR-based SRX has a compact core chip area of 0.0085 mm2 with measured power consumption of 6.2 mW, sensitivity of -76.8 dBm, NF of 9.7 dB, and NEP of 0.9 fW/√(Hz). Compared to the conventional SRX with an LC-tank-based resonator at similar frequencies, the proposed SRXs have 2.8~4 dB sensitivity improvement and 60% smaller area. The integrated SRXs are also demonstrated for the imaging applications. [ABSTRACT FROM AUTHOR]

This paper addresses the limitations and difficulties, in terms of DC-current density restrictions, and process limitations, associated with implementing impedance inverters with high characteristic impedance for monolithic microwave integrated circuit (MMIC) Doherty power amplifiers (DPAs). It is theoretically shown that impedance inverters with high characteristic impedance can be realized by utilizing the output capacitance of the active devices, together with a compact Tee-network of transmission lines with feasible linewidths. The utility of the impedance inverter is proven by design and fabrication of a GaN MMIC-DPA for microwave link applications. Continuous wave (CW) measurements demonstrate a maximum output power of 35 \pm 0.5~dBm over a frequency range of 6.6–8.5 GHz. The power added efficiency (PAE) in 9 dB output power back-off (OPBO) is better than 30% in a frequency range of 6.7–7.8 GHz. Moreover, linearized modulated measurements, employing a 10 MHz 256-QAM signal with 7.8 dB peak to average power ratio (PAPR), demonstrate higher than 35% average PAE, with 27.5 \pm 0.2~dBm average output power, and an adjacent channel power ratio (ACPR) less than -45~dBc, across a 6.8–8.5 GHz frequency range. The fabricated chip-size measures 2.1~mm \times 1.5~mm. [ABSTRACT FROM AUTHOR]

A Doherty power amplifier for IEEE 802.16e mobile worldwide interoperability for microwave access (m-WiMAX) is fully integrated on a 1.2 \times 1.2~\ mm^2 die using a 2-\mu\ m InGaP/GaAs hetero-junction bipolar transistor (HBT) process. The direct input power dividing technique is employed on the chip. Broadband input and output matching techniques are used for broadband Doherty operation, and their effects are analyzed. A peaking amplifier 1.5 times larger than a carrier amplifier delivers high efficiency for m-WiMAX signal with a 9.6-dB crest factor and an 8.75-MHz bandwidth (BW). The PA with a supply voltage of 3.4~V has an EVM of 2.3% and a PAE of 31.5% at an output power of 24.75 dBm as well as an operating frequency of 2.6 GHz. A PAE over 30.3% and an output power of greater than 24.6 dBm with an EVM less than 3.15% and a gain variation of 0.2 dB are achieved across 2.5–2.7 GHz without any assisting linearization technique. After compensating AM-AM and AM-PM nonlinearity using a digital feedback predistortion algorithm, the PA exhibits a PAE of over 27% and an output power of over 23.6 dBm across 2.2–2.8~GHz while maintaining an EVM below 2.7%. [ABSTRACT FROM AUTHOR]

A 44-GHz monolithic microwave integrated circuit (MMIC) low-loss built-in linearizer using a shunt cold-mode high-electron mobility transistor (HEMT), based on the predistortion techniques, is presented in this paper. The proposed cold-mode HEMT linearizer can enhance the linearity of the power amplifier (PA) with a low insertion loss (IL<2 dB), a compact die-size, and no additional dc power consumption. These advantages make the linearizer more suitable for millimeter-wave (MMW) applications. The physical mechanism of the gain expansion characteristics of the proposed linearizer is analyzed. A systematic design procedure for a low-loss linearizer is developed, which includes: 1) insertion loss minimization through a device-size selection and 2) linearity optimization through a two-tone test. To demonstrate the general usefulness of the proposed linearizer, the linearizer was applied to a two-stage 44-GHz MMIC medium PA and a commercial MMW PA module. After linearization, the output spectrum regrowth is suppressed by 7-9 dB. To keep the adjacent channel power ratio below -40 dBc, the output power has been doubled from 15 to 18 dBm at 44 GHz. The error vector magnitude of the 16-quadrature amplitude modulation signal can be reduced from 6.11% to 3.87% after linearization. To the best of our knowledge, this is the first multistage MMW PA with a low-loss built-in linearizer [ABSTRACT FROM PUBLISHER]

We report a low conversion loss and high local oscillator (LO)-to-RF isolation 94-GHz monolithic-microwave integrated-circuit (MMIC) active down converter using 0.1-mum InGaAs/InAlAs/GaAs metamorphic high electron-mobility transistor (MHEMT). The fabricated MMIC active down converter employs a one-stage MHEMT amplifier in the RF port of the active down converter, thereby amplifying the RF signal and improving the LO-to-RF isolation by using an inherent S12 isolation characteristic. The fabricated MMIC active down converter shows an excellent conversion loss of 6.7 dB at an LO power of 10 dBm and high LO-to-RF isolations of 21 plusmn 0.5 dB in a frequency range from 93.7 to 94.3 GHz. High dc and RF performances of the MHEMT used for the active down converter are due to the optimized epitaxial and device structure, and a maximum transconductance of 760 mS/mm, a current gain cutoff frequency of 195 GHz, and a maximum oscillation frequency of 391 GHz were measured. A active down-converter module is assembled by mounting the active down-converter chip on a jig with low-loss transition structure between the coplanar waveguide and waveguide. The fabricated active down-converter module shows a good conversion loss of 10.9 dB and a very high LO-to-RF isolation of 27.5 dB at 94.03 GHz [ABSTRACT FROM PUBLISHER]

This paper describes a new low-pass filter topology based on tapered periodic structures. These filters exhibit interesting characteristics in terms of compactness, return loss, insertion loss, selectivity, and the suppression of spurious frequency bands. Hybrid prototypes with a 1-GHz cutoff frequency, based on a coplanar-waveguide technology, and using both low-cost and high-performance substrates, have been fabricated and measured. Spurious frequency bands can be suppressed to below -22 dB at frequencies up to 20 GHz. Passband ripples are negligible, and the return loss is better than 20 dB. A two-section filter has a length of 0.2 lambda and exhibits a -120-dB/dec selectivity, while a six-section filter is 0.51 lambda long and has a -560-dB/dec selectivity. A design procedure has been established. These filters are compatible with monolithic microwave integrated circuit technologies in which the capacitors can be realized as metal-insulator-metal structures [ABSTRACT FROM PUBLISHER]

A new approach to the modeling of frequency dispersion effects encountered in the drain current characteristics of state-of-the-art hetero field-effect transistors is presented. The empirical, equivalent-circuit based model is dedicated to efficient microwave circuit design and allows for the inclusion of individual dispersion effects, taking into account their respective time constants. The proposed topology allows for small- and large-signal analysis in both the time and frequency domains. Parameter extraction and verification of the model is carried out using pulsed-I-V and dc measurements as well as microwave frequency S-parameter characterization of both a GaAs pseudomorphic high electron mobility transistor (pHEMT) and an InP pHEMT technology. Finally, the model is employed in the design and realization of a GaAs pHEMT traveling-wave monolithic microwave integrated circuit. Simulation results are compared to measurements with a focus on figures of merit which are affected by frequency dispersion [ABSTRACT FROM PUBLISHER]

Impulse-radio (IR)-based ultra-wideband (UWB) technology is a strong candidate for short-range data communication and positioning systems. This paper examines the performance of time-of-arrival (TOA) position estimation techniques as well as the simulated and measured performances of an IR-UWB noncoherent energy-collection receiver. The noncoherent IR-UWB transceiver has been designed for operation over the frequency range 3.1-4.1 GHz and implemented in 0.35-μm SiGe BiCMOS technology. The performance of two different algorithms, namely, the threshold-crossing and the maximum selection (MAX) algorithms, are compared in terms of TOA estimation error in Saleh Valenzuela channel model 3 and channel model 4. The implemented structure of the TOA MAX algorithm suitable for IR-UWB-based noncoherent receivers is presented. A UWB testbed has been constructed in order to test and measure the transmitted waveform as well the receiver performances. The simulated receiver noise figure is 7.3 dB while the receiver gain is 34 dB. The TOA MAX algorithm can achieve ±5-ns positioning accuracy for 95% of cases. Constant transconductance tuning circuits for improved TOA estimation reliability are also presented. [ABSTRACT FROM PUBLISHER]

A comparison of single-pole single-throw switch topologies is presented in this paper. A three-MESFET monolithic GaAs switch was designed, for 2-GHz operation, fabricated and tested in three different bias conditions: Vbias = 0 (self-bias); Ibias = 0 (floating); and Vbias ≠ 0, Ibias ≠ 0 (biased). It will be shown that a floating configuration presents on-state lower insertion loss (IL) (~1.7 dB). However, the off-state isolation has the same order of magnitude in all three bias conditions (typically 50 dB). Comparing measurements and simulations, the best available nonlinear model for the floating bias operation was selected. Finally, several resonant topologies were studied and a new topology is proposed to increase the off-state isolation without degrading the on-state IL. The advantages and drawbacks of resonant topologies over nonresonant configurations are also discussed, taking into account technology constraints and operation frequency. A solution to reduce the inductor value is proposed [ABSTRACT FROM PUBLISHER]

Millimeter-wave signals are typically generated by frequency multiplication in modern single-chip or multichip module (MCM) systems. Consequently, the multiplication efficiency, spurious rejection, and size of the frequency multiplier ultimately limit the integration level and cost of these systems. This paper points to the size reduction of millimeter-wave frequency doublers by evaluating artificial transmission lines (ATL's) as a means to minimize the size of the low-impedance shunt stubs. As a result, we developed a 40-GHz frequency doubler, which used only 0.6-mm2 area on a monolithic microwave integrated circuit. Despite the area minimization, the doubler exhibited state-of-the-art conversion loss of 1 dB over 10% bandwidth and rejected the fundamental frequency signal by more than 20 dB over 25% bandwidth. Reported herein is the novel simulation of the frequency doubler with active harmonic loads. Included in this paper are theoretical evaluation and simulation of ATL's with models for lumped components and verification of the results by electromagnetic simulation. Due to the high efficiency, low area requirement, and over 20-dB rejection of the fundamental signal, this miniaturized ATL frequency doubler can be used as a building block in the generation of local-oscillator signals in single-chip and MCM millimeter-wave systems [ABSTRACT FROM PUBLISHER]

The method of moments (MoM) continues to be the most frequently used full-wave electromagnetic simulation technique for application to CAD and optimization of microwave circuits. In this paper, we present an order-recursive variant of standard LU decomposition for the efficient solution of moderately large linear systems arising in the application of MoM to iterative design problems. In comparison with the existing solution methods suitable for matrices of size such that direct resolution of the linear systems by Gaussian elimination or LU decomposition becomes feasible, the proposed order-recursive MoM (ORMoM) allows a very large portion of repetitive computations (from scratch) at each design iteration to be avoided, leading to extremely efficient design cycles. Specifically, it is shown that ORMoM results in an order of magnitude reduction in the solution time for typical microwave design tasks. Therefore, this contribution is a major advance toward EM simulation-based CAD and optimization of microwave circuits. [ABSTRACT FROM AUTHOR]

A new eigenmode algorithm, based on the method of lines, is presented for full-wave analysis of real three-dimensional (3-D) MMIC elements. Finite conductor thickness, finite substrate, dielectric or ohmic losses are rigorously modeled. The analytical calculation In the direction of propagation enables the analysis of structures with very short or long interconnections between the single discontinuities. To demonstrate the generality of the proposed algorithm several completely different structures were analyzed. Examinations of the convergence were performed. Scattering parameters of filters and planar transmission line interconnects like air bridges, via holes and bead transitions were investigated. The calculated results agree very well with computed and measured results published in literature. [ABSTRACT FROM AUTHOR]

In this paper, the transition discontinuities of flip chip circuits are modeled and investigated using finite-difference time-domain (FDTD) method to predict the S-parameters of different packages. This includes transition between two coplanar lines on the chip and mother board and transition between two striplines in a package. The computed S-parameter of the flip chip package using the FDTD model are used to develop an equivalent circuit for the transition discontinuity over a wide frequency band. A general and accurate equivalent circuit model of the interconnect has been developed and presented. In this circuit model, a statistical analysis is used to compute the value of the circuit elements. Also, losses in the flip chip package are represented by a simple function versus frequency. These losses include substrate loss of the chip and the mother board due to excitation of surface wave and radiation loss due to the bump. Conductor and material substrate losses are not included in this circuit model. Good agreement has been obtained between the S-parameters of the FDTD model and the equivalent circuit model over a wide frequency band of up to 50 GHz. Furthermore, the effects of the bump dimensions on the equivalent circuit model has been also evaluated and presented. The results show important issues in the design of the flip chip interconnect. The bump dimensions can be used as impedance matching parameters to achieve minimum losses over a wide frequency band. The presented equivalent circuit model can be used in commercial circuit simulators to predict monolithic microwave/millimeter wave integrated circuit (MMIC) performance including the package. [ABSTRACT FROM AUTHOR]

A novel approach for accurate and efficient modeling of monolithic microwave/millimeter wave integrated circuit (MMIC) components by using electromagnetically trained artificial neural network (EM-ANN) software modules is presented. Full-wave EM analysis is employed to characterize MMIC components. Structures for simulation are chosen using design of experiments (DOE) methodology. EM-ANN models are then trained using physical parameters as inputs and S-parameters as outputs. Once trained, the EM-ANN models are inserted into a commercial microwave circuit simulator where they provide results approaching the accuracy of the EM simulation tool used for characterization of the MIMIC components without increasing the analysis time significantly. The proposed technique is capable of providing simulation models for MMIC components where models do not exist or are not accurate over the desired region of operation. The approach has been verified by developing models for microstrip vias and interconnects in dataset circuits. A new hybrid (/spl Delta/S) modeling approach which makes use of existing approximate models for components is introduced and shown to be a more efficient method for developing EM-ANN models. An example of using EM-ANN models to optimize the component geometry is included. [ABSTRACT FROM AUTHOR]

A combined finite-difference time-domain/matrix-pencil method is presented for the efficient and rigorous calculation of the full-wave modal S-parameters of waveguide components including structures of more general shape or high complexity. The application of the S-parameter definition for unmatched ports requires merely standard Mur's absorbing boundaries for reliable results, and a nonorthogonal or contour path mesh formulation allows the convenient inclusion of curved boundaries. The efficiency of the method is demonstrated for the analysis of waveguide and monolithic microwave/millimeter wave integrated circuit (MMIC) components of practical importance, such as the twisted waveguide, the twisted waveguide bend, the post compensated magic T, the waffle-iron filter, and the MMIC spiral inductor including an air bridge. The method is verified by excellent agreement with measurements, with finite element method (FEM) or moment method results. [ABSTRACT FROM AUTHOR]

Uniplanar coplanar waveguide (CPW), coplanar strip (CPS), and slotline on dielectric substrates have many applications in microwave integrated circuit (MIC) and monolithic microwave/millimeter wave integrated circuit (MMIC) designs. New power dividers using one-section and two-section coupled CPW have been developed. These circuits provide substantially improved performance over a wider bandwidth than conventional microstrip power dividers. Measured results show that the one-section CPW power divider has greater than 20-dB isolation, less than 0.3-dB insertion loss, a 0.2-dB power dividing imbalance, and a 20 phase imbalance over a bandwidth of more than 30% centered at 3 GHz. The two-section CPW power divider has greater than 24-dB isolation, less than 0.5-dB insertion loss, a 0.1 dB power dividing imbalance, and a 1.6/spl deg/ phase imbalance over a bandwidth of more than 66% centered at 3 GHz. Experimental results agree well with calculated ones. In-phase and 180/spl deg/ out-of-phase power dividers constructed by the circuit configuration method are described in this paper. The even-odd mode excited method is used to analyze the power dividers. Also two other power dividers using asymmetrical coplanar strip (ACPS) have been developed with good performance. A 180/spl deg/ out-of-phase power divider is demonstrated with an amplitude imbalance of 0.4 dB and a phase difference of 180/spl deg//spl plusmn/1/spl deg/ over a wide bandwidth. [ABSTRACT FROM AUTHOR]

A microwire technique has been developed for fabricating three-dimensional (3-D) structures for use in ultra-compact GaAs monolithic microwave/millimeter wave integrated circuits (MMIC). By folding metal into a U-shaped wall and burying it in a relatively thick polyimide insulator, vertical microwires can be made with greatly reduced process complexity. This technique also offers process compatibility with multilevel interconnects. In this paper, the fundamental characteristics of the proposed U-shaped microwire are discussed and its applications to 3-D passive elements and circuits are demonstrated. The characteristics of the U-shaped microwires are almost the same as those of I-shaped microwires and can be accurately estimated and designed by using numerical analysis. The fabricated and designed transmission lines are one-half to one-third the size of conventional lines with the same transmission loss, and if the microwire is also used as a shielding wall, the occupied area can be made much smaller. Miniature inductors made of vertical U-shaped microwires exhibit a self-resonance frequency as high as that of conventional inductors, with one-half the size and offer a great advantage in L- or S-band applications. A fabricated miniature wideband 3-D balun had an insertion loss of 1.5+1 dB at frequencies from 10 to 30 GHz, and an amplitude and phase balance of 2 dB and 5/spl deg/, respectively. [ABSTRACT FROM AUTHOR]