Millimeter-wave Circuits Research Articles

A low-loss time-delay phase shifter controlled by piezoelectric transducer to perturb microstrip line

This paper presents a new time-delay phase shifter using a piezoelectric transducer (PET) on a microstrip line with computational and experimental results. Dielectric perturbation changes the line capacitance and propagation constant of the microstrip line. The phase of the microstrip line is varied, but insertion loss is not much affected. A maximum phase shift of 460/spl deg/ with respect to the unperturbed condition has been achieved with an increased insertion loss of less than 2 dB and a total loss of less than 4 dB up to 40 GHz, using the dielectric perturbation controlled by PET. The proposed phase shifter should have many applications in antenna beam steering and in other microwave and millimeter-wave circuits.

Reduction of common-source inductance in FET/HEMT structures utilizing wave-propagation effects

In this paper, a novel high-frequency/high-power field-effect-transistor structure is presented to reduce gain degradation caused by common-source inductance. In this structure, the reduction in common-source inductance is achieved without the need for using very thin substrates or very complicated fabrication technology, such as vias under each source finger. Using detailed transmission-line modeling, it is shown that a significant reduction in common-source inductance and improvement in RF performance can be achieved even for moderately high values of source grounding via inductance. The new structure allows simpler fabrication technology and is expected to be particularly useful to reduce the cost and improve the performance of high-power microwave and millimeter-wave devices and circuits.

Partially prism-gridded FDTD analysis for layered structures of transversely curved boundary

In this paper, a partially prism-gridded finite-difference time-domain (FDTD) method is proposed for the analysis of practical microwave and millimeter-wave planar circuits. The method is featured by hybridizing the flexible prism-based finite-element method to handle the region near the curved metallization boundary and the efficient rectangular-gridded FDTD method for most of the regular region. It can be used to deal with shielded or unshielded planar components such as patch antennas, filters, resonators, couplers, dividers, vias, and various transitions between planar transmission lines. Although only representative structures, e.g., grounded via, through hole via, and coplanar waveguide to coplanar stripline transition, are analyzed in this paper, the underlined formulation is applicable to layered structures with arbitrary curved boundary in the transverse direction. The accuracy of this method is verified by comparing the calculated results with those by other methods. Also, by the analysis of computational complexity, the present method is shown to be as efficient as the conventional FDTD method, with negligible overhead in memory and computation time for handling the curved boundary.

Development of Broadband Low Actuation Voltage RF MEM Switches

Low insertion loss, high isolation RF MEM switches have been thought of as one of the most attractive devices for space‐based reconfigurable antenna and integrated circuit applications. Many RF MEMS switch topologies have been reported and they all show superior RF characteristics compared to semiconductor‐based counterparts. At the University of Illinois, we developed state‐of‐the‐art broadband low‐voltage RF MEM switches using cantilever and hinged topologies. We demonstrated promising sub-10 volts operation for both switch topologies.The switches have an insertion loss of less than 0:1 dB, and an isolation of better than 25 dB over the frequency range from 0.25 to 40 GHz. The RF Model of the MEM switch was also established. The low voltage RF MEM switches will provide a solution for low voltage and highly linear switching methods for the next generation of broadband RF, microwave, and millimeter‐wave circuits.

A novel PBG structure for a microwave integrated circuit and a planar antenna in a telecommunication system.

Applications of the novel artificial microwave crystal, PBG, made by etching were demonstrated for the circuit as well as for the antenna. The PBG was designed using a computer program based on the FDTD method. From observation of experimental data, the improvement of the microwave and millimeter-wave circuit and of the planar antenna by combining the PBG technique were confirmed.

Suppression of leakage resonance in coplanar MMIC packages using a Si sub-mount layer

In this paper, we examined the parasitic leakage resonance of coplanar monolithic microwave and millimeter-wave integrated circuits (MMICs) by the finite-difference time-domain calculations and experiments. The results show that leakages from coplanar MMICs become significantly resonant in finite substrates and packaging enclosures. In order to avoid the leakage resonance, a resonance suppression method using a doped-Si sub-mount layer is proposed and experimented in a frequency range from 0.5 to 40 GHz. The resonance suppression scheme is verified by measuring the S-parameters of the fabricated conductor-backed coplanar waveguides having an Si sub-mount layer of different resistivities (1 m/spl Omega//spl middot/cm, 15 /spl Omega//spl middot/cm, and 4 k/spl Omega//spl middot/cm). The leakage resonance can be completely suppressed using the typical 15 /spl Omega//spl middot/cm Si sub-mount layer.

Silicon Micromachining for High Performance Passive Structures at W Band

This paper presents a micromachined technology allowing the realization of very high aspect ratio millimeter‐wave circuits. Appropriate 3D electromagnetic simulations based on the finite element method have been implemented to design the circuits. Coplanar transmission lines featuring loss level in the 2 dB range up to 105 GHz have been realized. An original silicon micromachined cavity using the whispering gallery modes properties has been realized achieving a quality factor close to 10,000 range at 95 GHz.

Capacitive transmission lines in coplanar waveguide for millimeter-wave integrated circuit design

For use in millimeter-wave integrated circuits, theoretical and experimental design data for various useful capacitive transmission lines in coplanar waveguide on gallium arsenide are presented. Multifinger and metal-insulator-metal (MIM) lines enabling low characteristic impedance of the order of 10 /spl Omega/ as well as broadband capacitive coupled transmission lines are investigated. Simple design rules and accurate models validated with measurements up to 120 GHz demonstrate that such planar transmission lines can be used in monolithic microwave integrated circuits (MMICs) to extend the impedance range and the design flexibility with respect to the conventional CPW.

Theoretical analysis and FDTD simulation of GaAs nonlinear transmission lines

The GaAs nonlinear transmission line (NLTL), a monolithic millimeter-wave integrated circuit consisting of a high-impedance transmission line loaded by reverse-biased Schottky diodes, is studied in detail in this paper. A distributed model of the NLTL is successfully developed through the use of the microwave network theory. This model is more accurate than the lumped-element model that has been widely used before. The application of the NLTL for picosecond pulse generation, including shock-wave formation, is explained in detail based on the distributed model. Finally, the finite-difference time-domain (FDTD) technique is used to simulate the NLTL's for the first time. The simulation results show good agreement with the experiment results, FDTD is more accurate than SPICE in the simulation of NLTL's.

Transient simulation of millimeter-wave circuits incorporating numerical device modeling

A fast convolution-based computational approach is employed to integrate numerical solid-state device simulation with nonlinear millimeter-wave circuit simulation. Unlike previous combined harmonic-balance/device approaches, the high-frequency circuit/physical device response is allowed to evolve in time to its natural steady-state mode of operation, permitting insight into harmonic and parametric energy exchange, stability, load pulling, and frequency tuning effects. To demonstrate this computationally efficient approach, a second-harmonic 150-GHz transferred electron oscillator is simulated using both conventional Gunn and novel stable-depletion-layer InP devices. The integrated device/circuit simulations in the time domain enable us to investigate the formation and buildup of the oscillation modes in detail.

Ka band micromachined dielectric resonator oscillator

A new design and realisation of high performance micromachined millimetre wave circuits on silicon is presented. Combining the excellent electrical performance of micromachined structures and whispering gallery mode properties, an original micromachined dielectric resonator oscillator (MDRO) has been realised which operates in the 35 GHz region.

Photoempfindliche Koplanarleitungen auf CdS-CdSe-Al2O3-Basis für optisch gesteuerte Mikro- und Millimeterwellenkomponenten

Article Photoempfindliche Koplanarleitungen auf CdS-CdSe-Al2O3-Basis für optisch gesteuerte Mikro- und Millimeterwellenkomponenten was published on March 1, 1999 in the journal Frequenz (volume 53, issue 3-4).

Full-wave electromagnetic simulation of millimeter-wave active devices and circuits

This paper discusses the most recent progress in developing effective physics-based models for devices operating at millimeter-wave frequencies. The model is based on coupling dynamic electromagnetic wave solutions with carrier transport models. The potentials of this modeling approach for both device simulation and the global simulation of millimeter-wave circuits are demonstrated. Results comparing the full-wave model developed with conventional electrostatic models are provided through the simulation of different microwave transistors. The ability of the model to detect traveling wave effects, such as phase mismatch between the input and output electrodes of a conventional transistor, and their effects on the device gain are also provided. Results from the simulation of an air-bridged gateMesfet, designed to reduce traveling wave effects in high frequency transistors and solve the problem associated with high gate resistance, are illustrated and discussed. Finally, results showing the ability of this technique to model the nonlinearity and the harmonic distortion are provided through the simulation of an amplifier circuit.

Extremely low-noise performance of GaAs MESFETs with wide-head T-shaped gate

Fully ion-implanted low-noise GaAs MESFETs with a 0.11-/spl mu/m Au/WSiN T-shaped gate have been successfully developed for applications in monolithic microwave and millimeter-wave integrated circuits (MMICs). In order to reduce the gate resistance, a wide Au gate head made of a first-level interconnect is employed. As the wide gate head results in parasitic capacitance, the relation between the gate head length (L/sub h/) and the device performance is examined. The gate resistance is also precisely calculated using the cold FET technique and Mahon and Anhold's method. A current gain cutoff frequency (f/sub T/) and a maximum stable gain (MSG) decrease monotonously as L/sub h/ increases on account of parasitic capacitance. However, the device with L/sub h/ of 1.0 /spl mu/m, which has lower gate resistance than 1.0 /spl Omega/, exhibits a noise figure of 0.78 dB with an associated gain of 8.7 dB at an operating frequency of 26 GHz. The measured noise figure is comparable to that of GaAs-based HEMT's.

A dedicated micromachining technology for high-aspect-ratio millimetre-wave circuits

This paper presents a new technological process to implement efficient millimetre-wave passive circuits on a silicon substrate. This process associates a thick positive photoresist acting as a mould for the realization of thick conductors (several microns) with an ultra-thin dielectric membrane using only two layers (SiO 2/Si 2N 3.8) in order to reduce both dielectric and ohmic losses in the coplanar millimetre-wave circuits. Coplanar transmission lines and a band-pass filter in the 30 GHz range, featuring respectively transmission losses lower than 0.2 and 1 dB, illustrate some potentialities of this process.

Si and SiGe millimeter-wave integrated circuits

Monolithic integrated millimeter-wave circuits based on silicon and SiGe are emerging as an attractive option in the field of millimeter-wave communications and millimeter-wave sensors. The combination of active devices with passive planar structures, including also antenna elements, allows single-chip realizations of complete millimeter-wave front-ends. This paper reviews the state-of-the-art silicon- and SiGe-based monolithic integrated millimeter-wave circuits. The technological background as well as active and nonlinear devices and passive circuit structures suitable for silicon- and SiGe-based monolithic integrated millimeter-wave circuits are discussed. Examples of such integrated circuits and first systems applications are also presented.

Multifunctional radar sensor for automotive application

A multifunctional radar system for vehicles consisting of two modules with a combined bistatic/monostatic arrangement is presented. One module acts as a transceiver, whereas the other is a receiving circuit. The transmitting part radiates a frequency-modulated signal alternately in two orthogonal polarizations. The receiving parts work with different local oscillator (LO) frequencies and detect both polarizations of the scattered signal simultaneously. From the resulting Doppler spectra and a distance measurement, the velocity, tilt angle, height with respect to ground, and the direction of the movement of a vehicle can be derived. From the polarimetric information, a classification of the road condition is possible. In a first approach, the sensor was built in a conventional waveguide technique. The second step was to realize the millimeter-wave circuits of both modules with monolithic silicon millimeter-wave integrated circuit (SIMMWIC) technology. To achieve a flat arrangement, a leaky-wave antenna is developed and coupled to the SIMMWIC's.

Matched absorbing medium techniques for full-wave tlm simulation of microwave and millimeter-wave components

This paper investigates the absorbing layer techniques for three-dimensional transmission-line matrix (3d-tlm) simulations. Applications are the full-wave analysis of structures such as microwave and millimeter-wave circuits open to free space. Two approaches are presented, namely the matched layer (ml) and the perfectly matched layer (pml) technique which is used for general cases. For the ml technique, which is efficient for matching guides operating in a quasi-TEM condition, a comparison of the different tlm condensed node is carried out. Concerning the more general case of the pml technique, the theoretical development of a new general three-dimensional (3d) tlm condensed cell is presented. Results pertaining to the characterization of planar circuits are compared with other solutions or measurements. It is found that a proposed unified approach, which includes the tlm simulation for matched layer media, yields very good performance in terms of the absorbing boundary condition (abc).

Circuit theory for spatially distributed microwave circuits

A spatially distributed radio-frequency (RF) circuit, microwave, or millimeter-wave circuit does not have a global reference node as required in conventional nodal analysis. Instead, local reference nodes associated with ports are required. This paper adapts modified nodal analysis to accommodate spatially distributed circuits, allowing conventional harmonic balance and transient simulators to be used.

A new uniplanar broad-band singly balanced diode mixer

A new type of completely uniplanar broad-band singly balanced diode mixer, which utilizes a coplanar waveguide (CPW) and slot line as the main transmission lines, is presented. With the radio frequency (RF) swept from 7.1 to 10.5 GHz and the local oscillator (LO) of 3.5 dBm at 7 GHz, the mixer exhibits a conversion loss from 6 to 10 dB. The LO-to-RF isolation is better than 20 dB, and the LO-to-intermediate frequency (IF) and RF-to-IF isolations are more than 36 dB. The mixer also exhibits good return losses at all three ports. It has several desirable features such as simplicity, wide bandwidth, good interport isolations, easy mounting of solid-state devices, and no via-hole ground connections. The uniplanar nature of this mixer makes it very suitable for low-cost microwave and millimeter-wave integrated circuits.