Antennas and waveguides for far-infrared integrated circuits

Antennas and waveguides for the wavelength range 0.1-3 mm are considered. Emphasis is placed on those designs which lend themselves to integration with each other and with other components such as diodes. The general properties of FIR antennas are reviewed. A novel silicon waveguide antenna is discussed, and its design, simulation, fabrication, and performance at 119 μm are described. This antenna has a highly symmetrical, single-lobed beam with 3 dB beamwidths of 35 and 38° in theE- andH-planes, respectively. The gain (measured in microwave simulation) is 12.8 dB. This antenna is well suited for integration with Schottky diodes. The related subject of FIR waveguides is discussed. Experiments with metal transmission lines at 119 μm are described and dielectric guides related to the waveguide antenna are also considered. Using components such as these it may soon be possible to construct receiver front ends for this wavelength range in integrated-circuit form.     

CAD techniques for microwave circuits

In little more than 10 years computer-aided design (CAD) of microwave circuits has moved from dumb terminals on mainframe computers to PCs, and now to powerful RISC workstations. Commercial CAD software now integrates the various stages of microwave circuit design: schematic capture, simulation and layout. This paper reviews the different CAD packages that are available for microwave circuit design. The basic principles employed in the modelling of microstrip circuits are introduced and the reasons for the extensive use of frequency-domain simulations are explored. The developments in nonlinear, electromagnetic and system-level simulation methods are described     

Statistical computer-aided design for microwave circuits

A useful methodology for microwave circuit design is presented. A statistical technique known as Design of Experiments is used in conjunction with computer-aided design (CAD) tools to obtain simple mathematical expressions for circuit responses. The response models can then be used to quantify response trade-offs, optimize designs, and minimize circuit variations. The use of this methodology puts the designer's intelligence back into design optimization while making “designing for circuit manufacturability” a more systematic and straightforward process. The method improves the design process, circuit performance, and manufacturability. Two design examples are presented in context to the new design methodology     

GaAs HBT's for microwave integrated circuits

The status of the microwave GaAs heterojunction bipolar transistor (HBT) technology is reviewed. Microwave circuits for advanced military and commercial systems continue to increase their dependence on the performance, functionality, and cost of active components fabricated using solid-state technology. The performance advantages provided by GaAs HBT's, for several critical circuit applications, have stimulated a worldwide development activity. Progress in HBT device technology and microwave circuit applications has been extremely rapid because of the broad availability of III-V compound semiconductor epitaxial materials and prior experience with GaAs field-effect transistors (FET's) and monolithic microwave integrated circuits (MMIC's). The great flexibility of HBT's in microwave circuits makes them prime candidates for applications in complex multifunctional microwave/digital IC's in next-generation systems     

Practical stability criterion for tunnel-diode circuits

A stability criterion for tunnel-diode circuits is described, which requires only plots of modulus of reflection coefficient versus frequency. The criterion is derived intuitively.     

Piezoelectric-transducer-controlled tunable microwave circuits

This paper introduces a new method to tune microwave circuits of phase shifters, filters, resonators, and oscillators, controlled by a piezoelectric transducer (PET) with computational and experimental results. An optimized PET-controlled phase shifter is demonstrated to operate up to 40 GHz with a maximum total loss of 4 dB and phase shift of 480°. PET-controlled tunable bandpass filter, ring resonator, and one-dimensional photonic-bandgap resonator show a very wide tuning bandwidth of 17.5%-28.5% near 10 GHz with little performance degradation. A new PET-controlled or voltage-controlled dielectric-resonator oscillator (DRO) is demonstrated with a tuning bandwidth of 3.7% at the center frequency of 11.78 GHz. The tuning bandwidth is slightly less than that of a mechanical tuning using a micrometer-head-controlled tunable DRO with a tuning bandwidth of 4.7%. The new tuning method should have many applications in monolithic and hybrid microwave integrated circuits     

GaAs integrated microwave circuits

GaAs has many desirable features that make it most useful for microwave and millimeter-wave integrated circuits. The process of selective epitaxial depositions of high purity single-crystal GaAs with various doping concentrations into semi-insulating GaAs substrates has been developed. These high-resistivity substrates (>10⁶ohm.cm) provide the electrical isolation between devices, eliminating the difficulties and deficiencies normally encountered in trying to obtain isolation with dielectrics, back-etching, p-n junctions, etc. This monolithic approach to integrated-circuits thus allows for improved microwave pedormance from the devices since parasitics are reduced to a minimum. Planar Gunn oscillators and Schottky barrier diodes have been fabricated for use in a completely monolithic integrated millimeter wave (94 GHz) receiving front end. The Gunn oscillators are made in a sandwich-type structure of three selective deposits whose carrier concentrations are approximately 10¹⁸-10¹⁵-10¹⁸cm^-3. The Schottky diodes consist of two deposits with concentrations of 10¹⁸and 10¹⁷cm^-3. The Schottky contact is formed by evaporating Mo-Au onto the 10¹⁷cm^-3deposits; all ohmic contacts are on the surface and are alloyed to the N⁺regions.     

Measurement techniques for monolithic microwave integrated circuits

Introduces the basic technologies that are associated with measurements of monolithic microwave integrated circuits. The use of test fixtures and wafer probe stations at ambient room temperature is reviewed and their role at thermal and cryogenic temperatures is discussed. With the increasing need for performing non-invasive measurements, advances in experimental field probing techniques are explored     

Uniplanar techniques for monolithic microwave integrated circuits

`Uniplanar' techniques have recently been introduced for the design of monolithic microwave integrated circuits (MMICs). The aim of these techniques is to achieve a higher level of integration of circuitry and to overcome the need for through-substrate via holes and the related back-face processing steps. This is achieved by using coplanar waveguide (CPW), slotline, and miniature `thin-film microstrip' transmission-line media as opposed to conventional microstrip. The design and performance of a number of uniplanar MMIC couplers, amplifiers, and other test circuits fabricated using the GEC-Marconi (Caswell) foundry are described     

Hybrid circuits for multioctave multiple-throw microwave switches

Single-pole multiple-throw microwave switches may be designed as extremely broad-band multistate low-pass filters. SPDT switch design using p-i-n diodes and high-impedance transmission line is described. Extension of the technique to multiple-throw switches is outlined. Two operating examples of the method, an 18-GHz bandwidth SPDT and a 12-GHz SP4T, are discussed.     

Modified suspended striplines for microwave integrated circuits

Suspended coupled striplines have very different even- and odd-mode phase velocities. A structure modified by the presence of a slot is proposed to obtain equalisation, a condition necessary to build broadband couplers. This modification has the advantage of preserving the suspended configuration.     

Circulators for microwave and millimeter-wave integrated circuits

The requirements for circulators for use in combination with microwave and millimeter-wave integrated circuits are reviewed, with special emphasis on modules for phased-array antennas. Recent advances in broadbanding and in miniaturization are summarized. Novel types of circulators that are fabricated by attaching a ferrite disc and a suitable coupling structure to the surface of a dielectric of semiconductor substrate (quasimonolithic integration) are described. Methods for achieving complete monolithic integration are also discussed     

Proton implantation isolation for microwave monolithic circuits

We show that proton implantation isolation effectively reduces RF losses for microwave monolithic integrated circuits and that the degree of effectiveness is a function of the induced damage depth. RF losses are mostly due to the current conduction in semiconducting active or buffer layer.     

Thin ferrite devices for microwave integrated circuits

This paper is intended as a review of developments which allow ferrite materials in a planar geometry to be used in the realization of magnetic devices which are compatible in form with other microwave integrated circuits. These devices include phase shifters (reciprocal and nonreciprocal), latching circulators, isolators, and phase and amplitude modulators. The application of some of these devices is demonstrated in the form of electronically steerable array antennas.     

Transmission characteristics of several kinds of closed groove waveguides for millimeter waves

An advantage of closed groove guide over open groove guide is attended. In this paper, the several kinds of closed groove guides including the trapezoidal-, elliptic- and parabolic-groove guides as new types of millimeter wave transmission lines are presented. Their dispersion and cut-off characteristics of the dominant mode are analysed and compared with ones of the closed V-and circular- groove guides by using the equivalent network method. The obtained results have important meaning in theoretical studies and actual applications of groove waveguides.     

Network analyses for transmission characteristics of several kinds of curve-shaped groove waveguides

In this paper, the several kinds of the novel curve-shaped groove guides including the whole elliptic-, whole cosine- and hyperbolic-groove guides as the new millimeter wave transmission lines are presented. The dispersion, cut-off and band characteristics of the dominant mode for the several kinds of the curve-shaped groove guides are analysed by using the equivalent network method with transverse resonance. The obtained results have important values in their theoretical studies and actual applications of the curve-shaped groove waveguides.     

Photovaractor for remote optical control of microwave circuits

A photovaractor for the remote optical control of microwave circuits was studied. The photovaractor was fabricated as a p-i-n photodiode placed in a pigtailed fiber optical module. The study of the impedance in the frequency range up to 3 GHz in darkness and under illumination has shown that the photovaractor capacitance strongly depends on the incident optical power. The capacitance variation of the photovaractor diode under illumination is discussed     

InGaAs microwave switch transistors for phase shifter circuits

A new InGaAs insulated-gate FET (IGFET) with 1 μm gate length and three different gate widths has been designed, fabricated and characterized as switch devices for microwave control applications in phase shifter circuits. The devices employed a plasma deposited silicon dioxide gate insulator and had multiple air bridged source regions. The details of the DC current-voltage (I-V) characteristics and small signal S-parameter measurements up to 20 GHz are presented. The switch IGFET's had a drain saturation current density of 300 mA/mm gate width with breakdown voltages of higher than 35 V. An insertion loss of 1.0, 0.6, and 0.4 dB at 10 GHz and 1.4, 0.8, and 0.4 dB at 20 GHz have been measured for the 300, 600, and 1200 μm gate width IGFET's, respectively. Equivalent circuit models fitted to the measured S-parameters for IGFET's yielded on-state resistances from 10.7 to 3.3 Ω, off-state resistances from 734.4 to 186.8 R and off-state capacitances from 0.084 to 0.3 pF as the gate width is increased from 300 to 1200 μm The simulation results using IGFET models for the phase shifter circuits indicated a maximum phase error of 0.11°, 0.26°, and 0.479 with 0.74, 0.96, and 1.49 dB maximum insertion loss and greater than 33, 26, and 19 dB return loss for the 11.25°, 22.5°, and 45° phase bits, respectively, over the 9.5-10.5 GHz frequency band     

Design of broadband microwave circuits

The relation between the scattering-matrix eigenvalue phase/frequency responses and the energy stored in a general microwave junction filled with an anisotropic material can be used to facilitate the design of broadband microwave circuits. The technique of this approach is illustrated for a waveguide Y-junction circulator.