J.P. Starski

Low-loss compact Butler matrix for a microstrip antenna

This paper presents the design and realization of a double four-port Butler matrix to feed a four-column array antenna with two orthogonally polarized signals (to obtain polarization diversity). The main goals of this study are the reduction of the size and the losses of the network. In order to meet those requirements, a bi-layer structure, the suspended stripline, has been adopted to support the circuit. Moreover, the complete network has been integrated in a single unit. The double four-port Butler matrix has been etched on both sides of the suspended substrate to solve the problem of the cross between the lines. The broadside suspended 3-dB directional coupler has been chosen for the design of the 3-dB hybrid coupler. In order to change the side of the suspended substrate, contactless transitions have been used. The network is designed to work within the range of frequencies of the GSM-900-MHz standard: band 880 MHz-960 MHz, center frequency f/sub 0/=920 MHz. Measured losses for a 4/spl times/4 Butler matrix are 0.3 dB.

Novel Schiffman phase shifters

In a standard Schiffman phase shifter a coupled section and a uniform transmission line are used to give a differential phase shift. In order to achieve larger bandwidth it is necessary to use tight coupled sections which are difficult to realize. It is shown how different configurations of coupled lines or parallel connected coupled lines can be used together with a uniform transmission line, other coupled lines, or parallel connected coupled lines in order to obtain a differential phase shifter with loose coupled lines and the same performance as for the standard case. The measurements confirm the calculated results, leading to a more realizable structure. >

Ultralow-Power Cryogenic InP HEMT With Minimum Noise Temperature of 1 K at 6 GHz

We present in this letter an InGaAs/InAlAs/InP high-electron-mobility transistor (InP HEMT) with record noise temperature at very low dc power dissipation. By minimizing parasitic contact and sheet resistances and the gate current, a 130-nm-gate-length InP HEMT was optimized for cryogenic low-noise operation. When integrated in a 4- to 8-GHz three-stage hybrid low-noise amplifier operating at 10 K, a noise temperature of 1.2 K ± 1.3 K at 5.2 GHz was measured. The gain of the amplifier across the entire band was 44 dB, consuming only 4.2 mW of dc power. The extracted minimum noise temperature of the InP HEMT was 1 K at 6 GHz.

Synthesis of Schiffman phase shifters

Formulas for the synthesis of Schiffman phase shifters are presented. The formulas make possible the calculation of the bandwidth and maximum phase deviation for a given coupling coefficient or the calculation of the coupling of the coupled section in order to obtain specified phase deviation or maximum bandwidth. Design curves for a 90 degrees Schiffman phase shifter are also presented. >

60 GHz Broadband MS-to-CPW Hot-Via Flip Chip Interconnects

In this letter, the microstrip-to-coplanar waveguide (MS-to-CPW) hot-via flip chip interconnect has been experimentally demonstrated to have broadband performance from dc to 67 GHz. The interconnect structures with the hot-via transitions were first designed and optimized by using the electromagnetic simulation tool. Three types of designs were investigated in this letter. The interconnect structures were then fabricated and radio frequency (RF) tested up to 67GHz. The optimized interconnect structure with the compensation design demonstrated excellent RF characteristics with the insertion loss less than 0.5dB and the return loss below 18dB over a very broad bandwidth from dc to 67GHz. This is to our knowledge the best result reported for this frequency range.

4-8 GHz Low Noise Amplifiers using metamorphic HEMT Technology

This paper describes two metamorphic high electron mobility transistor (mHEMT) amplifiers with low noise in the frequency band 4-8 GHz. One amplifier contains the complete circuitry on a monolithic microwave integrated circuit (MMIC) chip and the other is configured with the input network on a low loss duroid substate together with an MMIC. The measurements at room temperature for the MMIC gave a gain of 28plusmn1 dB and a typical noise temperature of 56 K. The measurements at room temperature for the hybrid-MMIC gave a gain of 29plusmn2 dB and a minimum noise temperature of 41 K. When cooled to 20 K the hybrid-MMIC obtained a minimum noise temperature of 6 K. The hybrid-MMIC is compared to InP based hybrid LNAs at cryogenic temperature

A broad-band differential phase shifter of novel design

A broad-band, multisection, differential phase shifter with excellent phase ripple has been designed. The phase shifter exhibits no more than a one degree error from nominal over more than a 90% bandwidth. The novel parallel connection of the coupled lines makes it feasible to realize the circuit using edge coupling.

Investigation of parylene-C on the performance of millimeter-wave circuits

Parylene-C is a polymeric material primarily used in hybrid manufacturing for humidity protection and dielectric isolation. In this study, the influence of Parylene-C on passive millimeter-wave circuits such as transmission lines and resonators is investigated in electromagnetic simulations up to 100 GHz and measurements up to 67 GHz. It is demonstrated that when applying 5-mum Parylene-C, the resonance frequency of a resonator is shifted 0.4% and the Q value is changed slightly. The dissipation factor of the Parylene-C versus frequency has been calculated from measured data. The flip-chip mounted broadband traveling-wave monolithic-microwave integrated-circuit (MMIC) amplifier is also investigated. A 5-mum-thick Parylene-C coat results in a total loss of 1.04 dB. A positive side effect of the Parylene-C is that it allows heat, dissipated in the amplifier, to spread over a larger area, consequently lowering the backside temperature of the flipped MMIC with as much as 10 degC. The results from this study demonstrate that, concerning the electrical performance, Parylene-C is very well suited as protective coating in millimeter-wave applications and can be used as an alternative to a hermetic package in the frequency range from dc to 67 GHz to reduce weight and cost

Cryogenic 0.5–13 GHz low noise amplifier with 3 K mid-band noise temperature

A 0.5–13 GHz cryogenic MMIC low-noise amplifier (LNA) was designed and fabricated using a 130 nm InP HEMT process. A packaged LNA has been measured at both 300 K and 15 K. At 300 K the measured minimum noise temperature was 48 K at 7 GHz. At 15 K the measured minimum noise temperature was 3 K at 7 GHz and below 7 K within the entire 0.5–13 GHz band. The gain was between 34 dB and 40 dB at 300 K and between 38 dB and 44 dB at 4 K.

Numerical investigation of vertical contactless transitions for multilayer RF circuits

This paper presents some concepts for contactless transitions between different planar transmission lines. These types of transitions are important for use in e.g. multilayer designs. Another important reason to avoid galvanic connections at RF is that they may generate passive intermodulation products (PIM), which can be a serious problem in multifrequency systems. The investigated transitions operate in the extended GSM 900 band (880-960 MHz).