Search

Single-ended and balanced 90–120 GHz microstrip power amplifier MMICs have been designed for cost-sensitive 5G and 6G backhaul in a commercial 6-inch, 0.1-µm GaAs process. At 108 GHz, measured output power is 20.4 and 22.5 dBm, respectively. At 120 GHz, measured output is 12.6 and 17.4 dBm, respectively. This is the highest reported for GaAs, among the highest reported to date for microstrip MMIC amplifiers at these frequencies and competitive with more expensive InP and GaN processes. Measurement is compared with simulation. [ABSTRACT FROM AUTHOR]

With the advent of 5G, software-defined radios (SDRs), and ultra-wideband systems, there is a rapid rise in the demand for reconfigurable RF front ends. Conventional methods of using filter banks or cascading multiple devices to achieve wideband performance would result in bulky hardware. Devices that can change their characteristics and respond in a controlled manner to a desired input are suitable for such designs. In filtering applications, the most desirable adaptive features include band-switching capabilities, the use of a cutoff frequency and/or bandwidth tuning, and a change in filter response from passband to stopband. Periodic structures have demonstrated great potential in achieving these characteristics. [ABSTRACT FROM AUTHOR]

The temperature-dependent thermal conductivities of a GaAs pseudomorphic high-electron mobility transistor’s (pHEMT) substrate and epilayer regions are extracted to develop a 3-D finite-element-method thermal model. The thermal characterization is based on electrical gate-metal-finger temperature measurements of a customized GaAs pHEMT test structure. Heat flow from an integrated thin-film resistor is shown to be sensitive to the device’s substrate thermal conductivity, while heat flow from the device’s channel is most significantly affected by the epilayer region thermal conductivity. These observations are used in the formulation of the thermal parameter extraction technique, which serves as a useful and convenient device modeling tool that can be integrated into an engineering design flow. Specific knowledge about the semiconductor material fabrication process, which may be unavailable to the design engineer, is not required for accurate thermal characterization; this is the overriding advantage of the technique presented. [ABSTRACT FROM PUBLISHER]

The thermal impact of device bias-state and structures (such as source connected field plates, gate-pitch, back-vias, and number of gate fingers) in AlGaN/GaN-on-Si high electron mobility transistors (HEMTs) are measured using gate metal resistance thermometry (GMRT). The technique characterizes the thermal response of device gate metallization to determine the gate-epilayer junction temperature (Tj) , which is directly influenced by the channel heat source due to its close proximity. It is found that low gate leakage levels in GaN HEMTs make them favorable candidates for GMRT. Bias-dependent self-heating, independent of power dissipation, is observed in the devices. Therefore, Tj of different device configurations are compared at constant bias state, as well as constant power density (3.75 W/mm) to improve accuracy. Tj reduction is observed at high drain bias due to the migration of the channel heat source toward the gate field plate edge. This provides independent experimental validation for a reported electrothermal model [7]. A 3-D thermal finite element method model is presented, which simulates measured Tj rise to within \sim6\% across a range of device configurations and operating conditions. This is ultimately made possible upon implementation of a thermal boundary resistance layer and extraction of its temperature response using GMRT data. [ABSTRACT FROM PUBLISHER]

Gate junction temperature is presented as the crucial parameter for modeling thermal degradation in GaAs device reliability studies, and sufficient for modeling the impact of temperature on device terminal characteristics. Gate metal resistance thermometry (GMRT) is applied to a GaAs pseudomorphic high-electron mobility transistor to measure its gate junction temperature. It is found that gate leakage current due to impact ionization can interfere with dc GMRT measurements. To the best of our knowledge, for the first time it is demonstrated that this can be largely avoided by instead applying an ac version of GMRT. However, the dynamic resistance of the gate leakage current path can interfere with ac GMRT. Measurements and thermal finite element method simulations of devices at constant power dissipation conclude that the bias dependence of the channel heat source profile affects the gate junction temperature. A parameter extraction technique is presented and used in device lifetime calculations to demonstrate MTTF variations of more than an order of magnitude (despite fixed power) due to bias-dependent self-heating. [ABSTRACT FROM AUTHOR]

Thermal-impedance models of single-finger and multifinger InGaP/GaAs heterojunction bipolar transistors (HBTs) are extracted from low-frequency S-parameters that are measured on wafer and at room-temperature, and from temperature-controlled dc measurements. Low-frequency S-parameters at room temperature are accurate for extracting thermal corner frequencies. However, the dc value of the thermal impedance depends on the emitter resistance and the dc current definitions of the HBT model; hence, they need to be extracted together from temperature-dependent dc measurements. The resulting thermal-impedance model explains the low-frequency dispersion well at varying bias conditions, and it is suitable for nonlinear circuit analysis. [ABSTRACT FROM AUTHOR]

A new technique is proposed for the design of linear power amplifiers at millimeter-wave frequencies where load-pull of large transistor output cells is difficult. The technique transforms the load-pull data on a small, standard foundry transistor layout to a pair of common-gate contours for the intrinsic device; one source–gate and one drain–gate. These are recombined as an intrinsic drain–source contour for a larger and arbitrary transistor layout. A Q-band driver amplifier for the ETSI 42-GHz point-to-point radio band has been designed using the proposed technique. The fabricated MMIC consumes 1 W and has a gain of 21 dB, with OIP3 of 35 dBm, OIP5 of 28 dBm and P1 dB of 23 dBm. The PAE is approximately 19%. The OIP3 to P1 dB and OIP3 to dc power ratios are believed to be the best reported to date. [ABSTRACT FROM AUTHOR]

The architecture and design of broadband, highly integrated up- and down-converters in GaAs pHEMT technology is described. Two up-converters and two down-converters have been designed to reduce the complexity and cost of broadband millimeter-wave systems by integrating a number of functions into compact MMICs. Broadband performance was achieved for approximately 17-35 GHz (low band) and 30-45 GHz (high band) with up-conversion input-referred, third-order intercept point exceeding 12 and 10 dBm, respectively, with good 2 x local oscillator leakage and excellent gain control. To the best of the authors' knowledge, this is the highest level of integration achieved for up- and down-converters at these frequencies. [ABSTRACT FROM AUTHOR]

Examines the fabrication of wide-band monolithic-microwave integrated-circuit mixer/phase shifters. Presentation of mixers based on diode and resistive-high electron-mobility transistor nonlinear elements. Application of the diode-based Kowari mixers bandwidth; Relevance of the application of appropriate control voltages.

A prototype down-converting mixer MMIC based on planar Schottky diodes and a production version based on HEMT diodes are reported. Measurements with a 1--2-GHz i.f. indicate conversion losses of 8-11 and 10--14 dB, respectively, and image rejections > 20 dB. A HEMT-based mixer-amplifier MMIC with conversion gain of 3--8 dB and image rejection > 18 dB is also reported. Simulations agree well with these measurements. Image rejection is produced by an on-chip i.f. coupler. This is the first report, lo the authors' knowledge, of fully monolithic, image-reject downconverters of this type. [ABSTRACT FROM AUTHOR]