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This paper demonstrates a practical approach to developing a geometrically scalable thermal resistance model to optimize layout for improved electrical performance of high-power RF transistors. The model is developed using finite element-based simulations, which show very good agreement with measured results. The proposed modeling methodology precomputes simulations over all possible layout considerations...
Summary form only given. This work discusses the efficiency bandwidth constrains in Doherty amplifiers. An analysis of the bandwidth limitations imposed by the impedance inverter and output capacitance of the active devices is given. Alternative wideband matching and output connection schemes for Doherty amplifiers are evaluated for their efficiency performance both at full output power, as well as,...
A new optoelectronic oscillator (OEO) topology based on a class E analog fiber optic link is presented. This topology provides a high level of inherent opto-electronic conversion gain in the analog fiber optic link portion of the OEO thus eliminating the need for dedicated post-detector gain. The class E operation also allows for dual loop operation using a single optical detector and can provide...
A versatile scalable small signal model for high electron mobility transistors (HEMTs) of gate length 50 nm and 100 nm has been developed. The model covers a large bias range and includes the temperature dependence from 300 K to 15 K. Especially, it is capable to predict the noise behaviour of the transistor in dependence of ambient temperature and frequency.
Weather forecasting, hurricane tracking and atmospheric science applications depend on humidity sounding of atmosphere. Current instruments provide these measurements from ground based, airborne and LEO satellites by measuring radiometric temperature on the flanks of the 183 GHz water vapor line. We have developed miniature low noise receivers that will enable these measurements from a geostationary...
An efficient design procedure for directional couplers based on the effective even and odd mode characteristic impedances and electrical lengths is presented. These quantities which are extracted from the scattering parameters of the overall coupler structure allow for a systematic optimization. This is useful, for instance, when designing compensated high directivity couplers or when large bandwidth...
In this paper a new compact type of nanosecond high voltage pulse generator, developed for innovative medical treatments, which combines microstrip line technology and microchip laser triggered photoconductive semiconductor switches (PCSS), has been numerically characterized. Two different modeling methodologies have been considered. The first is based on a full wave finite difference time domain...
An accurate broadband surface integral equation formulation for interconnect-type problems is obtained from the volumetric integral equation. The three-dimensional volumetric current density inside the interconnect is expressed as a product of unknown vector surface current density at the conductor boundary times the known exponential factor describing the skin-effect attenuation of the current off...
This paper describes a new mixed time-frequency method especially conceived for the efficient simulation of nonlinear multirate RF circuits evidencing some heterogeneity. The proposed method splits the circuit into two subsets, and can be seen as a hybrid scheme combining the popular envelope transient harmonic balance (ETHB) technique with a purely time-marching engine. With this method, the hardest...
In this paper, a 220 GHz solid-state power amplifier (SSPA) module is presented. Eight-way on-chip power combining is used to achieve a saturated output power ≥ 50 mW over a 217.5 to 220 GHz bandwidth, representing a significant increase in SSPA output power at this frequency compared to prior state of the art. The amplifier MMIC is implemented in coplanar waveguide (CPW) technology and uses sub 50...
A microstrip line-to-circular waveguide transition is described which operates at a nominal design frequency of 77 GHz. In order to improve the transmission characteristics, an additional periodically structured shield is used. The transition is capable of exciting a dielectric rod antenna, thus enabling the realization of radar modules on a PCB substrate with a dielectric rod antenna interface.
The aerospace industry has successfully leveraged commercial personal communication RF components and manufacturing technology to reduce the cost of active phased array antennas at L- and S-Band. This paper presents a brief overview of the design considerations for developing low-cost phased array architectures and manufacturing technology.
We demonstrates an optimized design of a highly efficient 3-stage Doherty PA for the 802.16e Mobile world interoperability for microwave access(WiMAX) application at 2.655-GHz. The ‘3-stage’ Doherty PA is the most efficient architecture among the various Doherty PAs for a high peak to average power ratio(PAPR) signal. However, due to the low quiescent bias point of the peaking PA, it has an improper...
The higher frequency bands of the point-to-point infrastructure radio have been the hardest to convert to SMT package. This paper describes complete solution that covers 37–45GHz in 4 SMT packaged chips. Transmit consist of 2 chips, an up-converter/VGA with 20dB gain control and power amplifier that provides 38dBm OIP3. The receiver is a single chip down-converter with less than 4.9dB NF. The single...
A Doherty power amplifier designed for TD-SCDMA base station applications using a dual path two-stage IC with LDMOS technology has been demonstrated with excellent performance. The IC was fabricated using Freescale HV7IC technology and designed to cover both the 1.88–1.92 GHz and the 2.01–2.025 GHz TD-SCDMA bands. It delivers 70 W P3dB output power under CW signal. At 40 dBm output power or 8.5 dB...
A new generation of High Voltage Heterojunction Bipolar Transistor (HVHBT) technology was developed for base station high power amplifiers and multi-stage driver amplifiers. This is an improved version of previously reported InGaP/GaAs HBT capable of operating with supply voltages up to 32 V. Generation 2 HVHBT technology maintains the same high level of efficiency and compatibility with Digital Pre-Distortion...
Microwave active-circuit design at the semiconductor level has been proposed as a real alternative for addressing the linearity versus efficiency trade-off in wireless applications, mainly when the use of traditional system-level architectures may be prohibitive due to cost or complexity. A wide set of techniques are available from the control of the transistor physics to device-based implementations...
A highly-merged 2.4/5.7-GHz dual-band low-IF downconverter is demonstrated using 0.18-µm CMOS technology. Weaver and Hartley architectures are utilized to achieve high image-rejection ratio (IRR) of first and second image signals. The first LO (LO1) is set exactly halfway between the two bands. That is, the 2.4/5.7-GHz bands are the first image signal of each other. However, in a real home/commercial...
HBTs show much better performance compared to their BJT predecessors, but also require enhanced models for reliable circuit design. This talk addresses which enhancements are required and available in state-of-the-art models, namely, accounting for self-heating and bias-dependence of transit-time. Limitations of these models, and thus challenges for future modeling efforts, will also be addressed,...
Analysis of PIN diode's geometric effects on the performance of RF switches is presented with measured data. The impact of periphery-to-area ratio (P/A) is investigated in terms of forward bias resistance and linearity. Theoretical analysis shows the smaller periphery-to-area ratio of PIN diode can reduce not only the forward biased resistance, but also the power handling capability. In addition,...
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