Both branch-line and rat-race couplers are easily realized using planar circuit technology as they employ only transmission lines without additional components. However, as the electrical lengths of the transmission line elements are either 90/spl deg/ or 270/spl deg/, such couplers consume a significant amount of circuit area. This paper shows the development of branch-line and rat-race couplers that use artificial transmission lines (ATLs) in place of conventional transmission lines resulting in significant size reduction. As the ATLs are constructed entirely from microstriplines, the couplers are easily fabricated using conventional printed-circuit processes. The design formulas developed for the ATLs are explicit. Full-wave simulation and experimental results were used to confirm the design approach for hybrids operating at 1.8 GHz. The frequency response of the proposed hybrids is similar to conventional hybrids.

/pdf/compact-planar-microstripline-branch-line-and-rat-race-4w9wmoer09.pdf

Compact planar microstripline branch-line and rat-race couplers

The design and measured results of a single-substrate transceiver module suitable for 76-77-GHz pulsed-Doppler radar applications are presented. Emphasis on ease of manufacture and cost reduction of commercial millimeter-wave systems is employed throughout as a design parameter. The importance of using predictive modeling techniques in understanding the robustness of the circuit design is stressed. Manufacturing techniques that conform to standard high-volume assembly constraints have been used. The packaged transceiver module, including three waveguide ports and intermediate-frequency output, measures 20 mm/spl times/22 mm/spl times/8 mm. The circuit is implemented using discrete GaAs/AlGaAs pseudomorphic high electron mobility transistors (pHEMTs), GaAs Schottky diodes, and varactor diodes, as well as GaAs p-i-n and pHEMT monolithic microwave integrated circuits mounted on a low-cost 127-/spl mu/m-thick glass substrate. A novel microstrip-to-waveguide transition is described to transform the planar microstrip signal into the waveguide launch. The module is integrated with a quasi-optical antenna. The measured performance of both the component parts and the complete radar transceiver module is described.

/pdf/a-compact-manufacturable-76-77-ghz-radar-module-for-574850ygdh.pdf

A compact manufacturable 76-77-GHz radar module for commercial ACC applications

RF circuits exhibit several distinguishing characteristics that make them difficult to simulate using traditional SPICE transient analysis. The various extensions to the harmonic balance and shooting method simulation algorithms are able to exploit these characteristics to provide rapid and accurate simulation for these circuits. This paper is an overview of RF simulation beginning with the characteristics of RF circuits that distinguish them from traditional analog circuits. Harmonic balance and shooting methods are described along with several important extensions. The emphasis is on presenting the algorithms at a conceptual level to provide a basic understanding of the operation and capabilities of the algorithms. Finally, it is shown how these techniques are applied to make common RF measurements.

/pdf/introduction-to-rf-simulation-and-its-application-3kznaumgda.pdf

Introduction to RF simulation and its application

A comprehensive analysis of various techniques currently used for assessing microwave components' nonlinear distortion behavior is presented in this paper. The output of a third-order system subject to a two- or three-tone input is given, and then used as the comparison reference for studying the response to a general multitone or random excitation. Theoretical results thus obtained allowed the generalization of standard two-tone intermodulation (IMD) figures of merit, to multitone IMD ratio, multitone or noise adjacent channel power ratio, and noise power ratio (NPR). This approach proved that normal NPR tests produce optimistic results that can be as large as 7 dB when evaluating in-band co-channel power interference.

/pdf/on-the-use-of-multitone-techniques-for-assessing-rf-4sfml91qup.pdf

On the use of multitone techniques for assessing RF components' intermodulation distortion

In this paper, the intermodulation distortion (IMD) behavior of LDMOS transistors is treated. First, an analysis is performed to explain measured IMD characteristics in different classes of operation. It is shown that the turn-on region plays an important role in explaining measured IMD behavior, which may also give a clue to the excellent linearity of LDMOS transistors. Thereafter, with this knowledge, a new empirical large-signal model with improved capability of predicting IMD in LDMOS amplifiers is presented. The model is verified against various measurements at low as well as high frequency in a class-AB power amplifier circuit.

/pdf/prediction-of-imd-in-ldmos-transistor-amplifiers-using-a-new-2wzfrozcuy.pdf

Prediction of IMD in LDMOS transistor amplifiers using a new large-signal model

We present a general method for the generation of lumped element equivalent circuits for linear passive reciprocal distributed microwave components from time domain scattering signals. The method is based on a field theoretical analysis of the distributed multiport circuit in time domain. For this purpose the three-dimensional transmission-line-matrix method is used. A canonical representation of the multiport admittance matrix Y(p) allows one to extract an equivalent circuit directly after specifying the frequency range of validity. Topology as well as the parameters of the lumped element equivalent circuit are generated by the method. A distributed three-port microwave circuit was modeled and the applicability of the generated circuit model in transient SPICE simulations could be demonstrated.

http://ieeexplore.ieee.org/iel4/5942/15884/00738066.pdf

T. Mangold

Papers

Microwave circuits