Edgar Schmidhammer

Improvement of angular resolution of a millimeterwave imaging system by transmitter location multiplexing

Angular resolution and the angular width of the field of view are in the frame of autonomous intelligent cruise control (AICC) critical system parameters. A promising solution which avoids conventional phased array techniques is to use an array of receivers and the methods of digital beam forming in order to extract the complete 2D radar information. Angular resolution is in this case closely related to the number of receiving antennas respectively downconverters. A complete AICC systems working on these principles using four receivers has been built and published elsewhere. This paper shows that angular resolution can be improved at least by a factor of two without increasing the number of antennas and receivers by multiplexing the transmitter location. Two different configurations are compared. A very cost-effective way is to realize the necessary switching operations in the IF-band. Linear prediction algorithms are applied to fill the arising gap, leading to the full expected lateral resolution while maintaining sufficient side-lobe suppression.Angular resolution and the angular width of the field of view are in the frame of Autonomous Intelligent Cruise Control (AICC) critical system parameters. A promising solution which avoids conventional phased array techniques is to use an array of receivers and the methods of digital beam forming in order to extract the complete 2D radar information. Angular resolution is in this case closely related to the number of receiving antennas respectively downconverters. A complete AICC-system working on these principles using four receivers has been built and published elsewhere. This paper shows that angular resolution can be improved at least by a factor of two without increasing the number of antennas and receivers by multiplexing the transmitter location. Two different configurations are compared. A very cost-effective way is to realize the necessary switching operations in the IF-band. Linear prediction algorithms are applied to fill the arising gap, leading to the full expected lateral resolution transmit while maintaining sufficient side-lobe suppression.<<ETX>>

Appropriate Methods to Suppress Spurious FBAR Modes in Volume Production

Standards like CDMA in combination with the US PCS band impose challenging demands on the duplexer unit in the RF circuit of mobile phones. FBAR filters are candidates to fulfil the latest cutting-edge requirements for temperature stability, insertion loss, power durability, bandwidth, and filter skirts. Unfortunately, these filters suffer from spurious resonator modes. In this work we have investigated several suppression methods, which are capable of being applied to volume production

3.8 /spl times/ 3.8 mm/sup 2/ PCS-CDMA duplexer incorporating thin film resonator technology

Bulk acoustic wave (BAW) technology based on piezoelectric thin films has recently emerged as a preferred technology for the realization of miniaturized high performance RF filters and duplexers for wireless applications like mobile telephones. We present a duplexer for PCS-CDMA applications with a footprint of 3.8 mm /spl times/ 3.8 mm and a height of 1.1 mm. The duplexer consists of a transmit (TX) and a receive (RX) filter, both mounted as bare dies on a low temperature co-fired ceramic (LTCC) multilayer substrate incorporating additional matching elements. The filters are realized using solidly mounted resonator (SMR) technology, where an acoustic mirror separates the active resonator part from the substrate. Duplexer packaging is based on the EPCOS proprietary CSSP technology developed for the miniaturization of chip sized SAW packages including a cavity between the package and the acoustically active filter areas. The front-end technology for realizing the RF filters uses standard 200 mm CMOS technology and the deposition of AlN piezoelectric thin films with high thickness uniformity over the wafer. The duplexer is fully matched to 50 ohms with low insertion attenuation in the pass band, a superior stop band characteristic up to 10 GHz, and a temperature coefficient of frequency (TCF) of -20 ppm/K.

Baw components for PCS-CDMA applications

Bulk Acoustic Wave (BAW) technology is highly investigated due to its silicon-based technology for further integration in the RF part of e.g. mobile phones. This paper shows the current performance of various components suitable for the US PCS-CDMA band. In particular, new results of a duplexer are presented as well as new designs for a transmit filter and a receive filter. Besides the transfer functions, measurements of the temperature coefficient for left and right skirts are shown as well. The presented results show clearly our improvements within solidly-mounted-resonator (SMR) -BAW technology. Our process flow using a 200 mm manufacturing line uses only the minimum required process steps by still keeping a high yield in combination with high process stability and high process robustness.

Suppression of spurious modes in mirror-type thin film BAW resonators using an appropriate shape of the active area

F ilm bulk acoustic resonators (FBARs) have emerged as an important new technology for realization of GHz filter components. Two different technologies are commonly used: bridge-type and mirror-type resonator layer stacks. Both resonator configurations are susceptible to unwanted lateral modes beside the main resonance. Filters composed of FBARs, e.g. bandpass ladder-type filters, suffer from those spurious modes: they show a higher insertion loss, a lower bandwidth and several ripples in their passbands. Therefore, a practical method is needed to suppress spurious modes in FBARs. In the past, using membrane-type resonators with non-parallel edges of the active area (apodization) has been successfully applied to suppress lateral spurious modes. In contrast, for mirror-type FBARs the focus has been on mode suppression by means of a lateral edge design (frame-like resonators). In this paper we investigate in detail, if apodization works for acoustically more complicated mirror-type FBARs. We have processed a lot of eight 200-mm-wafers using a special test reticle set comprising resonators and filters with both distinct shapes of the active area, lateral edge design as well as combinations thereof. Our measurement results clearly single out optimum electrode shapes for apodization, but also manifest the superior performance of the lateral edge design. I. INTRODUCTION

Multiplexers: A necessary extension for 4G/5G systems

Carrier Aggregation is one prominent method to increase the data throughput in mobile communication. Dependent on the band combination to be realized (about 270 different band combinations are currently under discussion) either diplexers or multiplexers need to be used to realize suitable hardware. Whereas already today diplexers are applied for single-feed antenna concepts to separate e.g. the 1GHz from 2GHz bands, multiplexers are required for all those cases where filters and/or duplexers of bands close to each other need to be combined. Besides the pure electrical aspects like low insertion loss, high isolation to all active Rx-bands, steep skirts, high linearity, just to name a few, also mechanical aspects like area consumption and height need to be considered in order to address customer demands. All three items will be discussed shortly and underline the need for continuous improvement not only at the acoustic but also packaging side.

Novel quadplexer synthesis procedure

In this work a quadplexer (QPX) is designed by matching two duplexers (DPX) at 3GPP bands 3 and 7. The challenge in combining duplexers is the possibly high dimension of the optimization problem and the large number of candidate topologies. The authors discovered that antenna matching synthesis tool scope can be extended to multiplexer design to resolve the above challenges. The results reveal that an automated topology synthesis can identify redundancy in the matching circuit topology, and eventually lead to superior performance with less discrete matching elements provided by vendors. The synthesis can be carried out using vendor libraries, or, after proper topology identification, also using distributed elements. Tolerance analysis is readily available for determination of least sensitive matching circuit.

WSE: Advanced BAW-enabled wireless transceivers: From devices to system architecture

Bulk Acoustic Wave (BAW) resonators are now being used in functions such as filters or duplexers, namely for US-based PCS system. Key-advantages of this technology are reduced size and cost at good performance. This workshop will discuss recent advances in the technology and at the device level, such as zero temperature drift, multiple frequency bands on the same wafer, improved power durability, and increased quality factors. Combined with advanced packaging technologies, modules with high functionality can be realized. Beyond replacing other filtering technologies, BAW technology can have a significant impact on system architectures, and will allow novel approaches namely for low power radios. BAW resonators also have a strong potential as high-precision frequency references where they could advantageously replace quartz resonators for this purpose. All these points, as well as design tools and methodology, will be described by the speakers in this workshop.