Andreas Przadka

Ceramics: the platform for duplexers and frontend-modules

In the last few years a significant trend from singleband to multiband applications has been observed, especially evident on GSM based phones. Four years ago singleband phones were standard. Today they have been fully substituted by dualband phones even for low end applications, and tripleband handsets for the high end market. In the near future quadband including GSM 850 will be established on the market. Adding third generation services to the existing second generation phones will lead to even more,complex systems. This continuing move towards higher functionality and increased complexity of the antenna interface is in contradiction to the requirements for smaller size, shorter development, cycles as well as cost and component count reduction. These objectives can only be met by a new level of integration of discrete passive and active components. Whereas the digital part is already highly integrated and of small size, the RF front-end section consists of a large number of components assembled on a printed circuit board. In the first step of integration the switching between different bands and modes was comprised in an antenna switch module (ASM). In the next step a front-end module (FEM) includes the surface acoustic wave filters (SAW filters) and dozens of matching elements. This development has been made possible by the utilization of LTCC technology (low temperature co-fired ceramics). Compared to FR4, LTCC is a low loss, high precision substrate allowing to integrate a large number of passive devices in a small volume. For example duplexers consisting of Tx and Rx bandpass filters for instance used in CW radio systems, or the UMTS/FDD mode, or diplexers for the 800 and 1900 MHz band allow with LTCC the smallest possible size. This paper covers the main issues of the design of LTCC based FEMs and duplexers. It focuses especially on the increase in overall system performance due to the reduction of external interfaces as well as optimization of internal interfaces in the RF chain.

Concepts for RF Front-Ends for Multi-Mode, Multi-Band Cellular Phones

This paper describes front-end architectures of modern multi-mode, multi-band cellular phones and will discuss the requirements on RF filtering in such applications. Special focus will be on dual mode (GSM and WCDMA) cellular phones with four GSM and three WCDMA bands. On the one hand driven by forward integration - e.g., from PA function via transmit front-end to a fully integrated radio - on the other hand influenced by new requirements of 3G systems and the integration of complementary access, filtering components such as SAW and BAW filters have to solve several increased requirements simultaneously. New technologies are required to follow the demand of increased RF performance, reduced PCB area consumption and continuously decreasing component costs.

Integration of WCDMA Band VIII Duplexer on an LTCC Platform

In the third generation wireless technology, mobile phones are expected to deliver faster data rates to incorporate higher functionality. Currently the WCDMA (Wideband Code Division Multiple Access) technology is capable of meeting the demands of the rapidly growing market requirements. The Band VIII is now being introduced in Europe to augment Band I. In this paper we discuss the integration of Band VIII duplexer on an LTCC (Low Temperature Co-fired Ceramic) substrate which can act as a part of a module for the upcoming 3G multi-band mobile phones.

Multilayer LTCC bandpass filter design

This paper describes the design and performance of a band-pass filter for wireless communication systems implemented in a low temperature co-fired ceramic (LTCC) substrate. The designed filter provides enhanced stopband characteristics and occupies a small volume in the substrate. The proposed filter shows low insertion loss in the 1710-1910 MHz band and offers high rejection at 824-915 MHz, at the harmonic frequencies and for the Bluetooth/WLAN (IEEE 802.11 b/g) band (2400... 2500 MHz). For the passband the measured insertion loss was better than -1 dB. The rejection for 824...915 MHz was more than 15 dB and for the harmonics more than 30 dB. For the Bluetooth/WLAN band the rejection was more than -20 dB.

High Performance WCDMA1900 Combined LTCC/SAW/BAW Duplexer for Mobile Phones

In this paper are presented a design and a performance of a duplexer for WCDMA systems combined of a low temperature co-fired ceramic (LTCC) substrate, a surface acoustic wave (SAW) filter and a bulk acoustic resonance (BAW) filter. The designed duplexer provides enhanced stopband characteristics and occupies a small volume. The insertion losses are better than -3.8 dB in the 1850-1910 MHz and 1930-1990 MHz bands and the rejection of the out-of-band frequencies till 2.5 GHz is higher than -38 dB.