CMOS broad-band compact high-linearity binary phase-shift keying (BPSK) and IQ modulators are proposed and analyzed in this paper. The modulators are constructed utilizing a modified reflection-type topology with the transmission lines implemented on the thick SiO/sub 2/ layer to avoid the lossy silicon substrate. The monolithic microwave integrated circuit (MMIC) chips were fabricated using standard bulk 0.13-/spl mu/m MS/RF CMOS process and demonstrated an ultracompact layout with more than 80% chip size reduction. The broadside couplers and 180/spl deg/ hybrid for the modulators in the CMOS process are broad-band designs with low phase/amplitude errors. The dc offset and imbalance for the proposed topology are investigated and compared with the conventional reflection-type modulators. The measured dc offset was improved by more than 10 dB. Both BPSK and IQ modulators feature a conversion loss of 13 dB, a modulation bandwidth of wider than 1 GHz, and second- and third-order spur suppressions of better than -30 dBc. The IQ modulator shows good sideband suppression with high local-oscillator suppression from 20 to 40 GHz. The modulators are also evaluated with a digital modulation signal and demonstrate excellent modulator quality and adjacent channel power ratio.

Design and analysis of CMOS broad-band compact high-linearity modulators for gigabit microwave/millimeter-wave applications

The latest wireless products demand ever-greater functionality, higher performance, and lower cost in smaller and lighter formats. This demand has been satisfied to date by major advances in integrated circuits and high-density packaging technologies, even though the RF sections have been continuing to demand high-performance and miniaturized passive components such as matching and filtering circuitries. Continuing reductions in the size of discrete surface-mounted components are having diminishing returns because of the incompatibility of printed circuit board (PCB) technology as well as the high cost of assembly for those tiny discrete components. Therefore, new technological approaches are required to address the integration of passives. One of the important means today for integrating passives, particularly for RF functions, is low temperature cofired ceramics (LTCCs). Besides the use of this technology for highly integrated RF front-end modules [1]‐[4], there has also been a great deal of interest in realizing compact LTCC-embedded or isolated components, ranging from traditional baluns [5], couplers [6], and filters [7]‐[10] to more sophisticated diplexers [11] and balanced filters [12]‐[13], for different wireless communication technologies such as mobile phones, Bluetooth, and/or wireless LAN (WLAN) equipped terminals. This article specifically focuses on the design and implementation details for lumped or semi-lumped LTCC bandpass filters. A variety of LTCC chip-type filters with different characteristics are widely available commercially. They are often specified by the center frequency, fractional bandwidth, insertion loss, and stopband attenuation. Some examples are given in Table 1. These filters are usually second-order or third-order and have their responses optimized for specific applications by taking advantage of flexible filtering characteristics of LTCC LC filters. In general, their design process starts with a schematic circuit usually obtained by computer-aided design techniques from which a physical layout realization is generated through electromagnetic (EM) simulation tools. Nevertheless, the conventional analytical design methods can always be used as a starting point in the design process. The general design procedure for an LTCC filter can be summarized as • derive a schematic circuit including parasitic elements • optimize the circuit to meet required specifications • generate a physical layout based on the circuit • tune the layout to meet required specifications • fabricate prototypes to verify the performance. Each of these steps has its own design aspects and should be addressed carefully. Generally, layout tuning is the most time-consuming step as it involves full-wave EM simulations. Therefore, having a good layout design to minimize the number of simulations is of primary concern. As miniaturized LTCC filters are usually second-order or third-order, their layouts should not be too complicated. Indeed, there are some well-known standard layout strategies that are commonly used in practice. In the following section, we will discuss some important issues for the whole design process.

https://www.ee.cuhk.edu.hk/~klwu/pdf/microwave_magazine_oct_08.pdf

Low-Temperature Cofired Ceramic LC Filters for RF Applications

Over the past few years, a great amount of effort has been spent on LTCC filters or related research [21]?[28]. Some of these components have more advanced functionalities, such as a combination of filter and balun, or a complete front-end module with balun, filter, and matching network. At the same time, advanced methodologies have also been developed to design these components [29]. All the enjoyment of miniaturized RF components or modules is due to the promising three-dimensional design flexibility of LTCC technology. It is expected that a variety of functionally complex components will be continuously available on the market such that the cost and size of the overall wireless terminal can be further reduced. Various aspects of designing miniaturized LTCC LC filters have been briefly discussed here. Conventional coupled LC resonators are commonly used in LTCC filters for RF applications because of their compact size advantage. The shunted parallel resonator in this type of filter can be realized directly as a lumped-element or distributed quarter- wavelength stripline with or without loaded capacitors. Filters with distributed resonators in general have better passband insertion loss performance. Moreover, there are many ways to improve the rejection performance in an LTCC filter design; for example, by modifying the resonators or admittance inverters so as to introduce transmission zeros at the stopband. It was demonstrated, through a design example, that by making use of the flexibility of LTCC technology, a compact LC bandpass filter can be realized for various RF applications.

Low-temperature cofired ceramic LC filters for RF applications [Applications Notes]

A highly integrated transceiver module for 5.8 GHz OFDM communication system is presented. The antenna and filter are directly fabricated on the module using multi-layer packaging technology in order to reduce size and interconnection losses. A cavity backed patch antenna with a vertical feed and an embedded 3D filter have been designed and integrated on the package using a low-temperature cofired ceramic (LTCC) process. RF functional blocks including PA, LNA, mixers and VCO are developed using GaAs-based MMICs and are attached on the surface of the LTCC board. RF blocks are vertically stacked and connected through via structures. The specifications of the functional blocks have been determined and verified through system simulations based on the IEEE 802.11a standard. The total size of the module is 14/spl times/19/spl times/2 mm/sup 3/. Measurement and simulation results of the components and the module are also presented.

A highly integrated transceiver module for 5.8 GHz OFDM communication system using multi-layer packaging technology

A new chip-type multi-layer ceramic balun is presented in this paper. This balun is designed in the ISM band and fabricated using low temperature co-fired ceramic (LTCC) technology. It involves the semi-lumped concept and the multi-layer structure to realize the LTCC-MLC balun. The symmetric structure provides the excellent characteristics of phase balance and amplitude balancing. Measured results of the LTCC-MLC balun match well with the computer simulation.

A semi-lumped balun fabricated by low temperature co-fired ceramic

Chip monolithic directional couplers and baluns have been gaining popularity due to the increasing demand of wireless telecommunication equipment. These multilayer components are meeting demands by allowing for smaller board space requirement, ease of surface mount assembly and their relative low cost. Spiral Broadside Coupled Striplines (SBCS) using Low Temperature Co-fired Ceramic (LTCC) are presented as a novel technique of fabricating the ultra-miniature chip directional couplers and the baluns. SBCS structure contributes dramatically to the reduction of the board space and the height compared with conventional Broadside Coupled Striplines (BCS). Electromagnetic principals, structures, electrical properties including scattering parameters (S-parameters) and power handling capabilities of the ultra-miniature chip directional couplers and the baluns utilizing SBCS structure are introduced. In addition, the rapid development and quality advantages of LTCC SBCS structures are discussed.

T. Morikawa

Papers

Chip type spiral broadside coupled directional couplers and baluns using low temperature co-fired ceramic