60 GHz LTCC 3D cavity bandpass filter with two finite transmission zeros

Abstract

A novel 60 GHz three-dimensional (3D) cavity bandpass filter using low-temperature co-fired ceramic technology is presented. The proposed filter shows two finite transmission zeros with each at either side of the passband using the extracted-pole and cross-coupling techniques. Both simulated and experimental results of the filter are described.Introduction: In most countries, several gigahertz of bandwidth is now available in the 60 GHz band. The three-dimensional (3D) integration approach using multilayer low-temperature co-fired ceramic (LTCC) technologies has emerged as an attractive solution for these 60 GHz systems owing to its high level of compactness and mature multilayer fabrication capability. Various bandpass filters [1-4] based on LTCC and the substrate integrated waveguide (SIW) have been introduced for V-band applications. To develop a high-isolation diplexer for the 60 GHz applications, two narrowband bandpass filters operating at two adjacent frequencies could be employed as in [2]. It is noted that the bandpass filter has no finite transmission zeros so that the isolation between two channels of the diplexer may not be optimised. An LTCC V-band dual-mode filter with two transmission zeros was presented in [4] by using cross-coupling. However, it has a poor in-band performance and its transmission zeros cannot be controlled independently.In this Letter, we present a 60 GHz narrowband cavity bandpass filter having two finite transmission zeros to meet the need of sharp cutoff skirts. The transmission zero below the passband is achieved by using the extracted-pole technique [5 -7] while the transmission zero above the passband is achieved by using the cross-coupling technique [8,9]. These two transmission zeros can be controlled individually to the desired frequencies. The designed high-selectivity narrowband bandpass filter can be further employed to develop a high-isolation V-band diplexer.

Compact 60 GHz low‐temperature cofired ceramic filter with quasi‐elliptic bandpass response

“…Similar to the 60 GHz (V-band) LTCC filters reported in [5][6][7][8][9], the insertion loss of the proposed filter highly depends on the dielectric loss of LTCC substrates. This is because the incident wave must penetrate the LTCC substrate to excite the stacked SIW cavities.…”

Substrate integrated waveguide filter with mixed coupled modified trisections

“…In [6], an LTCC narrowband SIW filter with two TZs for V-band application is presented. Although the structures in [4][5][6] are comparatively compact, their selectivity and upper stopband need to be improved.In this Letter, a miniaturised SIW filter with an improved stopband using cascade MCMTs is presented. By implementing mixed coupling into two cascade modified trisections (MT), the proposed three-order SIW filter not only has four TZs to improve frequency selectivity and upper stopband, but also has a small size by profiting from its LTCC multilayer structure.…”

“…In [4,5], X-band LTCC trisection SIW filters with one TZ are introduced. In [6], an LTCC narrowband SIW filter with two TZs for V-band application is presented. Although the structures in [4][5][6] are comparatively compact, their selectivity and upper stopband need to be improved.…”

Analysis and design of efficient passive components for the millimeter-wave and THz bands

“…A photograph of the manufactured prototype is shown in each graph inside the blue-marked inset. a) Microstrip CMOS filter of [968]; b) Microstrip BiCMOS filter of [969]; c) LTCC Stripline filter of [970]; d) LTCC cavity filter of [973]; e) LTCC cavity filter of [974]; f) LTCC cavity filter of [975].…”

“…Despite of the observed frequency shift, a common degradation in V-band prototypes [973]- [975], the presented prototype results competitive for the V-band due to its outstanding low insertion losses. In addition, good selectivity and a flat response are obtained.…”