Shaobo Chen

Design and implementation of an LTCC filter with high stopband rejection

A miniaturized and high stopband rejection bandpass filter(BPF) with three finite transmission zeros is presented in this paper. The BPF with a central frequency of 3.4 GHz and 200 MHz bandwidth is implemented in a novel distributed stripline configuration using LTCC (low-temperature-cofired ceramic) technology. A distinct feature of this filter is excellent out-of-band attenuation performance. The lower skirt of the passband is very steep. There is 36.5dB attenuation at 3.2 GHz, the input/output VSWR is less than 1.4. We employ Z-shape layer to produce the lower 2 transmission zeros. By properly controlling the cross-coupling between the second and the fourth resonator, transmission zero in higher skirt of the passband will be generated. Measurement results of mass production are shown to match well with the electromagnetic simulation, which validate the proposed structure. The overall size of the filter is 4.8mm×4.2mm×1.5 mm.

An ultra broadband 2–18GHz 6-bit PHEMT MMIC digital attenuator with low insertion phase shift

An ultra-wideband (2–18GHz) 6-bit MMIC digital attenuator has been designed. The attenuator has been fabricated with 0.5µm GaAs PHEMT process. Low insertion phase shift has been achieved over the main attenuation states. On-wafer measurement results of the developed MMIC chips in the 2–18GHz band show that the 6-bit MMIC digital attenuator has 31.5dB dynamic range stepped by 0.5dB; attenuation accuracy: +2.31dB/−0.51dB; insertion phase shift: +6.28°/−1.53° referenced insertion loss: <−5.71dB; input/output VSWR: <2.32; chip size: 2.89mm×1.22mm×0.1mm.

A miniaturized LTCC bandpass filter with low insertion loss and high image rejection within 6.5 to 7.1GHz frequency range

A low-temperature-cofired ceramic (LTCC) bandpass filter with low insertion loss and high image rejection is presented for super heterodyne microwave receiver within 6.5–7.1GHz band. By improving the filter cell structure, two transmission zeros can be generated to achieve wide-band image suppression from cascading filter cells. The presented method provides the design flexibility of locating these transmission zeros distributed in the lower and upper stopbands. To reduce insertion loss and size of the filter, a miniaturized LTCC three-stage bandpass filter with two transmission zeros in lower stopband has been implemented for experimental demonstration. The measured insertion loss is less than 1.0 dB at 6.8GHz, the measured image rejection from 5 to 5.6GHz is more than 42dB, the input/output VSWR is less than 1.5. The size of the miniaturized filter is only 2.5mm×2mm×1.2mm. The process yield of the LTCC filter is more than 90%.

Design on antenna switch module for dual band phone (GSM/UMTS) using LTCC technology

This paper presents the results of an antenna switch module integrating a switch (SP9T) and two low-pass filters for harmonic rejection on a low temperature co-fired ceramic (LTCC) substrate. This contributes not only to reduce the size and weight, but also to shorten the development term of RF circuit and simplify the assembly process. It will be used for GSM/UMTS dual mode cellular phones. The 50-ohm in/out FEM utilized a GaAs PHEMT switch is attached to the LTCC substrate. S-parameter characterization of FEM demonstrated excellent insertion, return loss and isolation characteristics of ASM. The final three-dimension model occupied a volume of 4.5mm×3.2mm×1.4mm.

Design and implementation of an miniaturized LTCC filter with high stopband rejection

A miniaturized and high stopband rejection bandpass filter(BPF) with three finite transmission zeros is presented in this paper. The BPF with a central frequency of 3.2 GHz and 200 MHz bandwidth is implemented in a novel distributed stripline configuration using LTCC (low-temperature-cofired ceramic) technology. A distinct feature of this filter is excellent out-of-band attenuation performance. The lower skirt of the passband is very steep. There is 34.6dB attenuation at 3.0 GHz, the input/output VSWR is less than 1.4. We employ Z-shape layer to produce the lower 2 transmission zeros. By properly controlling the cross-coupling between the second and the fourth resonator, transmission zero in higher skirt of the passband will be generated. Measurement results of mass production are shown to match well with the electromagnetic simulation, which validate the proposed structure. The overall size of the filter is 4.8mm×4.2mm×1.5 mm.

Miniaturized LTCC wideband bandpass filter using lumped-element shunt LC resonators

In this letter, shunt LC resonators realized by multilayer spiral inductors and Metal-Insulator-Metal (MIM) capacitors in parallel connection are proposed to design the wideband bandpass filter (BPF) using Low Temperature Co-fired Ceramic (LTCC) technology. A distinct feature of this filter is the ingenious use of mutual coupling and broadside coupling which are introduced by the close packed elements, so as to achieve the coupling between adjacent resonators. With the assistance of the cross coupling which is implemented by a Z-shaped metal layer, a pair of transmission zeros are produced both above and below the passband.

Research on a novel 2∼18 GHz PHEMT MMIC digital attenuator with low insertion phase shift

A novel ultra broadband (2 ~ 18 GHz) 6-bit monolithic microwave integrated circuit(MMIC) digital attenuator with low insertion phase shift is presented. Phase compensation techniques were used in the MMIC design to reduce the insertion phase shift when the attenuation state varies. Performance redundancy optimization strategy was used to get the best performance. This attenuator is fabricated with 0.5μm GaAs PHEMT process. On-wafer measurement results of the developed MMIC chips in the 2-18-GHz band show that the 6-bit MMIC digital attenuator has 0.5 dB resolution and 31.5 dB dynamic attenuation range, input and output VSWR<; 1.8 for all attenuation states, and attenuation accuracy: +2.31dB/-0.51dB; insertion phase shift: +6.28°/-1.53° referenced insertion loss: <;-5.71dB; the chip size is 2.89mm×1.22mm×0.1mm. To ensure high yield, Performance redundancy optimization strategy is used in design, and PCM (Process Control Map) and SPC(Statistics Process Control) technology are used in fabrication. The yield is more than 85%.

Miniaturized lumped element complementary RF LTCC diplexer

The proposed diplexer is composed of complementary bandpass filter and bandstop filter in parallel connection. In the presented 3D physical structure, lumped multilayer inductor and Metal-Insulator-Metal (MIM) capacitor are used to realize the circuit elements. The final structure is verified by 3D Electromagnetic (EM) simulator and good agreement is found between simulation and measurement. The size of the fabricated diplexer is 4.3mm×3.2mm×2.6mm.

A UHF-band miniaturized LTCC band-pass filter with high performance

This letter outlines the design and manufacture of a UHF-band miniaturized band-pass filter realized by low-temperature cofired ceramic (LTCC) technology for super heterodyne microwave receiver applications. A distinct feature of this filter is the smaller size than conventional filter at such a low frequency and steady pass-band temperature electrical performance compared with surface acoustic wave filter. The band-pass filter with a central frequency of 750 MHz and a 40MHz pass-band is designed as a three-dimensional (3-D) structure based on distributed components. This filter has excellent out-of-band attenuation performance and it has 50.1 dB and 56.8 dB of attenuation at 550MHz and 950MHz respectively. The measured insertion loss is less than 2.7 dB at 750MHz, and the input/output VSWR is less than 2.0. The overall size of the miniaturized filter is only 4.5mm×3.2mm×1.5mm.