Shigeru Hiura

Full RF module with embedded filters for 2.4 GHz and 5 GHz dual band WLAN applications

Small size radio frequency (RF) multi chip module for dual band (2.4 GHz and 5 GHz) wireless local area network (WLAN) applications is described. The full functions between base band input/output (I/O) and RF antenna switch are integrated in the RF module. In order to reduce size of the RF module, embedded 5 GHz band pass filter (BPF), build-up multi-layer organic substrate and flip chip technology are used. Size of the RF module is 24 mm/spl times/32 mm/spl times/2.1 mm, including shield cover and connectors. This is the minimum size in modules with same functions for dual band WLAN as far as the authors know. And electrical performances of the RF module are evaluated using WLAN signals. This report presents design and experimental results of small size RF module for dual band WLAN applications.

High-efficiency 400 W power amplifier with dynamic drain voltage control for 6 MHz OFDM signal

In this paper, we present a high-efficiency 400 W power amplifier (PA) for a 6 MHz orthogonal frequency division multiplexing (OFDM) signal with a 10 dB peak-to-average power ratio (PAPR). To improve the efficiency of the PA at a 10 dB backoff from its saturated output power (PSAT), a dynamic drain voltage control is applied, which supplies two different drain voltages depending on the envelope of the OFDM signal. The PA is fabricated using a 400 W push-pull laterally diffused metal oxide semiconductor (LDMOS) field-effect transistor (FET) for an ultrahigh frequency (UHF) band. The drain current of a single LDMOS FET is 9.5 A at PSAT. The drain voltages used in the control are set to 40 V and 20 V. Measurement results indicate a power-added efficiency (PAE) in the case of dynamic drain voltage control of 34%, which is 15% higher than PAE at a drain voltage of 40 V. This is the highest output power of a PA with a dynamic drain voltage control to the best of our knowledge.

RF module using MCM-L and BGA technology for 5 GHz WLAN application

This paper presents the design concept and experimental results about small size radio frequency (RF) module for 5GHz wireless local area network (WLAN). Functions of the RF module include from base band input/output to antenna switch. The size is 20mm × 15mm × 3mm and that is minimum size in modules with same functions as far as the authors get to know. For the purpose of small size and low cost, generally known technologies are used. They are multi chip module on laminated-base dielectric substrate (MCM-L) technology, interconnection of each layer using build-up technology, flip chip technology and ball grid array (BGA) technology. Parts and ICs are on both sides of the RF modules substrate and are vertically connected in the substrate. In order to ensure electrical performance at 5GHz frequency band in the high-density package, transmission line characteristics in the substrate and BGA characteristic are simulated by 3 dimensional (3D) electromagnetic (EM) software. The fabricated RF module is evaluated using the test set up for 5GHz WLAN application and the result is shown.

UWB module with antenna using organic substrates

This paper presents the ultra wideband (UWB) module which contains an antenna, switches and a low noise amplifier (LNA). In order to accomplish small size and low cost, the antenna is designed using organic substrates and other parts are fabricated on the same printed circuit board (PCB) as the antenna. Size of the antenna is 20 mm times 15 mm and size of the UWB module is 20 mm times 35 mm. The antenna is designed by three-dimensional electromagnetic (3D EM) simulator. Input VSWR and radiation patterns of the antenna are measured. Measurement results confirm that the performance of the fabricated antenna is similar to simulation results. Input VSWR is less than 1.6 at the frequency band of 3 GHz to 5 GHz. Data transmission rate of the module is simulated using the measured antenna parameters. Results of system simulation show that the module is useful for UWB applications. This is the first report of a UWB module with an antenna using organic substrates as far as authors get to know

Asymmetrical Doherty amplifier using GaN HEMTs for high-power applications

In this paper, we present an asymmetrical Doherty amplifier (DA) that can enhance the efficiency at a 9.5 dB backoff from its saturated output power (PSAT). The asymmetrical DA consists of a peak amplifier and a carrier amplifier with two and one 210 W gallium nitride (GaN) high-electron-mobility transistors (HEMTs), respectively. A Wilkinson combiner at the output of the peak amplifier enables the stable operation of the GaN HEMTs for high-power applications. The asymmetrical DA is designed and fabricated for the ultrahigh-frequency (UHF) band. Measurement results using a continuous wave (CW) signal indicate a drain efficiency (ηd) of 60% at a PSAT of 57.5 dBm and a ηd of 56% at a 9.5 dB backoff from PSAT. For a 6 MHz orthogonal frequency-division multiplexing (OFDM) signal with a high peak-to-average power ratio (PAPR), the measurement results indicate a ηd of 52% and an adjacent-channel leakage power ratio (ACLR) of -41 dBc at an average output power (PAVE) of 48 dBm using a digital predistorter. To the best of our knowledge, this is the highest ηd and output power for an OFDM signal.

Electro-thermal simulation in the time domain of GaN HEMT for RF switch-mode amplifier

Accurate transient temperature prediction in GaN devices is an increasingly important process in the design of dependable radio frequency systems. In this paper, a methodology for dynamic electro-thermal simulation of GaN microwave and power devices is presented, which bases on the extraction of compact thermal models by three-dimensional finite element simulation. The obtained compact thermal model is coupled to an electric compact model, where the temperature dependence of the lumped elements is described analytically. The proposed methodology is applied to the case of GaN HEMTs used in a voltage mode D-class radio frequency amplifier operated in the frequency range from 300 MHz up to 3 GHz.

Doherty power amplifier with asymmetrical drain voltages for enhanced efficiency at 8 dB backed-off output power

In this paper, we present a high-efficiency 300 W Doherty power amplifier (DPA) that can improve the efficiency at an 8 dB backoff from its saturated output power (PSAT). To enhance the efficiency, asymmetrical drain voltages are supplied to a carrier amplifier and a peak amplifier in the DPA. The drain voltages and radio frequency (RF) circuit parameters of each amplifier are determined by basic load-impedance analysis. The DPA is fabricated using a push-pull laterally diffused metal oxide semiconductor (LDMOS) field-effect transistor (FET) for an ultrahigh frequency (UHF) band. The drain voltages are set to 50 V and 30 V. Measurement results using a continuous wave (CW) signal indicate a drain efficiency (ηd) of 50% at a PSAT of 55 dBm and a ηd of 48% at an 8 dB backoff from PSAT, which means that the proposed DPA can extend the power range in which its highest efficiency is maintained. For a wideband code division multiple access (W-CDMA) signal with a peak-to-average power ratio (PAPR) of 8 dB, the measurement results indicate a ηd of 43% and an adjacent-channel leakage power ratio (ACLR) of −23 dBc at an output power of 47 dBm.

RF Design of On-Chip EMI Filters in CMOS Logic IC

In this paper, we present new design methods that provide the radio frequency (RF) rejection performance of on-chip electromagnetic interference (EMI) filters in a complementary metal-oxide semiconductor (CMOS) logic integrated circuit (IC). In order to simulate on-chip performance, we consider the following concepts. Firstly, simulation models consist of simulation program with integrated circuit emphasis (SPICE) models of logic circuits, an IC chip design, an IC package design and a printed circuit board (PCB) design. Secondly, RF rejection performance is obtained using a frequency domain analysis of output data signals from ICs including and excluding EMI filters. Simulation results show that an on-chip-type EMI filter has better performance in the frequency band for wireless communications than other types of EMI filter. The measurement results show good agreement with the simulation results.

Millimeter-wave MEMS capacitive switch in vacuum-sealed in-line wafer level package

In this paper, we present a millimeter-wave microelectromechanical systems (MEMS) switch with a microsecond switching time. The optimization of the mechanical structure, application of high actuation voltages and encapsulation with a vacuum-sealed package result in a higher speed with which a beam of the MEMS switch is pulled in and pulled out. In order to reduce the packaging cost, we encapsulate the MEMS switch using an in-line wafer level package (WLP) which is built during the same complementary metal-oxide semiconductor (CMOS) process in which the MEMS switch is built. The fabricated MEMS switch is a shunt circuit and capacitive contact type. The dimensions of the in-line WLP are 500 µm wide by 500 µm long. The measurement results show an insertion loss of 0.5 dB and an isolation of 15 dB at a frequency of 50 GHz. The measured switching time is 2.0 µs or less. This is the shortest switching time of a MEMS capacitive switch for millimeter wave applications as far as the authors know.