In order to realize millimeter-wave (MMW) 3-D system-in-package (SiP) front-end modules, we propose a 60-GHz band copper ball vertical interconnection structure, which interconnects between vertically stacked substrates. The structure enables ICs to be placed between the vertically stacked substrates. Since the diameter of the copper balls must exceed the thickness of the ICs, the distance between the substrates in the modules is larger than that of the flip-chip interconnection widely used in the MMW-band. Therefore, the conventional flip-chip interconnection does not scale for the interconnection between the substrates in MMW 3-D SiP front-end modules. The layout of grounded copper balls and the patterns of inner ground layers in the upper/lower substrates are designed using 3-D electromagnetic field simulation. The designed structure allows less than 1 dB transmission loss up to 71.1 GHz, compared with a through transmission line. The result is verified with fabrication and measurement and confirms the feasibility of MMW 3-D SiP front-end modules.

This paper proposes 1-bit feedforward distortion compensation for digital radio frequency conversion (DRFC) with 1-bit bandpass delta-sigma modulation (BP-DSM). The 1-bit BP-DSM allows direct RF signal transmission from a digitally modulated signal. However, it has been previously reported that 1-bit digital pulse trains with non-ideal rectangle waveform cause spectrum regrowth. The proposed architecture adds a feedforward path with another 1-bit BP-DSM and so can cancel out the distortion components at any target carrier frequency. Both the main signal and the distortion compensation signal are 1-bit digital pulse trains and so no additional analog RF circuit is required for distortion compensation. Simulation results show that the proposed method holds the adjacent channel leakage ratio to 60dB for LTE signal transmission. A prototype of the proposed 1-bit DRFC with an additional 1-bit BP-DSM in the feedforward path shows an ACLR of 50dB, 4dB higher than that of the conventional 1-bit DRFC.

A low cost, ultra small Radio Frequency (RF) transceiver module with integrated antenna is one of the key technologies for short range millimeter-wave wireless communication. This paper describes a 60 GHz-band transmitter module with integrated dipole antenna. The module consists of three pieces of low-cost organic resin substrate. These substrates are vertically stacked by employing Cu ball bonding 3-dimensional (3-D) system-in-package (SiP) technology and the MMIC's are mounted on each organic substrates by using Au-stud bump bonding (SBB) technique. The planer dipole antenna is fabricated on the top of the stacked organic substrate to avoid the influence of the grounding metal on the base substrate. At 63 GHz, maximum actual gain of 6.0 dBi is obtained for fabricated planar dipole antenna. The measured radiation patterns are agreed with the electro-magnetic (EM) simulated result, therefore the other RF portion of the 3-D front-end module, such as flip chip mounted IC's on the top surface of the module, does not affect the antenna characteristics. The results show the feasibility of millimeter-wave low cost, ultra small antenna integrated module using stacked organic substrates.

The 1-bit band-pass delta-sigma modulator (BP-DSM) achieves high resolution if it uses an oversampling technique. This method can generate concurrent dual-band RF signals from a digitally modulated signal using a 1-bit digital pulse train. It was previously reported that the adjacent channel leakage ratio (ACLR) deteriorates owing to the asymmetrical waveform created by the pulse transition mismatch error of the rising and falling waveforms in the time domain and that the ACLR can be improved by distortion compensation. However, the reported distortion compensation method can only be performed for single-band transmission, and it fails to support multi-band transmission because the asymmetrical waveform compensated signal extends over a wide frequency range and is itself a harmful distortion outside the target band. Unfortunately, the increase of out-of-band power causes the BP-DSM unstable. We therefore propose a distortion compensator for a concurrent dual-band 1-bit BP-DSM that consists of a noise transfer function with a quasi-elliptic filter that can control the out-of-band gain frequency response against out-of-band oscillation. We demonstrate that dual-band LTE signals, each with 40MHz (2×20MHz) bandwidth, at 1.5 and 3.0GHz, can be compensated concurrently for spurious distortion under various combinations of rising and falling times and ACLR of up to 48dB, each with 120MHz bandwidth, including the double sided adjacent channels and next adjacent channels, is achieved.

We have already proposed synchronized spread spectrum code division multiple access (SS-CDMA) for the Quasi-Zenith Satellite System (QZSS) safety confirmation system to be used in times of great disaster. In this system, the satellite reception timings of all uplink signals are synchronized using a transmission timing control method in order to realize high-density user multiple access. An issue that should be addressed in order for this system to be viable is the error that can occur in the satellite reception timing. This error occurs due to the terminal time deviation and the error in calculating the propagation delay to the satellite. In this paper, we measure the terminal time deviation and the propagation delay calculation error at the same time by using the same receivers and evaluate the satellite reception timing error of the uplink signal. By this measurement, it is shown that satellite reception timing error within 50ns can be realized in 99.98% of mobile terminals. This shows that the synchronized SS-CDMA with the transmission timing control method has a potential to realize the QZSS short message system with high-density user multiple access.

This paper presents a theoretical analysis of a tunable resonator using a coupled line and switches for the first time. The tunable resonator has the capability to tune its resonant frequency and bandwidth. The resonator has two suitable features on its tunable capability. The first feature is that the resonator retains its resonant frequency during bandwidth tuning. The second feature is that the on-state switch for tuning the bandwidth does not affect the insertion loss at the resonant frequency. These features are theoretically confirmed by its mathematically derived input impedance. The results from electromagnetic simulation and measurement of the fabricated tunable resonator also confirm these features. The fabricated tunable resonator changes the resonant frequency from 2.6 GHz to 6.4 GHz and bandwidth between 9% and 55%.

A 2-D beam scanning array antenna fed by a compact 16-way 2-D beamforming network (BFN) designed in Broadside Coupled Stripline (BCS) is addressed. The proposed 16-way 2-D BFN is formed by interconnecting two groups of 4x4 Butler Matrix (BM). Each group is composed of four compact 4x4 BMs. The critical point of the design is to propose a simple and compact 4x4 BM without crossover in BCS to achieve a better transmission coefficient of the 16-way 2-D BFN with reduced size of merely 0.8λ0×0.8λ0×0.04λ0. Moreover, the complexity of the interface connection between the 2-D BFN and the 4x4 patch array antenna is reduced by using probe feeding. The 16-way 2-D BFN is able to produce the phase shift of ±45°, and ±135° in x- and y- directions. The 2-D BFN is easily integrated under the 4x4 patch array to form a 2-D phased array capable of switching 16 beams in both elevation and azimuth directions. The area of the proposed 2-D beam scanning array antenna module has been significantly reduced to 2λ0×2λ0×0.04λ0. A prototype operating in the frequency range of 4-6GHz is fabricated and measured to validate the concept. The measurement results agree well with the simulations.

In this article, a new Beamforming Network (BFN) realized in Broadside Coupled Stripline (BCS) is proposed to feed 1×4 and 2×2 arrays antenna at 28 GHZ-Band. The new BFN is composed only of couplers and phase shifters. It doesn't require any crossover compared to the conventional Butler Matrix (BM) which requires two crossovers. The tight coupling and low loss characteristics of the BCS allow a design of a compact and wideband BFN. The new BFN produces the phase differences of (±90°) and (±45°, ±135°) respectively in x- and y-directions. Its integration with a 1×4 linear array antenna reduces the array area by 70% with an improvement of the gain performance compared with the conventional array. The integration with a 2×2 array allows the realization of a full 2-D beam scanning. The proposed concept has been verified experimentally by measuring the fabricated prototypes of the BFN, the 1-D and 2-D patch arrays antennas. The measured 11.5 dBi and 11.3 dBi maximum gains are realized in θ0 = 14° and (θ0, φ0) = (45°,345°) directions respectively for the 1-D and 2-D patch arrays. The physical area of the fabricated BFN is only (0.37λ0×0.3λ0×0.08λ0), while the 1-D array and 2-D array antennas areas without feeding transmission lines are respectively (0.5λ0×2.15λ0×0.08λ0) and (0.9λ0×0.8λ0×0.08λ0).

A 2 to 5 GHz-band self frequency dividing quadrature mixer utilizing current re-use configuration with small size and broad band operation is proposed for a direct conversion receiver and a low-IF receiver of cognitive radio. The proposed mixer operates at twice the LO frequency by directly using a static type flip-flop frequency divider as the LO switching circuit for quadrature signal generation. The current re-use configuration is realized because the dc current of the frequency divider and the RF common-emitter amplifier share the same current flow path. Simulations and experiments verify that the proposed mixer offers broad band operation, miniaturization, and low power consumption. The mixer IC fabricated by 0.35 µm SiGe-BiCMOS technology achieved the conversion gain of 20.6 dB, noise figure of 11.9 dB and EVM for π/4-shift QPSK signal of 4.4% at 2.1 GHz with power consumption of 15 mW and size of 0.22 0.31 mm2. For the confirmation of broad band operation, the characteristics of conversion gain and noise figure were measured at 5.2 GHz. The proposed mixer could operate at 5.2 GHz with enough conversion gain, but the noise figure was inferior to that of 2.1 GHz. Therefore the further investigation and improvement about the noise figure will be needed for higher frequency.

A novel analysis method of the intermodulation (IM) and the noise power ratio (NPR) of multiple-carrier amplifiers is descrided. This method, based on Discrete Fourier Transform, allows an accurate calculation of IM and NPR of the amplifier having multiple carriers by directly using measured single-carrier amplitude and phase characteristics. This method has an outstanding feature in that it can be applied to the general case of n carriers having an arbitrary power level as long as frequency-dependence of amplitude and phase characteristics is negligibly small. Applying this method to the linearized amplifier, a good agreement between measured and calculated results for IM3, IM5, and NPR has been obtained for operation from linear up to saturation, which shows this method would be a good candidate for calculating IM and NPR of multiple-carrier amplifiers.

Even though BiCMOS process has an ability to make both BJT and MOSFET on single-chip, only BJT has been used for BiCMOS Si-MMIC LNA because of its low noise and high gain performance under low d. c. supply power. But the distortion performance of BJT should be improved for the receiver applications in some wireless systems. In this paper, intermodulation distortion characteristics comparison is carried out between BJT and MOSFET fabricated in the same BiCMOS process by the analysis based on the simplified transistor models with extracted device parameters. The analytical result shows that MOSFET has lower intermodulation distortion characteristics compared with BJT, and the result is evaluated by the measurements. In order to obtain both low distortion and low noise characteristics, a two-stage Si-MMIC LNA is developed by using BJT as the 1st stage and MOSFET as the 2nd stage of LNA. The fabricated LNA performs NF of 2.45 dB, gain of 19.3 dB, IIP3 of14.6 dBm and OIP3 of 4.7 dBm under 3 V/7.2 mA d. c. supply power.

For capacity expansion of the Quasi-Zenith Satellite System (QZSS) safety confirmation system, frame slotted ALOHA with flag method has previously been proposed as an access control scheme. While it is always able to communicate in an optimum state, its maximum channel efficiency is only 36.8%. In this paper, we propose adding a reservation channel (R-Ch) to the frame slotted ALOHA with flag method to increase the upper limit of the channel efficiency. With an R-Ch, collision due to random channel selection is decreased by selecting channels in multiple steps, and the channel efficiency is improved up to 84.0%. The time required for accommodating 3 million mobile terminals, each sending one message, when using the flag method only and the flag method with an R-Ch are compared. It is shown that the accommodating time can be reduced to less than half by adding an R-Ch to the flag method.

For on-chip matching Si-MMIC fabricated on a conventional low resistivity Si substrate, the loss of on-chip inductors is quite high due to the dielectric loss of the substrate. In order to reduce the loss of on-chip matching circuit, the use of high resistivity Si substrate is quite effective. By using electro-magnetic simulation, the relationship between coplanar waveguide (CPW) transmission line characteristics and the resistivity of Si substrate is discussed. Based on the simulated results, the resistivity of Si substrate is designed to achieve lower dielectric loss than conductor loss. The effectiveness of high resistivity Si substrate is evaluated by the extraction of equivalent circuit model parameters of the fabricated on-chip spiral inductors and the measurement of the fabricated on-chip matching Si-MMIC LNA's.

The 1-bit digital radio frequency (DRF) transmitter using a band-pass delta-sigma modulator (BP-DSM) can output a radio frequency (RF) signal carrying a binary data stream with a constant data rate regardless of the carrier frequency, which makes it possible to transmit RF signals over digital optical links with a constant bit rate. However, the optical link requires a line coding, such as 8B10B or 64B66B, to constrain runlength and disparity, and the line coding corrupts the DRF power spectrum owing to additional or encoded data. This paper proposes a new line coding for BP-DSM, which is able to control the runlength and the disparity of the 1-bit data stream by adding a notch filter to the BP-DSM that suppresses the low frequency components. The notch filter stimulates the data change and balances the direct current (DC) components. It is demonstrated that the proposed line coding shortens the runlength from 50 bits to less than 8 bits and reduces the disparity from several thousand bits to 5 bits when the 1-bit DRF transmitter outputs an LTE signal with 5 MHz bandwidth, when using carrier frequencies from 0.5GHz to 2GHz and an output power variation of 60dB.

The 1-bit band-pass delta-sigma modulator (BP-DSM) achieves high resolution by using the oversampling technique. This method allows direct RF signal transmission from a digitally modulated signal, using a 1-bit digital pulse train. However, it has been previously reported that the adjacent channel leakage ratio (ACLR) in a target frequency band degrades due to the pulse transition mismatch between rising and falling waveforms in the time domain. This paper clarifies that the spurious distortion in BP-DSM is caused by the asymmetricity of the waveform about the center of an eye pattern in the time axis, and proposes a 1-bit BP-DSM with the compensator consisting of a fractional delay filter and a binary data differentiator to cancel out the asymmetry in the target frequency band. This can accurately provide a wideband cancellation signal with more than 100MHz bandwidth, including the adjacent channel, within 50dB power dynamic range. Using long term evolution (LTE) signals with 5MHz bandwidth at 0.8GHz, we simulated the spurious distortion, performing various combinations of rising and falling times in the eye pattern, and the proposed 1-bit BP-DSM always achieved high ACLR, up to 60dB, in 140MHz bandwidth, under all conditions.

In this paper, we propose a radio frequency (RF) anti-aliasing filter design method considering the effect of a roll-off characteristic on a noise figure (NF) in the direct RF undersampling receiver. The proposed method is useful for broadband reception that a system bandwidth (BW) has nearly half of the sampling frequency (1/2 fs). When the system BW is extended nearly 1/2 fs, the roll-off band is out of the desired Nyquist zone and it affects NF additionally. The proposed method offers a design target regarding the roll-off characteristic not only the rejection ratio. The target is helpful as a design guide to meet the allowed NF. We design the filter based on the proposed method and it is applied to the direct RF undersampling on-board receiver for Ka-band high throughput satellite (HTS). The measured NF value of the implemented receiver almost matched the designed value. Moreover, the receiver achieved the reception bandwidth which is 90% of 1/2 fs.

This paper presents an even harmonic quadrature mixer (EH-QMIX) with a simple filter configuration and an integrated LTCC module including LNAs, band rejection filters (BRFs), and the proposed EH-QMIX for W-CDMA direct conversion receiver (DCR). Since the DCR has no spurious responses, a BRF instead of a high-Q band pass filter can be applicable for eliminating undesired signals and it can be built in the LTCC substrates easily. As LO frequency is half of RF frequency in the EH-QMIX, diplexer can be composed of simple filters and it can be also integrated in the substrates. As a result, the whole RF circuits of the EH-DCR using a proposed EH-QMIX are integrated in the LTCC module and miniaturization of the receiver is achieved. Moreover, in order to suppress the degradation of the amplitude and the phase imbalances in the quadrature mixer caused by interferences of signals, RF characteristics of the circuits in the mixer such as reflection coefficients, isolations are discussed. A developed LTCC module shows good performances for W-CDMA direct conversion receiver.

This paper proposes a heterogeneous wireless network with handover in the application layer. The proposed network requires no upgrade of wireless infrastructure and mobile terminals to convert the present homogeneous networks to the proposed heterogeneous network. Only installing application programs on the content server side and the mobile terminal side is required. The performance of the proposed network has been evaluated in a field trial using a mobile broadband wireless access (MBWA) air interface with wide coverage and a wireless local area network (WLAN) air interface with high throughput. The field trial results show that the maximum value of the handover outage time is only 170 ms. The proposed heterogeneous wireless network is promising since both high throughput and wide coverage area are attained by a combination of the proposed handover scheme with the present homogeneous wireless networks.

A novel common emitter common collector transistor pair (CECCTP) mixer is presented. A LO pumped CECCTP enables even harmonic mixing operation, and a balanced CECCTP mixer configuration enables the suppression of both 2fLO and fIM2 which are undesirable component for direct conversion mixer. A 2 GHz-band balanced CECCTP mixer is fabricated in SiGe HBT process, and the direct conversion characteristics are measured. It performs conversion gain of 8.8 dB, NF of 14.9 dB and IIP2 of 42.3 dBm when LO power is -6 dBm, supplied voltage is 3 V and current is 5 mA.