Kensuke Nakajima

A 5 GHz-band SiGe-MMIC direct quadrature modulator using a doubly stacked polyphase filter

A 5 GHz-band SiGe-MMIC direct quadrature modulator using a doubly stacked polyphase filter (PPF) is described. The doubly stacked PPF can dramatically reduce the output phase and magnitude imbalance corresponding to the transmission line length inside the RC PPF networks. The quadrature modulator using two-stage doubly stacked PPF performs the error vector magnitude of 3.6 %rms, magnitude error of 3.0 %rms, and phase error of 1.2 deg at LO frequency of 5.8 GHz for /spl pi//4-shifted QPSK (2 Msps) modulated signals. Wideband characteristics from 5.0 to 6.5 GHz are also demonstrated. This modulator dissipates 11.3 mA at 3.3 V supply voltage.

5.8GHz ETC SiGe-MMIC Transceiver having Improved PA-VCO Isolation with Thin Silicon Substrate

A fully integrated SiGe-MMIC transceiver having a power amplifier (PA), a transmit/receive switch (T/R SW), and a voltage controlled oscillator (VCO) is developed for electric toll collection system (ETC) terminals. To improve the isolation between the PA and the VCO, the back-polish technique of the silicon substrate (127mum thickness) is employed. Electro-magnetic simulation shows that a MMIC of 127mum thickness achieves the isolation improvement of 12.3dB compared with that of conventional 300mum thickness. As a result, the USB/LSB unbalance of the transmitted amplitude shift keying (ASK) signal can be reduced from 4.2dB to 1.2dB at 13dBm output power. The MMIC transceiver fabricated in 0.35mum SiGe BiCMOS process achieves the maximum output power of 15.5dBm with the adjacent channel power ratio (ACPR) of -33.5dBc

A 5GHz-band SiGe-MMIC quadrature modulator using a circular polyphase filter for 1Gbps transmission

A 5GHz-band SiGe-MMIC direct conversion quadrature modulator using a circular polyphase filter for high data rate is described. High I/Q vector accuracy is achieved using a circular polyphase filter with a completely symmetric layout as a 90 degrees LO power divider. By combining high cut-off frequency baseband amplifiers and broad-band unit mixers, a fabricated quadrature modulator shows the EVM of 3.3% rms at 5.5 GHz using 64-QAM OFDM signals with the channel bandwidth of 204 MHz, which corresponds to the data rate of 1.161 Gbps.

0.8-5.2GHz band SiGe-MMIC Q-MOD for multi-band multi-mode direct conversion transmitters

In order to realize multiband multimode transmitters for the 4th generation mobile communication systems based on software define radio (SDR) technology, 0.8-5.2GHz broad-band direct conversion quadrature modulator (Q-MOD) has been fabricated in 0.35/spl mu/m SiGe BiCMOS process. The circuit combination of a static frequency divider and a poly phase filter (PPF) enables higher 90degree phase accuracy than that of the static frequency divider alone. By employing this 90 degree power divider, the fabricated Q-MOD achieves EVM of 4.0/3.1% rms at 0.8/2.1GHz W-CDMA transmission and 2.5% rms at 5.2GHz wireless-LAN (IEEE 802.11a) transmission.

0.8-5.2 GHz band SiGe-MMIC Q-MIX for a multi-band multi-mode direct conversion receiver

By employing a 14 GHz static frequency divider and broadband SiGe-HBT unit mixers, a 0.8-5.2 GHz band Q-MIX is developed using a 0.35 /spl mu/m SiGe BiCMOS process. The fabricated Q-MIX has constant conversion gain (Gc) over the wide baseband (BB) frequency range up to 100 MHz and performs good I/Q balance (<0.17 dB, <3.6 degrees) over the wide RF frequency range of 0.8-5.2 GHz.

L-band glass-epoxy 5-bit phase shifter module using SW-bank chips and low cost L, C chips

A low cost L-band 5-bit phase shifter module is described. This module is fabricated on a glass-epoxy substrate, and consists of GaAs SW-bank chips and high/low pass filters for phase shift circuits made up of chip inductors/capacitors. The fabricated module shows comparable features in size and RF performance to those of MMIC in a ceramic package.

A 5GHz-band SiGe-MMIC transceiver for 324Mbps transmission

A 5 GHz-band SiGe-MMIC transceiver for 324 Mbps transmission is developed. The broadband transceiver characteristics are obtained by utilizing a 5 GHz- band Q-MOD with a circular polyphase filter in the transmitter, and a broadband IFVGA and Q-MIX in the receiver. A developed SiGe-MMIC performs EVM of 3.3%rms and EVM of 5.9%rms in the transmitter and the receiver, respectively using 64-QAM OFDM signal with 120 MHz bandwidth, which corresponds to the data rate of 324 Mbps. Utilizing the developed SiGe-MMIC, the Hi-Vision streaming video data is transmitted without interruption, and is clearly projected onto the TV.

0.8-5.2 GHz band SiGe MMIC quadrature mixer for SDR direct conversion receivers

A 0.8-5.2 GHz broad-band quadrature mixer for SDR (software designed radio) direct conversion receivers has been developed using 0.35 /spl mu/m SiGe BiCMOS process. The quadrature mixer employs a high speed static frequency divider for a 90 deg LO power divider and broad-band SiGe HBT unit mixers. High speed operation of the static frequency divider is realized by adding 2-stage emitter follower to its output section. The fabricated quadrature mixer achieves an EVM of 3.1%rms for W-CDMA signals at 0.8 GHz and an EVM of 2.1%rms for W-LAN (IEEE 802.11a) signals at 5.2 GHz, respectively. It also has constant conversion gain over the wide base-band frequency range up to 500 MHz at RF frequency of 0.8 GHz.

X-Band SiGe-MMIC Low Noise Amplifier Using Low Parasitic Capacitance Via Holes for Emitter Grounding

An X-band SiGe-MMIC single-ended two-stage low noise amplifier (LNA) using low parasitic capacitance via holes for the emitter grounding is described. In order to obtain low impedance emitter/source ground of a silicon based single-ended amplifier, we have developed via holes which can be fabricated after the 0.35 mum SiGe-BiCMOS process. Since there are low resistivity epitaxial layers in the silicon substrate, the via hole has the large parasitic capacitance. By introducing deep trench isolations to separate the epitaxial layers around a via hole from the other area of the chip, the parasitic capacitance of a via hole can be reduced. A fabricated X-band single-ended two-stage LNA using the developed low parasitic capacitance via holes shows a gain of 21 dB, a noise figure of 4.8 dB, an IP1dB of -26 dBm at 11 GHz. The power dissipation of the circuit is 19.1 mW at a 3.3 V supply voltage. The developed via holes can be useful for the silicon MMICs at the high frequency of X-band