Masaaki Soda

A 60-GHz f/sub T/ super self-aligned selectively grown SiGe-base (SSSB) bipolar transistor with trench isolation fabricated on SOI substrate and its application to 20-Gb/s optical transmitter ICs

A 60-GHz cutoff frequency (f/sub T/) super self-aligned selectively grown SiGe-base (SSSB) bipolar technology is developed. It is applied to 20-Gb/s optical fiber transmitter ICs. Self-aligned bipolar transistors mutually isolated by using a BPSG-filled trench were fabricated on a bond-and-etchback silicon-on-insulator (SOI) substrate to reduce the collector-substrate capacitance C/sub CS/. The SiGe base was prepared by selective epitaxial growth (SEG) technology. A 0.4-/spl mu/m wide emitter was used to reduce the junction capacitances. The maximum cutoff frequency f/sub T/ and the maximum frequency of oscillation f/sub max/ were 60 and 51 GHz, respectively. By using this technology, Si-ICs for an optical transmitter system were made, such as a selector (a multiplexer without input and output retiming D-type flip-flops (D-F/Fs)), a multiplier, and a D-F/F. An internal high-speed clock buffer circuit achieves stable operation under a single clock input condition in the selector and the multiplier ICs. Their stable operation was confirmed up to 20 Gb/s. The selector IC for data multiplexing operates at over 30 Gb/s.

A 2.4 Gb/s receiver and a 1:16 demultiplexer in one chip using a super self-aligned selectively grown SiGe base (SSSB) bipolar transistor

This paper reports a 2.4 Gb/s optical terminal IC that integrates high-speed analog and digital circuits for future optical networks using 60-GHz f/sub T/ self-aligned silicon-germanium (SiGe)-alloy base bipolar transistors. The selective epitaxial growth (SEG) SiGe base was formed by using cold-wall ultra-high vacuum (UHV)/CVD technology. Boron concentration reduction at the SiGe epitaxial layer/Si-substrate interface by using a new treatment prior to SEG leads to electrical characteristics with less dependence on bias voltage. The IC consists of a receiver (a preamplifier, an automatic gain control (AGC) amplifier, a phase-locked loop (PLL), and a D-type flip-flop (D-F/F)), and a 1:16 demultiplexer (DMUX). An input offset control circuit is included in the AGC amplifier for wide dynamic range. Trench isolation and silicon-on-insulator (SOI) technologies are introduced to reduce crosstalk between the amplifiers and the PLL. Power consumptions are 0.6 W at -5.2 V for the analog part and 0.45 W at -3.3 V for the digital part, which does not include the ECL output buffers.

A self-aligned SiGe base bipolar technology using cold wall UHV/CVD and its application to optical communication ICs

A self-aligned SiGe base bipolar technology and its application to optical communication ICs are presented. Using cold wall ultra-high vacuum (UHV)/CVD technology, a self-aligned selective SiGe/Si epitaxial growth can be realized for the overhanging structure of the base electrode polysilicon. This is a novel self-aligned bipolar transistor, which we call a super self-aligned selectively grown SiGe base (SSSB) bipolar transistor. The maximum cut-off frequency f/sub T/ of 60 GHz and the maximum frequency of operation f/sub max/ of 50 GHz have been obtained. This technology has been applied to optical communication ICs. A receiver and a transmitter ICs fabricated on a silicon on insulator (SOI) substrate stably operate at up to 20 Gb/s.

Monolithic ultra-broadband transimpedance amplifiers using AlGaAs/GaAs heterojunction bipolar transistors

Monolithic ultra-broadband transimpedance amplifiers are developed using AlGaAs/GaAs HBTs. To realize good amplifier performances, two factors are mentioned: an affordable HBT fabrication process using the self-aligned method and an optimized circuit design considering large signal operations. The developed HBT fabrication process achieves excellent uniformity in DC characteristics and the effect on amplifier microwave performances, derived from the discrete device uniformity, is estimated. Amplifier circuit configurations are designed by harmonic balance simulation using the extracted large signal device parameters The fabricated amplifier exhibits a DC to 13.4-GHz bandwidth with an 18.1-dB gain. Fairly good uniformity is also achieved for the amplifier microwave performances. An optical receiver module is constructed mounting the developed HBT amplifier and InGaAs p-i-n photodiode chips. The optical receiver module provides a 9.4-GHz bandwidth and an optical receiver sensitivity of /spl minus/15.7 dBm at 10-Gb/s data rate. >

On-chip sine-wave noise generator for analog IP noise tolerance measurements

A sine-wave noise generator with a harmonic-eliminated waveform is proposed for measuring the noise tolerance of analog IPs. In the waveform, harmonics up to the thirteenth harmonic are eliminated by combining seven rectangular waves with 22.5-degree spacing phases. This waveform includes only high-region frequency harmonic components which are easily suppressed by a low-order filter. In the circuit, the harmonic-eliminated waveform generator is combined with a current-controlled oscillator and a frequency-adjustment circuit. The sine-wave noise generator can generate power-line noise from 20 MHz to 220 MHz in 1 MHz steps. A spurious-free dynamic range (SFDR) of 45 dB is obtained at the 100 MHz noise frequency.

The optical terminal IC: A 2.4 Gb/s receiver and a 1:16 demultiplexer in one chip

This paper reports the 2.4 Gb/s optical terminal IC integrating high-speed analog and digital circuits for future optical networks. The IC consists of a receiver (a preamplifier, an automatic gain control (AGC) amplifier, a phase-locked-loop (PLL), a D-F/F), and a 1:16 demultiplexer (DMUX). An input offset control circuit is included in the AGC amplifier for wide dynamic range. The trench isolation and SOI technologies are introduced to reduce the crosstalk effect between the amplifiers and the PLL.