Low-power technology for front-end GaAs ICs and hybrid IC (HIC) for a mobile communication equipment will be presented. For low-power operation of GaAs front-end ICs, new techniques of the intermediate tuned circuits, the single-ended mixer, dualgate MESFETs, and the asymmetric self-aligned LDD process were investigated. The designed down-converter IC showed conversion gain of 21 dB, noise figure of 3.5 dB, 3rd-order intercept point in output level (IP3out) of 4.0 dBm, image-rejection ratio of 20 dB at 880 MHz, operating at 3.0 V of supply voltage and 5.0 mA of dissipation current. The down-converter IC was also designed for 1.9 GHz to obtain conversion gain of 20 dB, noise figure of 4.0 dB, IP3out of 4.0 dBm, image-rejection ratio of 20 dB at 3.0 V, 5.0 mA. The up-converter IC was designed for 1.9 GHz using the same topology of circuit and showed conversion gain of 15 dB, IP3out of 7.5 dBm, and 1 dB compression level of -8 dBm with -20 dBm of LO input power, operating at 3.0 V, 8.0 mA. Another approach to the low-power operation was carried out by HIC using the GaAs down-converter IC chip. The HIC was designed for 880 MHz to show conversion gain of 27 dB, noise figure of 3.3 dB, IP3out of 3.0 dBm, image-rejection ratio of 12 dB, at 2.7 V, 4.5 mA. The HIC measures only 8.0 mm6.0 mm1.2 mm.

Highly miniaturization technology in front-end GaAs Hybrid IC for mobile communication equipment will be presented. A combination of MBB (micro bump bonding) technology and the new GaAs IC fabrication process using high dielectric constant (εr) thin film technology has achieved a super small HIC with low cost and low power consumption. The new HIC was constructed of only a ceramic substrate in which the spiral inductors were formed on it and the GaAs IC chip that was bonded by using MBB technology. The MBB technology lead the HIC to a lower temperature process without soldering, a smaller bump diameter, at shorter intervals and the lowest parasitic in the bump. The advantage of the small bonding pad of the IC contributes to miniaturize the IC chip and reduces the chip cost. The GaAs IC process technology using high-εr thin film achieves the integration of all capacitors in the IC without increasing the chip size. Furthermore, low power consumption was achieved by 0. 5-µm LDD BP-MESFET with a high k-value. Although capacitors were integrated on the IC, all of the inductors were formed on the top of the ceramic substrate using a thin film metal process. This was used due to its large occupation area when it was integrated on the IC, and produced a low Q-factor. As a results, the chip was minimized to a size of 0. 81. 0 mm2 and achieved a low-cost chip. Two types of HICs were fabricated for 880 MHz cellular band and 1. 9 GHz PHS (Personal Handy phone System) band. The HIC at 880 MHz measures only 5. 05. 01. 0 mm3, and offered a conversion gain of 25 dB, a noise figure of 4. 2 dB and an image rejection ratio of 12 dB at 2. 7 V and at a power supply of 3. 5 mA. The HIC for 1. 9 GHz measures only 3. 54. 01. 0 mm3, and showed a conversion gain of 16. 0 dB, a II P3 of -16. 0 dBm, and an image rejection ratio of over 20 dBc at 3. 0 V and at power supply of 4. 5 mA.

A three-mode switched-LNA has been developed using a 0.25 µm SiGe BiCMOS technology. The LNA features low noise figure (NF) performance, while achieving both low dissipation power and low distortion characteristics. The proposed MOSFET switch incorporating a newly developed switch circuit with a triple-well structure, which changes the LNA's mode, provides a parasitic capacitance of just 0.52 times that of a conventional MOSFET switch. This results in a significant NF improvement, by 0.16-0.33 dB, for the three-mode switched-LNA compared to a conventional LNA. Extensive studies of the MOSFET switch with regard to the structural parameters and the doping profiles are reported. Experimental results and the overall performance of a trial IC incorporating the three-mode switched-LNA are also given.

Low-voltage technology in front-end GaAs IC for mobile communication equipment will be presented. New techniques in combination with different threshold voltage (Vth) FETs for an amplifier and a mixer were investigated for low-voltage operation of the IC. The amplifier and mixer consist of a cascode connected to FETs with shallow and deep Vth. The best suitable distribution of the supply voltages was accomplished for each FETs by using a combination of different Vth, and excellent RF characteristics of the IC were obtained, even at low voltage operation. In addition, this front-end IC has a high image rejection ratio (IRR) without using an external image rejection filter, but by using high Q-value input and intermediate matching circuits. The fabrication process used an asymmetric self-aligned BP-LDD process and high dielectric constant (high-εr) on-chip bypass capacitors using SrTiO3 contributed to a reduction in dissipation current, chip size and parasitic reactance in the source wires. The fabricated IC showed a conversion gain (CG) of 23 dB, noise figure (NF) of 2.8 dB, 3rd order output intercept point (IP3out) of 3 dBm, image rejection ratio (IRR) over 20 dBc and LO to RF isolation over 25 dB, operating by 1.0 V single supply with dissipation current of 6.8 mA at 880 MHz. At 1.9 GHz, the IC also showed excellent RF characteristics with dissipation current of 6.5 mA at 1.0 V. The IC die is very small the size is 0.75 mm0.75 mm, and is molded in a mini-6pin plastic package.