In this work, using 0.2 µm GaAs modulation doped FET (MODFET), a high performance downconverter MMIC was developed for direct broadcasting satellite (DBS) applications. The downconverter MMIC showed a noise figure of 4.3 dB which is lower by 5 dB than conventional ones, and required only a low LO power of -10 dBm for normal DBS operation. At a low LO power of -10 dBm, the power consumption was 175 mW, which is lower than 50 percent of conventional ones. The frequency response of conversion gain exhibited a low gain ripple of 0.9 dB, and the LO leakage power was suppressed to a lower value than -30 dBm under a LO input power of -10 dBm. The fabricated chip exhibited a small size of 0.840.9 mm2. The objectives of this work are to improve the traditional direct broadcasting satellite (DBS) downconverters by an efficient circuit design and to describe the techniques employed in the design.

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.

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.

A MMIC power amplifier operating with a single-supply (3.0 V) has been developed for 5.8 GHz Japanese Electronic Toll Collection (ETC) System. The present MMIC contains two FETs, matching circuits (input, intermediate and output matching circuits), and two drain bias circuits. High dielectric constant material SrTiO3 (STO) is used for by-pass and input coupling capacitors. Very small die size of 0.77 mm2 has been realized by using the STO capacitors and negative feedback circuit technology. High 1 dB output gain compression point (P1dB) of 13 dBm, high gain of 21.4 dB and low dissipation current of 41.3 mA have been achieved under 3.0 V single-supply condition.

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.