Makio Komaru

A Ka-Band GaAs Power MMIC

A Ka-band GaAs power MMIC with source island via-hole PHS structure and monolithic power divider /combiner circuits was developed and reliability study was performed. This source island via-hole technique successfully reduced both thermal resistance and source parasitic inductance of the MMIC. The 3200 µm MMIC gave power output at 1dB gain compression of 1.1 W, linear power gain of 4.0 dB and power added efficiency of 10.8 % at 28 GHz. No failure was observed in the temperature cycling, the DC running and the high temperature storage tests.

A novel FET structure of buried plated heat sink for superior high performance GaAs MMICs

A novel FET structure with buried plate heat sink is proposed which gives higher power output and power added efficiency with easy wafer and chip handling. The substrate thickness is extremely thin (30 mu m) with a 70- mu m-thick gold-plated heat sink for the FET region, and it is 100- mu m for the remaining part of the chip. The buried plated heat sink FET with a gate width of 350 mu m provides a superior low thermal resistance of 16 degrees C/W, a power output as high as 27.9 dBm with an excellent power added efficiency of 32% at 1-dB compression point, and a linear power gain of 8.3 dB at 18 GHz. The fabrication technique, the structural reliability, the thermal resistance, and the RF performances of the newly developed FETs are presented.<<ETX>>

High gain and high efficiency K-band power HEMT with WSi/Au T-shaped gate

We have developed WSi/Au T-shaped buried gate pseudomorphic HEMT with the good uniformity of recess current by using a selective etching process and with a high off-state break down voltage of over 19 V. A 1.4 W output power has been obtained with a power-added efficiency of 55.6% and an associated gain of 9.2 dB under high voltage operation of Vd=10 V at 18 GHz. This is the highest gain and efficiency achieved by a single FET chip with over a watt output power at this frequency.

A Ka-band direct oscillation HBT VCO MMIC with a parallel negative resistor circuit

This paper describes a low phase noise Ka-band VCO MMIC employing InGaP/GaAs HBT processes. The VCO has the following two features: a novel circuit comprising negative resistors arranged in parallel that achieves a steep phase slope, and a tuning circuit with two resonators that offers a wide tuning range and steep phase slope. Measurement results of the developed VCO show a phase noise ranging from -111 to -114 dBc/Hz at an offset frequency of 1 MHz, and a tuning bandwidth above 1.1 GHz in a 38-39 GHz band.

A 3.3V, 1W GaAs One-Chip Power Amplifier MMIC for Cellular Phones

A 900-MHz-band 1W one-chip power amplifier MMIC, which operates at the low-supply voltage of 3.3 V and includes all bias and output matching circuits, has been developed for cellular phones. It is capable of delivering output power over 1.1 W with a power added efficiency of 43% at 3.3 V. With its extremely small chip size of 2.5 mm × 3.48 mm, it is less than one fifth the size of previously reported multi-chip ICs (MCICs). This new MMIC, the characteristics of which are compared with those of the existing MCICs, can be expected to contribute to the realization of smaller, lighter-weight cellular phones.

A 19 GHz low phase noise HFET VCO MMIC

A 19 GHz extremely low phase noise voltage controlled oscillator (VCO) MMIC is presented. To reduce the phase noise of the VCO, a heterostructure field effect transistor (HFET) is used as the active device, because its low frequency noise properties are superior to that of high electron mobility transistors (HEMT). This VCO showed a typical phase noise of -120 dBc/Hz at 1 MHz offset from the carrier. This performance is better than other VCOs operating above 10 GHz. The measured tuning range is 400 MHz and output power is 2 dBm. The fabricated MMIC chip size is 2.7 mm/spl times/1.4 mm.

A 50% PAE K-Band Power MMIC Amplifier

This paper describes the successful development of a 2-stage power amplifier (PA) with 50% efficiency at K-band. A 3-stage variable gain amplifier (VGA) was also developed for a driving stage. Metal - Insulator - Metal (MIM) capacitors and high impedance lines are employed as matching elements to accomplish a compact chip size. As a result, these amplifiers achieve compact chip sizes of 1.0 × 2.0 mm2. In designing the PA, gate widths in the first and second stages are optimized to achieve high efficiency. The PA and VGA have linear gains of more than 18 dB and 24 dB from 18 GHz to 20 GHz, respectively. The PA delivers an output power of 24.6 dBm and a power added efficiency (PAE) of as high as 50% at 19 GHz. To our knowledge, this is the highest PAE at K-band. These results are promising for onboard light weight Active Phased Array Antenna (APAA) at K-band.

A V-band monolithic InP HEMT resistive mixer with low LO-power requirement

We report on a 60 GHz-band InP HEMT resistive mixer that can be operated with very low LO-power. The mixer is fabricated using Coplanar Waveguide (CPW) techniques to reduce production costs. A narrow source-to-drain space and a short length gate (0.15 /spl mu/m) are employed in order to reduce the LO-power requirement. The minimum conversion loss of 8.4 dB is achieved at a 55 GHz RF frequency with LO power of -2 dBm. This low LO-power is comparable with the best data ever reported for millimeter-wave passive mixers. In addition, the mixer has an excellent IF output linearity that indicates capability to provide good intermodulation performance.

A short stub matching 77 GHz-band driver amplifier with an attenuator compensating temperature dependence of a gain

This paper describes a 77-GHz three-stage driver amplifier integrated with a very compact 4-dB digital attenuator. The attenuator can provide successful suppression in the gain variation of the amplifier according to ambient temperature in practical use. In addition, the amplifier matching fashion using short stubs and series transmission lines helps suppress unwanted transducer gain and return gain in the out-of band of lower than 77 GHz. The amplifier fabricated in pseudomorphic high electron-mobility technology can deliver a gain of 17.9 dB with an input return loss of 21.0 dB and an output return loss of 22.7 dB in the 77-GHz band, while keeping lower than -16.5dB of gain in the out-of band. Over the temperature range from -20/spl deg/C to 100/spl deg/C, the measured results show that a gain variation of less than 2.0 dB is achieved by using the attenuator, while the gain variation without the attenuator is as large as 6.0 dB. The die size is as small as 2.3/spl times/1.4 mm/sup 2/ due to the very compact attenuator of a 0.2/spl times/0.6 mm/sup 2/ occupied area.

A 20 GHz MOD-made BST thin film tunable phase shifter for phase adjustment of digital 360-degree PHEMT phase shifter

We have newly designed and fabricated both Ba x Sr 1-x TiO 3 (BST) ferroelectric thin film tunable phase shifter and pseudomorphic HEMT MMIC digital 360-degree phase shifter. A low loss BST thin film was obtained on MgO substrate by preparation of initial layer by pulsed laser deposition (PLD) and following metal-organic-decomposition (MOD) method. For the interdigital capacitors with finger spacing of 10 μm, dielectric loss was found to be as low as 0.002 to 0.004 when applied surface electric field was from m40 to ±40 kV/cm at measuring frequency of 1 MHz, where tunability was about 12%. Moreover, it increases up to about 40% in a Pt/BST/Pt stacked capacitor structure when the applied electric field was from m170 to ±170 kV/cm at the same frequency. When applying dc bias voltage of 0 to 60 V to the electrodes of the CPW pattern (width:60 μm, gap:10 μm, length:2.5 mm), a differential phase shift of 18 degree was obtained at 20 GHz with insertion loss of about -2 dB for Au/Cr interconnection. A 3-stage LC-ladder-type phase shifter with variable capacitors of BST film was designed to have a differential phase shift of about 40 degrees at 20 GHz. A fabricated phase shifter shows successfully the shift of 40 degree at 20GHz with bias of 60 V. The HEMT MMIC also shows a digital 360-degree phase shift with 11.25 degree interval, thus the BST phase shifter can be usable for phase adjustment of the MMIC. Finally it is found that the new BST film process is very promising for realizing a micro and millimeter-wave tunable device.