Mohamed Razman Yahya

Fabrication and Characterization of PZT Thin Film Capacitors for MMIC Applications

This paper reports on the use of thin lead zirconate titanate (PZT) films for monolithic microwave integrated circuit (MMIC) capacitors to replace existing materials for better size-reduction. The films were sputtered on Pt/Ti/SiO2 coated, undoped silicon wafers. Square Pt electrodes with sides ranging from 10 mum to 50 mum were patterned on the PZT layers to form the capacitors. Results of this study show that PZT thin films can be utilized for efficient size reduction in MMIC. The linewidth obtained for a 50 Omega transmission line is merely 300 nm - this results in a size reduction of approximately five times compared to conventional MMIC. For a 50 times 50 mum electrode area, capacitance values ranging from 5 to 20 pF were obtained at frequencies up to 20 GHz. Suitable de-embedding of S parameters using Cascade microwave probes revealed films with relative permittivities of the order of 100 to 500

Design Of Experiment (DOE) For Thickness Reduction Of GaAs Wafer Using Lapping Process

This paper report a statistical method of performing wafer lapping experimental using design of experiment (DOE) technique in order to get best lapping time to reduced thickness of GaAs wafer. Lapping speed, lapping time, oscillator speed and weight was selected as four main factor determine the shortest time of thickness reduction. A complete 2 4 factorial of 4 factors (16 run) was design to determined the effect of selected factor. The lapping process was carried out using ULTRATEC Lapping& Polishing machine while the wafer thickness was characterized using Logitech non contact gauge. It was found that best lapping parameter was using lapping speed at 3 r.p.m, oscillator speed at 2 r.p.m and 3 weight block for duration of 240 sec. This parameter is able to reduce 156 mum of wafer within 240 second without any crack problems and able to give good reference of reduction of GaAs wafer thickness process period.

The microstrip coupled line Bandpass filter using LTCC technology for 5GHz wireless LAN application

This paper presents a top-down design of the microstrip coupled line Band pass filter (BPF) embedded in low temperature co-fired ceramic (LTCC) for 5 GHz wireless LAN applications. It includes the design, simulation, fabrication and measurements. The filter circuit was designed and simulated based on Agilent Advanced Automation (ADS2005A) software. Then, the physical dimensions of components and the filter itself is subsequently determined and the physical design is later performed in the layout window of Empire XcCEL. All measured simulations are analyzed and compared to design specifications and characteristics (curve fitting). Any inaccuracy is taken into account where corrected design is further recovered.

An LTCC design technique based on FDTD EM simulations

This paper described the Low Technology Co-fired Ceramic (LTCC) design methodology at TMRND based on FDTD EM simulations that are required when designing the RF/microwave circuit. In this paper, 3D EM analysis and optimization with Finite Different Time Domain (FDTD) software Empire XcCeltrade from IMST was applied to achieve accurate modeling of the RF/microwave circuit using LTCC technology. A multilayer spiral inductor was selected for discussion to show this LTCC design technique. The main elements of the LTCC design technique relies on three important guidelines; use accurate component models, link the circuit schematic to the layout to reduce errors and finally link the layout to an EM simulator to detect coupling problems.

Effect of Laser Bias Current to the Third Order Intermodulation in the Radio over Fibre System

Third order intermodulation (IM3) can cause non-linearity effects which result in interference and crosstalk between the subcarriers in radio over fibre (ROF) transmissions. This paper presents the experimental results of the effect of varying the magnitude of the laser bias current on the IM3 in an ROF system with direct modulation. We also investigate the behaviour of the system spurious free dynamic range (SFDR) with the bias current variation. The results show that there will be an optimum bias current range for a given range of the radio frequency (RF) input power in order to minimise the IM3 effect and obtain the best possible SFDR for the system

Adopting Electroabsorption Modulator for the WLAN 802.11a Radio over Fibre System

This paper presents the evaluation of radio over fibre (ROF) capability with electroabsorption modulator (EAM) as a downlink photodetector (PD) and uplink radio frequency (RF) modulator. The results show that the EAM device has potential to be adopted as the transceiver at the remote antenna unit (RAU) for the system. The 130 m ROF system with biased EAM is capable to obtain a symmetrical WLAN 802.11a data rate of 18 Mbps with laser diode output power of 8.7 dBm.

The study of etching selectivity between InGaAs and AlGaAs in acid based etching solution

The etching selectivity of AlGaAs and InGaAs was studied and analyzed. Different chemical solutions and compositions were varied to study the etch rate effect between these two materials. The etching rates and selectivity of the H/sub 3/PO/sub 4/:H/sub 2/O/sub 2/:H/sub 2/O, H/sub 2/SO/sub 4/:H/sub 2/O/sub 2/:H/sub 2/O and C/sub 6/H/sub 8/O/sub 7/:H/sub 2/O/sub 2/ is compared. The results show that the C/sub 6/H/sub 8/O/sub 7/:H/sub 2/O/sub 2/ chemical solution exhibits higher etch rate and significant selectivity in comparison with H/sub 3/PO/sub 4/:H/sub 2/O/sub 2/:H/sub 2/O, H/sub 2/SO/sub 4/:H/sub 2/O/sub 2/:H/sub 2/O.

15 GHz SPDT switch design using 0.15 µm GaAs technology for microwave applications

In this paper, very low loss and high isolation single pole double throw (SPDT) switch design for microwave applications using pseudomorphic high-electron mobility transistor (pHEMT) is presented. The MMIC switch design is developed using a commercially available 0.15 mum GaAs pHEMT technology. At the operating frequency of 15 GHz, the SPDT switch has 1.89 dB insertion loss and 26.66 dB of isolation. It also demonstrates 28.8 dBm of input P1dB gain compression point (P1dB) and 25.9 dBm of output P1dB.

Designing 5GHz microstrip coupled line bandpass filter using LTCC technology

A top-down detail design of a 5 GHz micro strip coupled line band pass filter in LTCC is presented in this paper. LTCC, which stands for low temperature co-fired ceramic is especially used for wireless and high-frequency applications. Now, the importance of LTCC is becoming more prominent in views of the fact a lot organizations has been funding R&D-projects regarding this new technology that focuses on larger implementation of functionality in LTCC substrates. Although Malaysia is new to this technology, its industry has certainly high hopes on the LTCC innovation to make a breakthrough and contribute significant benefits to the technology, industry, market and also, the country itself. The filter circuit was designed and simulated by using ADS2005A. Then, the physical dimensions of components and the filter itself is subsequently determined and the physical design is later performed in the layout window of Empire XcCEL. All measured simulations are analyzed and compared to design specifications and characteristics (curve fitting). Any inaccuracy is taken into account where corrected design is further recovered.

Design of 2-stage medium power amplifier using 0.5 μm GaAs PHEMT for wireless LAN applications

This paper presents the design and fabrication of two-stage medium power amplifier (MPA) using 0.5 mum GaAs PHEMT technology for the wireless LAN applications. The die size of this amplifier is only 1.7 mm times 0.85 mm. At a supply voltage of 5.0 V and 5.8 GHz operating frequency, a 2-stage MPA achieves a linear gain (S21) of 16.39 dB, P1 dB of 20.18 dBm, power gain of 15.15 dB and the PAE of 25.29%.