Research Interests:
Power amplifier integrated circuit (10), comprising: a substrate (50); an electrically conductive layer (22); and a transistor formed on the substrate (50), said transistor having a collector (12), a base (16) and an emitter (14b); marked... more
Power amplifier integrated circuit (10), comprising: a substrate (50); an electrically conductive layer (22); and a transistor formed on the substrate (50), said transistor having a collector (12), a base (16) and an emitter (14b); marked by: a contact bump (20) directly arranged on the emitter (14b) to connect the emitter (14b) with the electrically conductive layer (22) for heat dissipation.
Research Interests:
We have developed a novel planar integrated antenna-mixer structure. The device is constructed in parallel stripline (PSS), and consists of an endfire Vee antenna, R.F. matching filter, SIS junction array and I.F. output filter/matching... more
We have developed a novel planar integrated antenna-mixer structure. The device is constructed in parallel stripline (PSS), and consists of an endfire Vee antenna, R.F. matching filter, SIS junction array and I.F. output filter/matching network, sandwiched between a thick dielectric substrate and a similar dielectric superstrate. Expressions have been developed for the propagation constants and losses of PPS in finite thickness dielectric, and these have been confirmed by scaled modelling experiments.
Research Interests:
The use of adaptive antennas in mobile communications base stations is self-explanatory. It offers the potential of increased spectrum efficiency, extended range of coverage and reduced delay spread. However, one major concern for... more
The use of adaptive antennas in mobile communications base stations is self-explanatory. It offers the potential of increased spectrum efficiency, extended range of coverage and reduced delay spread. However, one major concern for adaptive antenna system is the non-linearity effects of the RF/IF chain upon digital baseband beamforming network. The article investigates these effects on the performance of adaptive antennas
Research Interests:
A wireless transceiver module, which includes an antenna, a signal processing unit, and a shielding shell. An antenna for transmitting and receiving a radio frequency signal and having a signal point; a signal processing unit is coupled... more
A wireless transceiver module, which includes an antenna, a signal processing unit, and a shielding shell. An antenna for transmitting and receiving a radio frequency signal and having a signal point; a signal processing unit is coupled to the signal point for processing radio frequency signals, and having a radio frequency circuit coupled to the antenna, a first group for the frequency signal into a first RF signal and for converting a second radio frequency signal into a second baseband signal; an electromagnetic shield case is used to shield the ground plane and the signal processing unit as an antenna.
Research Interests:
A set of modified semiconductor equations is described together with novel algorithms for solving them. These ensure a well-behaved, guaranteed convergent solution for a steady-state semiconductor model. Examples results on the simulation... more
A set of modified semiconductor equations is described together with novel algorithms for solving them. These ensure a well-behaved, guaranteed convergent solution for a steady-state semiconductor model. Examples results on the simulation of a GaAs Dual Gate MESFET are given to demonstrate the efficiency of the new scheme.
Research Interests:
The authors consider the design of chokes and their performance. They present the design and test of an ultra-broadband choke. Measurements show that this choke is usable upto about 20 GHz. As it is cheap, compact and easy to use it is... more
The authors consider the design of chokes and their performance. They present the design and test of an ultra-broadband choke. Measurements show that this choke is usable upto about 20 GHz. As it is cheap, compact and easy to use it is suitable for satellite and mobile communication applications.
Research Interests:
With the increased demand on higher capacity and better services from mobile communications networks, the rise of an adaptive antenna in mobile communications base stations is seen as inevitable. This technique has the potential of... more
With the increased demand on higher capacity and better services from mobile communications networks, the rise of an adaptive antenna in mobile communications base stations is seen as inevitable. This technique has the potential of increased spectrum efficiency, extended range of coverage and higher data throughput. It has presented an incentive to further investigate hardware aspects in the realisation of these systems. One of the key components in an adaptive antenna system is the transceiver subsystem. This contribution investigates linearity aspects of the up- and down-conversion chain on the performance of adaptive antennas and suggests solutions to the non-linearity problems within an adaptive antenna system.
Research Interests:
Research Interests:
This paper presents design of CMOS CDC-based comparators with an optimum method to suppress dynamic offset for high-speed flash ADCs. The CDC-based comparators are introduced, analyzed, modeled and optimized. The experiment results have... more
This paper presents design of CMOS CDC-based comparators with an optimum method to suppress dynamic offset for high-speed flash ADCs. The CDC-based comparators are introduced, analyzed, modeled and optimized. The experiment results have verified the design optimization. Compared to the ADCs with random sizing CDC comparators, the dynamic performance in terms of SNR and SFDR has improved over 30% @ the signal frequency lower than 800MHz and over 140% @ the signal frequency higher than 800MHz.
Research Interests:
The effects of nonlinearity on the performance of adaptive array antennas has been presented. The feed forward linearisation technique is identified as the most suitable for mobile communication base station applications. This is because... more
The effects of nonlinearity on the performance of adaptive array antennas has been presented. The feed forward linearisation technique is identified as the most suitable for mobile communication base station applications. This is because that the large bandwidth requirement and multiple carrier operations at base stations. The effect of using linearised amplifiers in the communications system has also been briefly discussed.
Research Interests:
In a traditional Inverter Circuit, using parallel power MOSFETs is a common practice to improve the performance of the circuit. However, in a wireless power transfer system using magnetic resonance coupling technique, the method of... more
In a traditional Inverter Circuit, using parallel power MOSFETs is a common practice to improve the performance of the circuit. However, in a wireless power transfer system using magnetic resonance coupling technique, the method of parallel MOSFET would cause a lot of problems: the speed of the MOSFET converter would decrease; the switching loss would increase. The worst situation is that the switch would not be able to meet the operating frequency of the Magnetic Resonance system. As a result, we introduce the Multi-switch Method to solve the problem above. From simulation, this method could reduce the loss of an individual switch. In this paper, we design a multi-switch circuit, and compare it with the traditional inverter circuit in a magnetic resonance system. Then we analyzed the individual switch loss in these two circuits by a comparative experiment to verify the effectiveness of this new circuit. The result suggests that, this multi-switch circuit improve the individual performance of the switch, and reduce the voltage oscillating waveform of the switch significantly.
Research Interests:
' Media Tek Inc., Hsinchu, Taiwan, * NTHU, Hsinchu, Taiwan, ** Wireless ICs Inc., Irvine, CA, USA ... Abslrad - This paper presents B single-chip quad-band GShl/GPRS transceiver with fully-integrated VCOs in a 0.3Spm BiCMOS... more
' Media Tek Inc., Hsinchu, Taiwan, * NTHU, Hsinchu, Taiwan, ** Wireless ICs Inc., Irvine, CA, USA ... Abslrad - This paper presents B single-chip quad-band GShl/GPRS transceiver with fully-integrated VCOs in a 0.3Spm BiCMOS technology. The transceiver consists of an ...