Shry-Sann Liao

A novel compact-size branch-line coupler

A novel compact-size branch-line coupler without any implementation of lumped-elements, bonding wires, and via holes is proposed. In this study, the size of the proposed coupler occupied only 45% of the conventional branch-line coupler at 2.4GHz. The performances of the circuit can be competed with the conventional coupler. The element sizes of this coupler can be realized easily by using simply standard printed-circuit-board etching processes. It is very useful for applications in the wireless communication systems.

Compact Planar Microstrip Branch-Line Couplers Using the Quasi-Lumped Elements Approach With Nonsymmetrical and Symmetrical T-Shaped Structure

A class of the novel compact-size branch-line couplers using the quasi-lumped elements approach with symmetrical or nonsymmetrical T-shaped structures is proposed in this paper. The design equations have been derived, and two circuits using the quasi-lumped elements approach were realized for physical measurements. This novel design occupies only 29% of the area of the conventional approach at 2.4 GHz. In addition, a third circuit was designed by using the same formula implementing a symmetrical T-shaped structure and occupied both the internal and external area of the coupler. This coupler achieved 500-MHz bandwidth while the phase difference between S21 and S31 is within 90degplusmn1deg. Thus, the bandwidth is not only 25% wider than that of the conventional coupler, but occupies only 70% of the circuit area compared to the conventional design. All three proposed couplers can be implemented by using the standard printed-circuit-board etching processes without any implementation of lumped elements, bonding wires, and via-holes, making it very useful for wireless communication systems

A Microcontroller Instruction Set Simulator for EMI Prediction

This paper predicts programspsila effect of time-domain electromagnetic interference (EMI) on a simple microcontroller. Using the instruction current concept and a modified instruction set simulator (ISS) for this purpose, this paper can predict, in the time domain, accurate conducted EMI behaviors when different programs are running on this system. Different program codespsila EMI behaviors are predicted, and all of these codes fit well with the measurement results. The modified ISS is adapted to estimate the pipeline effect of a microcontroller and to give an accurate current profile of any complex multi-instruction program. By using the instruction current model and the proposed ISS, this paper can predict the EMI behavior of a very complex program-a simple home-made operating system (OS) kernel. To the best of our knowledge, this paper is the first work on observation and prediction of EMI behavior of an embedded system OS kernel.

Novel reduced-size coplanar-waveguide bandpass filter using the new folded open stub structure

Proposes a novel folded skill and a simpler method than that of older methods. The advantages of this new structure reveals a better skirt factor than that of the conventional folded /spl lambda//4 series open stub, and it reduces the folded area of the conventional structure by at least 50%. Besides, by using the new folded /spl lambda//4 open stub to realize a bandpass filter, the size of the circuit will be reduced greatly and achieve better stopband rejection.

Detection of Electromagnetic Interference in Microcontrollers Using the Instability of an Embedded Phase-Lock Loop

This paper presents a combined hardware-software mechanism for the detection of electromagnetic interference of a microcontroller (μC) in daily usage. This detection mechanism is based on the instability of phase-lock loop embedded in the target μC. It can detect the presence of EMI with higher sensitivity than polling the hardware status of the μC internal registers and thus provides a better detection margin within the 10 kHz to 1 GHz EMI frequency range. Despite its relative slowness and its resource consumption, it is very robust, can be implemented in virtually any application software, and does not require any electromagnetic compatibility test equipment.

Novel design for small-size coplanar waveguide frequency tripler

This letter presents a novel design for a small-size coplanar waveguide frequency tripler. In this study, a new BPF has been replaced the conventional stub lines in the output termination of the multiplier. Not only enhance the performance of the tripler, but also reduce the whole circuit size. to 2.125/spl times/2.275 cm/sup 2/ in the frequency 0.8/2.4 GHz, The spurious suppressions are 37.48, 33.38, and 32.08 dBc for the 1st, 2nd, and 4th harmonics, respectively. It reveals the best output power of -1.92 dBm for a 0 dBm input signal and maximum conversion gain of -1.92 dB. It is very useful for applications in the wireless communication and radar systems.

Eliminating the Reverse Charge Sharing Effect in the Charge-Transfer-Switch (CTS) Converter

A novel voltage level controller for low-power charge pump converters will be presented in this paper. The proposed voltage level controller would react according to the pumped voltage in the charge-transfer-switch (CTS) converter. For the CTS circuit, the pumping operation would be degraded by the charge sharing effect in the auxiliary switch path. In this study, a voltage shifter was used as the voltage level controller to overcome this serious problem without consuming too much chip area. The simulation results showed that the converter can accept a rated input of 1.5V and generated an output up to 8V based on the TSMC 0.35-µm CMOS technology. The layout consumed an area of 125*160µm2. The highest output obtained in measuring the real chip was 5.5V which is primarily due to the limitation that the transistor could tolerated. The largest load was estimated as high as 6mW which is large enough for on-chip application.

On LA code performance analysis for LAS-CDMA communications

Having investigated LA code construction, a method of triangular array formations of correlation value distribution positions for 16- and 17-pulse LA code groups is proposed in an effort to have a further theory analysis of LA codes.

IC-EMC model extension based on internal impulse response function

This paper proposes a method for microcontrollers IC-EMC model extension. The internal impedance can be estimated without any prior knowledge of microcontroller. The internal impedance is represented by “impulse response” (IR) function and built into an extended IC-EMC model. Theoretical deduction, simulation, and a case study are presented in this paper. Currently, the case study shows that the proposed method is accurate within limited bandwidth (below 30 MHz) due to measurement limitations and is expected to be more accurate with more advanced equipments. This method can help IC design companies to keep their intellectual properties (IP) inside while providing an IP-unrelated EMC model for IC-EMC modellers. It can also help IC-EMC modellers to determine different ICs internal impedance by themselves.

FPGA programmable PLL impact on EMC behavior

This paper studies the impact of EMC on a programmable PLL feature of both FPGA-based IC and PIC series microcontroller (µC). We use ACTEL FPGA IC the target IC and design the testing board according to IEC standard. By using the TEM-CELL method to measure the electromagnetic radiation from the circuit board, different PLL EMC behaviors of the PIC µC with the FPGA-based design are compared. Generally, the EMC effect of FPGA is worse than that of the commercial PIC µC. Among all of the measurement results, it shows that the different PLL output frequency setups have different and crucial EMC impact.