Jin-Sup Kim

MAGIC3D simulation of an ultra-compact, highly efficient, and high-power reltron tube

In this paper, we use a three dimensional particle-in-cell (PIC) code, MAGIC3D, to investigate the operating characteristics of an ultra-compact, high power reltron tube with self-modulation beam and post-acceleration of modulated beam. The simulation model is a full 3D model because the reltron is intrinsically a three-dimensional problem due to the asymmetrical geometry of the modulating cavity. In the reltron, the mode of operation is ¿/2-mode, providing the means to modulate an electron beam in short distances. Simulations show that ultra-compact reltron with a beam voltage of 120 kV and an acceleration voltage of 800 kV generates 38.3 MW high power microwave at 2.887 GHz with an electronic efficiency of 52.7%.

A Novel Broadband Suspended Substrate Stripline Filter using Resonators with T-shaped Open-Circuited Stubs

A novel broadband suspended substrate filter is proposed and implemented using a shielded suspended substrate stripline (SSL), aiming at transmitting the signals in the passband of 6-10 GHz. It is composed of two quarter-wavelength resonators and K-inverter. The K-inverter is composed of two short-circuited stubs. After optimization of this filter, a good bandpass behavior with ten transmission poles is theoretically realized and experimentally confirmed. Within the whole BPF passband, the return loss is found better than 14 dB, and the insertion loss is less than 1.9 dB.

Design of a 3.5-GHz OOK CMOS transmitter with triangular pulse shaping

A low-power CMOS on-off keying (OOK) transmitter employing a triangular pulse shaping scheme is presented. The proposed pulse shaping circuit is based on a current-reused common-source stage, whose gain is controlled by modulating the gate-source voltage in a triangular form. The triangular control signal is generated by an opamp-based integrator. The proposed pulse shaping scheme can effectively support variable data rate. A 3.5-GHz OOK transmitter circuit adopting the proposed pulse shaping scheme is designed in a 0.13 μm CMOS process. It successfully modulates digital data from 100 kbps to 10 Mbps and delivers an output power of +2.5 dBm. The total current consumption is 4.17 mA from a 1.2 V supply voltage, of which only 0.57 mA is dissipated at the transmitter core excluding the output buffer.

Novel broadband suspended substrate stripline filter using dual-mode resonators

A novel broadband suspended substrate filter is proposed and implemented using dual-mode resonator aiming at transmitting the signals in the passband of 10-18 GHz. It is composed of two quarter-wavelength resonators and inductor. The inductor is a short-circuited stub. After optimization of this filter, a good bandpass behavior with ten transmission poles is theoretically realized and experimentally confirmed. Within the whole BPF passband, the return loss is found better than 10 dB, and the insertion loss is less than 1.9 dB.

ASIC design of DMPPT control for photovoltaic systems

This paper presents ASIC design of Distributed Maximum Power Point Tracking (DMPPT) control for photovoltaic systems. This approach enables lower cost solution compared to a microprocessor-based solution. Functionality and performance of the MPPT algorithm selected was verified first by simulation and secondly by real-time testing using a FPGA, a PV emulator, an electronic loader and a DC-DC converter. A 0.35um 1-poly 3-metal 3.3V process was selected for the ASIC development. MPPT peak efficiency of over 98% is achieved.

IC design of DMPPT controller for Cascade and MCCU topology of photovoltaic systems

This paper presents IC design of Distributed Maximum Power Point Tracking (DMPPT) controller for Cascade and Mismatched Current Compensation Unit (MCCU) for photovoltaic systems. The Cascade part can handle the conventional DMPPT algorithm and the MCCU part can handle the differential power processing algorithm. This solution can mitigate mismatches in photovoltaic(PV) power system, while introducing no insertion loss and reducing the system cost compared to a microprocessor-based solution. A 0.18um 1-poly 4-metal 5V process was selected for the IC development. MPPT peak efficiency of over 99% is achieved.