A newly proposed coupled-line low-pass filter structure is firstly integrated into rat-race coupler design in this paper for size reduction and harmonic suppression. This low-pass filter is composed of dual parallel coupled-lines with one open stub at the end. By properly substituting this low-pass filter unit cell (LUC) for each one of the six λ/4 sections in the conventional rat-race coupler, significant size reduction and harmonic suppression can be achieved while the property of this proposed coupler remains comparable to the conventional one for the passband (f₀=0.9GHz) with 33% relative size. Transmission is suppressed below -20dB from 2.5GHz to 5.6GHz, including the third, fourth, fifth and sixth harmonics.

View full abstract

This paper presents an on-chip touch sensor readout circuit using charge pump based switched-capacitor scheme. For the proposed touch sensor readout circuit, the touch panel capacitance is directly converted into a voltage level by the switched-capacitor charge pump, which does not require additional signal conditioning for detection. The additional circuitry following the charge pump such as the comparator and flip-flop does not consume any static current. Therefore, the suggested touch sensor can lead to a compact and low power on-chip solution with fast detection time. The prototype circuit is fabricated using CMOS 0.35µm technology, where the consumption current is only 2.2µA.

View full abstract

To establish an RF power standard above 110GHz, we have developed a measurement system using a down-conversion mixer with a spectrum analyzer, and the conversion loss of the mixer was determined by the three-mixer method. This method measures the three transmission S-parameters (S₂₁) of three mixer pairs using a vector network analyzer. The experimental results proved that the three-mixer method can determine the conversion loss of mixers with an uncertainty of 0.5dB (level of confidence: 95%) in the entire range of the D-band. Using this uncertainty and the uncertainty of the spectrum analyzer, the proposed system can measure the RF power in the D-band with an uncertainty of less than 2.0dB.

View full abstract

In this work, a scheme of an equilateral triangle array digital direction finding system is proposed, which implements the online real-time direction finding task for an airborne system. The three-elements equilateral triangle array can be used for calibrating the channel errors and eliminating the DOA (direction of arrival) fuzzy problem of the two-elements linear array, which is greatly reduced the system complexity and suitable for portable requirement. At the same time, the project adopts field programmable gate array (FPGA) to process the sample data in parallel mode, including data quadrature demodulation and multiple signal classification (MUSIC) algorithm. The hardware implementation of MUSIC algorithm makes the system more flexible and faster than software implementation. The experimental results show that the deviation is less than 0.5 degrees with over 64 snapshots and the time is less 6ms with 256 snapshots, and then the program can complete the MUSIC algorithm accurately with high speed.

View full abstract

The specific on-resistance of non-uniform super-junction (SJ) trench metal-oxide semiconductor field-effect transistor (TMOSFET) is superior to that of uniform SJ TMOSFET under the same breakdown voltage. For the desired blocking voltage with 100-V, the electric field varies exponentially with distance between the drain and the source regions. The idea with a linearly graded doping profile is proposed to achieve a much better electric field distribution in the drift region. The doping concentration linearly decreases in the vertical direction from the N drift region at the bottom to the channel one at the upper. The structure modeling and the characteristic analyses for doping density, potential distribution, and electric field are simulated by using of the SILVACO TCAD 2D device simulator, Atlas. As a result, the specific on-resistance of 0.66mΩ·cm² at the class of 100V and 100A is successfully optimized in the non-uniform SJ TMOSFET, which has the better performance than the uniform SJ TMOSFET in the specific on-resistance.

View full abstract

The state of charge (SOC) estimation for electric vehicles (EVs) is important and helps to optimize the utilization of the battery energy storage in EVs. In this way, aging is also a key parameter impacting the performance of batteries. In this paper, a hybrid neural model is proposed for the SOC estimation of ZEBRA (Zero Emission Battery Research Activities) battery considering the aging effect through the state of health (SOH) and the discharge efficiency (DE) parameters. The number of hidden nodes in neural modules is also optimized using particle swarm optimization (PSO) algorithm. The SOC estimation error of the proposed system is 1.7% when compared with the real SOC obtained from a discharge test.

View full abstract

A CMOS wideband LNA with tunable and low-loss integrated TX leakage canceller is presented. The low RX insertion loss of the TX leakage canceller is achieved by the autotransformer with loss compensating amplifier. The proposed TX leakage canceller is fabricated in 0.13µm CMOS process. It provides over 55dB rejection of the TX leakage at the RX port and the notch frequency can be controlled from 866MHz to 961MHz using a digitally controlled 4-bit switched capacitor array. The RX insertion loss of the wideband LNA with the TX leakage canceller decreased by 1dB and the NF is decreased about 0.8dB compared to that without the compensating amplifier.

View full abstract

This paper presents a Common-Mode (CM) Built-In Self-Test (BIST) technique for Fully-Differential (FD) Sample-and-Hold (S/H) circuits. Based on the CM test setup, the catastrophic and parametric faults in the MOS switches and hold capacitors can be detected by checking the differential outputs, which should vary around the desired CM output of the FD Operational Amplifier (OpAmp) used in the FD S/H circuits under test. The fault simulation results in circuit-level and the layout design using Rohm 0.18-µm CMOS technology are presented to demonstrate the feasibility of the proposed CM BIST technique for FD S/H circuits.

View full abstract

Successfully imaging of airborne SAR requires that Doppler centroid frequency be accurately estimated. Energy balancing method is a classical method to solve this problem, whereas its performance relies heavily on the homogeneity of the scene. In this paper, the spectra of prominent point targets are analyzed, and then an adaptive algorithm based on Gaussian curve fitting is proposed to eliminate the impact of prominent point targets in the scene. Random estimation error is further eliminated by using linear fitting of estimations from each range cell. The results of simulations and the imaging of raw data prove the veracity of this algorithm.

View full abstract