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We propose a novel power metal oxide semiconductor field effect transistor (MOSFET) employing a strained‐Si channel structure to improve the current drivability and on‐resistance characteristic of the high‐voltage MOSFET. A 20 nm thick strained‐Si low field channel NMOSFET with a 0.75 µm thick Si0.8Ge0.2 buffer layer improved the drive current by 20% with a 25% reduction in on‐resistance compared with a conventional Si channel high‐voltage NMOSFET, while suppressing the breakdown voltage and subthreshold slope characteristic degradation by 6% and 8%, respectively. Also, the strained‐Si high‐voltage NMOSFET improved the transconductance by 28% and 52% at the linear and saturation regimes.

A 1.5-bit 20-MHz bandwidth continuous-time deltasigma modulator (CT-DSM), which is suitable for envelope pulsewidth modulation (EPWM) transmitters, is presented. To compensate the process-voltage-temperature variation, a resistor calibration method is proposed. The proposed calibration scheme improves a signal-to-quantization-noise-ratio (SQNR) by 18%. The switched capacitor digital-to-analog converter (DAC) and tri-level output DAC are adopted to improve non-ideal effects and implement multi-level encoding, respectively. Over 44 dB SQNR has been achieved for all corner simulation condition with an oversampling ratio of 13.056 and 20-MHz of bandwidth. The power consumption of the modulator is 11.6 mW from the 1.08 V supply. 1.74 % of error vector magnitude can be obtained for a 20 MHz LTE signal with a 9.7 dB peak-to-average power ratio.

This paper describes the fabrication and characterization of a reconfigurable Yagi-Uda antenna based on a silicon reflector with a solid-state plasma. The silicon reflector, composed of serially connected p-i-n diodes, forms a highly dense solid-state plasma by injecting electrons and holes into the intrinsic region. When this plasma silicon reflector is turned on, the front-realized gain of the antenna increases by more than 2 dBi beyond 5.3 GHz. To achieve the large gain increment, the structure of the antenna is carefully designed with the aid of semiconductor device simulation and antenna simulation. By using an aluminum nitride (AlN) substrate with high thermal conductivity, self-heating effects from the high forward current in the p-i-n diode are efficiently suppressed. By comparing the antenna simulation data and the measurement data, we estimated the conductivity of the plasma silicon reflector in the on-state to be between 104 and 105 S/m. With these figures, silicon material with its technology is an attractive tunable material for a reconfigurable antenna, which has attracted substantial interest from many areas, such as internet of things (IoT) applications, wireless network security, cognitive radio, and mobile and satellite communications as well as from multiple-input-multiple-output (MIMO) systems.

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