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This study develops a post-linearization technique to simultaneously improve the input third-order intercept point (IIP3) and image-rejection ratio (IRR) of a 17GHz low noise amplifier (LNA) in a [email protected] standard CMOS process. A third-order intermodulation distortion (IMD3) compensator constructed by a second-order notch filter was proposed to achieve both high linearity and image reject (IR) of the cascode LNA. The correlation between the post-linearization and IR techniques is analyzed and discussed. The measured LNA achieved a gain of 16.5dB, a noise figure (NF) of 4.58dB, an IIP3 of 0dBm, and an IRR from 68 to 78dB. The improvements of IIP3 and IRR are 11.7 and 46dB, respectively, better than that of the LNA without the notch filter. The proposed IR LNA with total current dissipation of 4.8mA under 1.8V supply voltage and notch filter only dissipate a DC power of 2mW.

An active power filter with asymmetric inverter legs are presented to eliminate harmonics, compensate reactive power and draw the balanced line current from the AC source under balanced and unbalanced load conditions. Three inverter legs are used in the adopted voltage source inverter. In each leg, four active switches are adopted to achieve three-level pulse-width modulation (PWM). No clamped diode or flying capacitor is used in the proposed inverter. In the adopted control algorithm, a classical proportional-integral voltage controller and hysteresis current controller are used to maintain DC-link voltage constant and to track line current commands, respectively. A voltage compensator is added in the inner control loop to compensate the neutral point voltage variation due to load variation. Based on the proposed PWM control scheme, a three-level voltage pattern is generated on the AC terminal of the inverter. The system configuration and mathematical analysis are discussed in the paper. Finally, the experimental results based on a laboratory scaled down prototype are provided to verify the effectiveness of the control algorithm.

A three-phase four-wire power factor corrector based on neutral-point-clamped (NPC) topology is adopted to reduce the current harmonics and increase the input power factor. Using the NPC topology, the voltage stress of power switches can be reduced to the half of the dc-link voltage. With the dc-link voltage controller and the phase locked loop circuit, the balanced and sinusoidal line currents can be drawn from the ac supply system under the balance and unbalance mains voltages. The hysteresis current comparators are adopted in the current control loop to track the line current commands. Three voltage levels are generated on the ac terminal to the neutral point. Simulations and experiments are provided to verify the validity and the effectiveness of the proposed control scheme.

A new active power filter with asymmetric inverter legs are presented to suppress harmonics, compensate reactive power and draw the balanced line current from the AC source under balanced and unbalanced load conditions. In the adopted control algorithm, a classical proportional-integral voltage controller and hysteresis current controller are used to maintain DC link voltage constant and to track line current commands. A voltage compensator is added in the control loop to compensate the neutral point voltage variation due to load variation. The system configuration and mathematical analysis are discussed in the paper. Finally, the experimental results based on a laboratory scaled down prototype are provided to verify the effectiveness and validity of the proposed control algorithm.

A novel three-phase two-leg switch-clamped inverter is presented to achieve multilevel PWM operation, harmonics elimination, reactive power compensation and dc-link voltage regulation. Four active switches with voltage stress of dc-link and two ac switches with voltage stress of half dc-link are used in the proposed inverter. In this paper, the proposed inverter is operated as a controllable current source to supply the necessary active power for the compensation of inverter losses, to suppress current harmonics, and to compensate the reactive power drawn from the nonlinear loads. Therefore, the balanced and sinusoidal line currents are drawn from the ac source. Two control loops are used in the adopted control scheme to maintain the constant dc-link voltage and to achieve the line current command tracking. The mathematical model of the proposed converter for the operation active power filter is derived and the control scheme is provided. Computer simulations and experimental results based on a laboratory scale-down prototype are presented to verify the effectiveness of the proposed control scheme.

A novel single-phase unidirectional power flow rectifier is proposed to achieve power factor correction and dc bus voltage regulation. Four active switches, two power diodes and two dc-side capacitors are used in the proposed circuit topology to generate a three-level PWM voltage waveform on the ac terminal of the proposed rectifier. To compare with NPC and capacitor-clamped topologies, no clamping diode or flying capacitor is used in the proposed rectifier. The reference line current is derived from the dc-tank voltage controller and a sine wave generator in phase with mains voltage. The carrier-based current controller is used in the inner loop to track the line current command. A neutral point voltage compensator is adopted in the control scheme such that the capacitor voltages on the dc side are balanced. The effectiveness of the proposed control algorithm is verified by the computer simulations and experimental results.

In this paper, a single-phase switching mode rectifier is presented to improve the power factor, reduce current harmonics and regulate dc bus voltage. Six active switches are used in the proposed rectifier to achieve the three-level pulse-width modulated operation. Two rectifier legs are used in the adopted rectifier. The rectifier leg-a is operated at the carrier frequency and rectifier leg-b is operated at the line frequency. With appropriate control scheme, three voltage levels and two voltage levels are generated on the rectifier leg-a and leg-b, respectively. Two control loops are adopted in the control scheme to achieve line current command tracking and dc-link voltage regulation. A neutral point voltage compensator is adopted in the system to balance the capacitor voltages on the dc side. Based on the proposed control scheme, a three-level pulse- width modulated waveform is generated on the ac terminal of the rectifier. Experiments are provided to verify the performance of the control scheme.

An asymmetrical voltage source inverter is proposed to operate as an active power filter to eliminate harmonics and compensate reactive power drawn from the nonlinear loads such that a sinusoidal line current is drawn from the ac source. Two inverter legs are used in the adopted circuit configuration. One inverter leg is operated in the line frequency and the other leg is operated in the high switching frequency to track the compensated current command. In the proposed control scheme a voltage compensator, a carrier-based current controller and a proportional integral based DC link controller are used to achieve balanced capacitor voltages, to track line current and to obtain a constant DC bus voltage, respectively. Based on the PWM control scheme a three-level voltage pattern is generated on the AC terminal of the inverter. Experimental results are provided to verify the effectiveness of the control scheme.

A single-phase half-bridge switching mode rectifier is presented to draw a sinusoidal line current, to achieve power factor correction and to maintain the dc-link voltage constant. Four active switches with voltage stress of half dc bus voltage are used in the proposed rectifier to generate a unipolar PWM voltage waveform on the ac terminal voltage. There is no clamping diode in the proposed rectifier compared with the neutral point clamped converter to achieve three-level PWM operation. Two control loops are used in the proposed control scheme. In the outer control loop, a proportional integral voltage controller is used to regulate the dc-link voltage. A phase lock loop circuit is adopted to generate a sinusoidal waveform in phase with mains voltage to achieve power factor correction. In the inner control loop, a carrier-based current controller is used to track the line current command. The experimental results are presented to verify the effectiveness of the proposed control algorithm.

An eight-switch three-phase neutral-point switch-clamped rectifier is presented to achieve the high input power factor and draw the sinusoidal currents from the AC mains. In the conventional three-phase neutral-point switch-clamped rectifier, the circuit configuration consists six power switches with voltage stress v/sub dc/ and three ac power switches with voltage stress V/sub dc//2. There are only four power switches with voltage stress of DC bus voltage and two AC power switches with a voltage stress of half the DC bus voltage in the proposed rectifier. The main functions of the proposed control scheme are to achieve unity input power factor, to draw the sinusoidal line currents from the AC source, and to keep the DC link voltage constant. The analysis and mathematical model of the proposed rectifier is derived. Some simulations and experimental results are provided to verify the effectiveness of the proposed control scheme.

This paper introduces a novel AC line conditioner with high input power factor and clean AC output voltages for isolating the linear or nonlinear loads. A four-wire AC/DC rectifier with switch-clamped topology is adopted to draw the balanced sinusoidal line currents from the AC supply system. The hysteresis comparators are used in the inner control loop to track the line current commands with unity power factor. The DC bus voltage controller is adopted in the outer control loop to regulate the DC-link voltage. A voltage compensator is used to reduce the voltage unbalance between the two DC side capacitor voltages. A four-wire three-leg inverter with switch-clamped topology is adopted in the system to provide clean AC output voltages to the critical or sensitive loads. The carrier-based current control scheme is adopted to generate the stable output voltages. There are three voltage levels generated on the phase to neutral voltage of the proposed system. Based on the proposed control scheme, the sinusoidal line currents with nearly unity power factor can be drawn from the AC supply system, and the balanced AC voltages can be provided to the output load. Experimental results show the validity and effectiveness of the proposed control strategy.

A three-phase four-wire voltage source inverter for power quality compensator under the balanced and unbalanced conditions is proposed to provide balanced three-phase source currents and improve input power factor. The proposed inverter is based on the conventional three-phase voltage source inverter with three additional AC power switches to perform three-level pulse width modulation. The voltage stress of three AC power switches is clamped to half DC-link voltage. The balanced reference line currents are estimated using the DC bus voltage and load currents. A voltage controller is used in the outer loop control to compensate the switching losses of the voltage source inverter. To perform the integrated power quality compensation, hysteresis current control scheme is adopted to track the balanced line current commands in phase with mains voltages. Three voltage levels are generated on the AC terminal of the proposed inverter. Simulation results were provided to verify the effectiveness of the proposed control scheme.

A novel single-phase half-bridge rectifier is presented to achieve power factor correction and harmonic current reduction. The circuit topology of the adopted rectifier consists of two power switches and two diodes. The unipolar PWM voltage waveform is generated on the AC terminal of the adopted rectifier. A carrier based current controller is used in the inner loop to achieve the power factor correction and draw a sinusoidal fine current from the mains. To maintain the DC-link voltage constant, a proportional integral voltage controller is adopted in the outer loop. A capacitor voltage compensator is employed in the proposed control algorithm to balance the neutral point voltage. To investigate the effectiveness of the proposed control scheme, experimental results are presented.

A novel single-phase ac/ac converter is proposed to draw a sinusoidal line current with nearly unity power factor and to provide a stable ac voltage to the critical loads. The proposed ac/ac converter is based on the half-bridge neutral-point diode-clamped topology. The rectifier part is controlled to generate a unipolar PWM waveform on the ac terminal using the power switches with voltage stress of half the DC link. The current control scheme with fixed switching frequency is employed in the inner control loop to track the line current command. To regulate the dc bus voltage, a proportional-integral (PI) control is adopted in the outer control loop. The inverter part with half-bridge neutral point clamped scheme is employed to generate a stable and clean sinusoidal output voltage to the critical load. The experimental results based on a laboratory prototype were implemented to verify the effectiveness of the proposed control scheme.

A three-phase multilevel rectifier with reduced number of power switches to achieve high-power factor, low harmonics and high-voltage capability is presented. In the conventional three-phase neutral point clamped rectifier, 12 power switches are used to draw the sinusoidal line currents with unity power factor. The main drawback of these systems is the large number of power switches used in the circuits. Only six power switches with voltage rating of half DC-link are adopted in the proposed multilevel rectifier. Based on the proposed control strategy, the input power factor is close to unity and line currents are controlled to be balanced and sinusoidal. Simulation and experimental results are provided to verify the effectiveness of the proposed control strategy based on a laboratory prototype.

A new AC line conditioner with high input power factor and clean AC output voltages for isolating the linear or nonlinear loads is introduced. An AC/DC rectifier with switch-clamped topology is adopted to draw the balanced sinusoidal line current from the AC supply system. A three-leg inverter with switch-clamped topology is adopted in the system to provide clean AC output voltages to the critical or sensitive loads. Experimental results show the validity and effectiveness of the proposed control strategy.