Showing papers by "Min Chen published in 2005"
17 Jan 2005
TL;DR: In this article, two methods for reconfigurable transmitters using frequency multipliers in conjunction with digital predistortion linearizers are developed for the amplifier-and doubler-mode operation.
Abstract: Two methods for reconfigurable transmitters using frequency multipliers in conjunction with digital predistortion linearizers are developed. One method utilizes a circuit topology that can be switched between a fundamental-mode in-phase combined amplifier, and a push-push frequency doubler using input phasing. Investigation to maximize output harmonics out of regular power amplifiers (PAs) was performed, and the implementation of the device was successful for the amplifier- and doubler-mode operation. To satisfy optimal load-line conditions for the operation in both modes, a bi-tuned output-combining technique is introduced as well. Measurement results indicate that the circuit is able to transmit 28 dBm of output power at 900 MHz in the amplifier mode, and 22 dBm at 1800 MHz in the doubler mode. In combination with predistortion linearization, the reconfigurable transmitter was shown to be capable of amplifying IS-95B code-division multiple-access (CDMA) signals with an adjacent-channel power ratio (ACPR) up to -58dBc/30kHz. The second suggested method utilizes a fundamental-frequency PA followed by a varactor multiplier that can be bypassed with an RF switch. A varactor-diode doubler with a saturated conversion loss of 1.3 dB was built and tested. Using predistortion linearization techniques on both the PA and doubler, an ACPR of -53dBc/30kHz at 885-kHz offset was achieved for a CDMA signal transmitted at 1850 MHz.
26 citations
06 Mar 2005
TL;DR: In this paper, an emergent power supply for Maglev when it cannot run is presented by injecting a high frequency current to the three phase stator windings and adding an extra linear generator winding to magnetic pole.
Abstract: This paper presents a novel method of emergent power supply for Maglev when it cannot run. It is realized by injecting a high frequency current to the three phase stator windings and adding an extra linear generator winding to magnetic pole. Output power model of linear generator is given. Relationship between the linear generator output power and the injection harmonic current is studied. Finally, experimental results are given.
5 citations