https://calhoun.nps.edu/bitstream/10945/24839/1/singlesidebandtr00elli.pdf

Single sideband transmission by envelope elimination and restoration.

This study proposes an input-voltage-sharing control scheme for use in input-series-output-series (ISOS) systems. An ISOS system consists of a set of closed-loop DC/DC converters. Each converter has a metal-oxide-semiconductor field-effect transistor (MOSFET) connected in parallel on the input side that is controlled by an input-voltage-sharing loop. The MOSFET works in the linear region to adjust the input power equilibrium. The proposed control scheme makes the closed-loop converters function as power devices that can be combined quickly and flexibly according to the specific voltage conversion requirements, which greatly shortens the time required to develop an ISOS system. The design principle of the input-voltage-sharing loop and the time and frequency domain simulation results are also provided in this study. A 600 W prototype composed of two DC/DC converters was built and employed to verify the steady state and dynamic characteristics of the proposed control scheme.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-pel.2017.0519

Input voltage sharing control scheme for input series and output series DC/DC converters using paralleled MOSFETs

The power conditioning unit system is a critical part in a spacecraft and is responsible for converting the solar panel energy into a stable bus voltage. This system requires a high dynamic characteristic solar array simulator (SAS) for testing purposes. Space solar array simulators (SSASs) used for testing space power systems generally use a linear power topology because of its fast dynamic performance and good simulation accuracy. However, commercially available SASs are not sufficiently fast for simulating the actual solar array panel output and, therefore are unreliable for terrestrial testing. In this paper, a highly dynamic SSAS is developed with multipath SiC MOSFET linear voltage-controlled current source paralleling for power regulation. The proposed 510 W SSAS, consisting of 20 linear current paths paralleling the power stage and a high-speed FPGA digital controller, can quickly react to a load step between the nominal and short circuit at 50-kHz stepping frequency. It can also react to a step change from a short circuit to an open circuit perfectly at a 1-kHz stepping frequency offering a superior dynamic performance compared to other similar devices.

High Dynamic Performance Solar Array Simulator Based on a SiC MOSFET Linear Power Stage

In modern mobile communication systems, spectral efficient modulation formats have been widely used, which results in the envelope of the radio frequency (RF) signal is variable and having large peak to average power ratio (PAPR). In order to amplify the RF signal without distortion, the linear power amplifier (LPA) is adopted, which is less efficient when powered by constant voltage. Three popular techniques, i.e., Doherty, envelope elimination and restoration (EER), and envelope tracking (ET) techniques, to greatly improve the efficiency of the power amplifiers are analyzed and compared in this paper, and it is shown that the ET technique is the most suitable for future mobile communication systems. In the ET systems, the ET power supply is the key equipment, which dominates the system efficiency. With the development of the mobile communication systems, the bandwidth and the PAPR of the envelope signals are increasing rapidly, which pose severe challenges on the design of the ET power supply. This paper summarizes and sorts the ET power supplies in the literatures, and a detailed comparison is presented to guide the selection of ET power supplies for different applications. Finally, the methods, including soft-switching, slow envelope, and band separation are proposed for further increasing the efficiency of the ET power supply.

/pdf/a-review-of-envelope-tracking-power-supply-for-mobile-4v65yu3fx5.pdf

A Review of Envelope Tracking Power Supply for Mobile Communication Systems

An envelope-tracking (ET) technique can greatly enhance the efficiency of the power amplifier in wireless communication system. Among the structures of the ET power supply, the switch-linear hybrid (SLH) structure can obtain both high-tracking bandwidth and high efficiency. An implementation of series–parallel-form SLH ET power supply is proposed in this paper, which includes one multilevel converter, one linear amplifier, and two buck converters. The two buck converters adopt current sensor-less prediction control and are operated at critical conduction mode (CRM). In order to ensure the operation of CRM and provide as much load current as possible, a quasi-interleaved current control scheme is proposed for the two buck converters. Moreover, a peak current restriction method is proposed to prevent the output current of the two interleaved buck converters from excessively exceeding the load current, avoiding the increase of the power loss in the linear amplifier. Finally, a prototype is fabricated with the specifications as 5-MHz tracking bandwidth, 9.6–26.4-V output voltage, and 20-W average output power. The overall measured efficiency is 81.0%, and the normalized-mean-square error is 0.28% when tracking the envelope of wideband code division multiple access signal.

Quasi-Interleaved Current Control for Switch-Linear Hybrid Envelope-Tracking Power Supply

Envelope elimination and restoration technique and envelope tracking technique are proposed to enhance efficiency of radio frequency power amplifier (RFPA), and both of them take envelope amplifier (EA) as a high slew-rate variable voltage source. Serial linear-assisted switching converter, one of the solutions of EA, has benefits in high tracking bandwidth, high tracking accuracy, and relatively low switching losses. Among those many types of linear-assisted switching converter, the design of a linear regulator is rarely mentioned. This paper proposes a new design of linear regulator to supply a higher voltage and maintain high tracking bandwidth by dividing a linear regulator into four different parts. Beyond that, an input filter is recommended to increase the power supply rejection ratio (PSRR) of a linear regulator in high frequency, which is able to reduce the glitch caused by multilevel voltage power supply. An EA prototype is composed of the proposed linear regulator, the PSRR improvement filter, and the multilevel voltage power supply. To align signals, circular convolution is suggested as a modified algorithm. Experiments show that this prototype has a maximum output of 40 V, a tracking bandwidth of about 2 MHz for a full-range sinusoidal signal, and a tracking ability for OFDM envelope signal with a subcarrier up to 5 MHz.

Donglai Zhang

Papers

Linear Regulator Design Considerations of the Serial Linear-Assisted Switching Converter Used as Envelope Amplifier