A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless Communications

A reconfigurable CMOS inverter-based stacked power amplifier (PA) is proposed to extend impedance coverage, while maintaining an output power exceeding the specific power level under the worst antenna impedance mismatch conditions. The adopted process technology supports multi-threshold metal-oxide-...

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Main Authors: Dong-Myeong Kim, Dongmin Kim, Hang-Geun Jeong, Donggu Im
Format: Article
Language:English
Published: MDPI AG 2020-03-01
Series:Electronics
Subjects:
Online Access:https://www.mdpi.com/2079-9292/9/4/562
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author Dong-Myeong Kim
Dongmin Kim
Hang-Geun Jeong
Donggu Im
author_facet Dong-Myeong Kim
Dongmin Kim
Hang-Geun Jeong
Donggu Im
author_sort Dong-Myeong Kim
collection DOAJ
description A reconfigurable CMOS inverter-based stacked power amplifier (PA) is proposed to extend impedance coverage, while maintaining an output power exceeding the specific power level under the worst antenna impedance mismatch conditions. The adopted process technology supports multi-threshold metal-oxide-semiconductor field-effect transistor (MOSFET) devices, and therefore, the proposed PA employs high threshold voltage (<i>V<sub>th</sub></i>) MOSFETs to increase the output voltage swing, and the output power under a given load condition. The unit cell of the last PA stage relies on a cascode inverter that is implemented by adding cascode transistors to the traditional inverter amplifier. By stacking two identical cascode inverters, and enabling one or both of them through digital switch control, the proposed PA can control the maximum output voltage swing and change the optimum load <i>R<sub>opt</sub></i>, resulting in maximum output power with peak power added efficiency (<i>PAE</i>). The cascode transistors mitigate breakdown issues when the upper cascode inverter stage is driven by a supply voltage of 2 × <i>V<sub>DD</sub></i>, and decrease the output impedance of the PA by changing its operation mode from the saturation region to the linear region. This variable output impedance characteristic is useful in extending the impedance coverage of the proposed PA. The reconfigurable PA supports three operation modes: cascode inverter configuration (CIC), double-stacked cascode inverter configuration (DSCIC) and double-stacked inverter configuration (DSIC). These show <i>R<sub>opt</sub></i> of around 100, 50 and 25 Ω, respectively. In the simulation results, the proposed PA operating under the three configurations showed a saturated output power (<i>P<sub>sat</sub></i>) of +6.1 dBm and a peak <i>PAE</i> of 41.1% under a 100 Ω load impedance condition, a <i>P<sub>sat</sub></i> of +4.5 dBm and a peak <i>PAE</i> of 44.3% under a 50 Ω load impedance condition, and a <i>P<sub>sat</sub></i> of +5.2 dBm and a peak <i>PAE</i> of 37.1% under a 25 Ω load impedance condition, respectively. Compared to conventional inverter-based PAs, the proposed design significantly extends impedance coverage, while maintaining an output power exceeding the specific power level, without sacrificing power efficiency using only hardware reconfiguration.
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spelling doaj.art-a640770230024fbbbc256709881071e12023-11-16T14:30:37ZengMDPI AGElectronics2079-92922020-03-019456210.3390/electronics9040562A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless CommunicationsDong-Myeong Kim0Dongmin Kim1Hang-Geun Jeong2Donggu Im3Division of Electronic Engineering, Jeonbuk National University, Jollabuk-do 561-756, KoreaDivision of Electronic Engineering, Jeonbuk National University, Jollabuk-do 561-756, KoreaDivision of Electronic Engineering, Jeonbuk National University, Jollabuk-do 561-756, KoreaDivision of Electronic Engineering, Jeonbuk National University, Jollabuk-do 561-756, KoreaA reconfigurable CMOS inverter-based stacked power amplifier (PA) is proposed to extend impedance coverage, while maintaining an output power exceeding the specific power level under the worst antenna impedance mismatch conditions. The adopted process technology supports multi-threshold metal-oxide-semiconductor field-effect transistor (MOSFET) devices, and therefore, the proposed PA employs high threshold voltage (<i>V<sub>th</sub></i>) MOSFETs to increase the output voltage swing, and the output power under a given load condition. The unit cell of the last PA stage relies on a cascode inverter that is implemented by adding cascode transistors to the traditional inverter amplifier. By stacking two identical cascode inverters, and enabling one or both of them through digital switch control, the proposed PA can control the maximum output voltage swing and change the optimum load <i>R<sub>opt</sub></i>, resulting in maximum output power with peak power added efficiency (<i>PAE</i>). The cascode transistors mitigate breakdown issues when the upper cascode inverter stage is driven by a supply voltage of 2 × <i>V<sub>DD</sub></i>, and decrease the output impedance of the PA by changing its operation mode from the saturation region to the linear region. This variable output impedance characteristic is useful in extending the impedance coverage of the proposed PA. The reconfigurable PA supports three operation modes: cascode inverter configuration (CIC), double-stacked cascode inverter configuration (DSCIC) and double-stacked inverter configuration (DSIC). These show <i>R<sub>opt</sub></i> of around 100, 50 and 25 Ω, respectively. In the simulation results, the proposed PA operating under the three configurations showed a saturated output power (<i>P<sub>sat</sub></i>) of +6.1 dBm and a peak <i>PAE</i> of 41.1% under a 100 Ω load impedance condition, a <i>P<sub>sat</sub></i> of +4.5 dBm and a peak <i>PAE</i> of 44.3% under a 50 Ω load impedance condition, and a <i>P<sub>sat</sub></i> of +5.2 dBm and a peak <i>PAE</i> of 37.1% under a 25 Ω load impedance condition, respectively. Compared to conventional inverter-based PAs, the proposed design significantly extends impedance coverage, while maintaining an output power exceeding the specific power level, without sacrificing power efficiency using only hardware reconfiguration.https://www.mdpi.com/2079-9292/9/4/562antenna impedance mismatchbreakdowncascode inverterCMOSimpedance coveragepower added efficiency
spellingShingle Dong-Myeong Kim
Dongmin Kim
Hang-Geun Jeong
Donggu Im
A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless Communications
Electronics
antenna impedance mismatch
breakdown
cascode inverter
CMOS
impedance coverage
power added efficiency
title A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless Communications
title_full A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless Communications
title_fullStr A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless Communications
title_full_unstemmed A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless Communications
title_short A Reconfigurable CMOS Inverter-based Stacked Power Amplifier with Antenna Impedance Mismatch Compensation for Low Power Short-Range Wireless Communications
title_sort reconfigurable cmos inverter based stacked power amplifier with antenna impedance mismatch compensation for low power short range wireless communications
topic antenna impedance mismatch
breakdown
cascode inverter
CMOS
impedance coverage
power added efficiency
url https://www.mdpi.com/2079-9292/9/4/562
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