Analysis of Switched Capacitor Losses in Polar and Quadrature Switched Capacitor PAs

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    Abstract

    This paper derives the efficiency limitations of scpa due to sc losses during charging and discharging of their capacitor arrays. Polar modulation is covered, as well as quadrature modulation both with clock duty cycles of 50% ( q50q50) and 25% ( q25q25). Closed form expressions are derived for both the maximum output power and sc power loss for signals with arbitrary phase and amplitude. These expressions are verified by simulations using ideal switches and capacitors, and 22 nm CMOS transistor models. These results are used to analyze the scpa efficiency for 64QAM signals using a statistical model. It is shown that for a given array capacitance and supply voltage, the polar architecture is the most power efficient. Compared to polar modulation, the sc loss for 64QAM is fundamentally 18% higher for q50 and 46% higher for q25 scpa, whereas the generated output powers are fundamentally 6 and 3dB lower, respectively.
    Original languageEnglish
    JournalIEEE transactions on circuits and systems II: express briefs
    Early online date4 Dec 2019
    DOIs
    Publication statusE-pub ahead of print/First online - 4 Dec 2019

    Fingerprint

    Capacitors
    Modulation
    Clocks
    Transistors
    Capacitance
    Switches
    Electric potential
    Statistical Models

    Keywords

    • Class-D glspa
    • glspa
    • glsrfdac
    • digital glspa
    • polar transmitter
    • quadrature transmitter
    • power generation
    • Switches
    • Capacitance
    • Modulation
    • Mathematical model
    • Capacitors

    Cite this

    @article{68cf959e09774da5bf9d2a32fb59c346,
    title = "Analysis of Switched Capacitor Losses in Polar and Quadrature Switched Capacitor PAs",
    abstract = "This paper derives the efficiency limitations of scpa due to sc losses during charging and discharging of their capacitor arrays. Polar modulation is covered, as well as quadrature modulation both with clock duty cycles of 50{\%} ( q50q50) and 25{\%} ( q25q25). Closed form expressions are derived for both the maximum output power and sc power loss for signals with arbitrary phase and amplitude. These expressions are verified by simulations using ideal switches and capacitors, and 22 nm CMOS transistor models. These results are used to analyze the scpa efficiency for 64QAM signals using a statistical model. It is shown that for a given array capacitance and supply voltage, the polar architecture is the most power efficient. Compared to polar modulation, the sc loss for 64QAM is fundamentally 18{\%} higher for q50 and 46{\%} higher for q25 scpa, whereas the generated output powers are fundamentally 6 and 3dB lower, respectively.",
    keywords = "Class-D glspa, glspa, glsrfdac, digital glspa, polar transmitter, quadrature transmitter, power generation, Switches, Capacitance, Modulation, Mathematical model, Capacitors",
    author = "Zanen, {Joep Osger Pepijn} and Klumperink, {Eric A.M.} and Bram Nauta",
    year = "2019",
    month = "12",
    day = "4",
    doi = "10.1109/TCSII.2019.2957576",
    language = "English",
    journal = "IEEE transactions on circuits and systems II: express briefs",
    issn = "1549-7747",
    publisher = "IEEE",

    }

    TY - JOUR

    T1 - Analysis of Switched Capacitor Losses in Polar and Quadrature Switched Capacitor PAs

    AU - Zanen, Joep Osger Pepijn

    AU - Klumperink, Eric A.M.

    AU - Nauta, Bram

    PY - 2019/12/4

    Y1 - 2019/12/4

    N2 - This paper derives the efficiency limitations of scpa due to sc losses during charging and discharging of their capacitor arrays. Polar modulation is covered, as well as quadrature modulation both with clock duty cycles of 50% ( q50q50) and 25% ( q25q25). Closed form expressions are derived for both the maximum output power and sc power loss for signals with arbitrary phase and amplitude. These expressions are verified by simulations using ideal switches and capacitors, and 22 nm CMOS transistor models. These results are used to analyze the scpa efficiency for 64QAM signals using a statistical model. It is shown that for a given array capacitance and supply voltage, the polar architecture is the most power efficient. Compared to polar modulation, the sc loss for 64QAM is fundamentally 18% higher for q50 and 46% higher for q25 scpa, whereas the generated output powers are fundamentally 6 and 3dB lower, respectively.

    AB - This paper derives the efficiency limitations of scpa due to sc losses during charging and discharging of their capacitor arrays. Polar modulation is covered, as well as quadrature modulation both with clock duty cycles of 50% ( q50q50) and 25% ( q25q25). Closed form expressions are derived for both the maximum output power and sc power loss for signals with arbitrary phase and amplitude. These expressions are verified by simulations using ideal switches and capacitors, and 22 nm CMOS transistor models. These results are used to analyze the scpa efficiency for 64QAM signals using a statistical model. It is shown that for a given array capacitance and supply voltage, the polar architecture is the most power efficient. Compared to polar modulation, the sc loss for 64QAM is fundamentally 18% higher for q50 and 46% higher for q25 scpa, whereas the generated output powers are fundamentally 6 and 3dB lower, respectively.

    KW - Class-D glspa

    KW - glspa

    KW - glsrfdac

    KW - digital glspa

    KW - polar transmitter

    KW - quadrature transmitter

    KW - power generation

    KW - Switches

    KW - Capacitance

    KW - Modulation

    KW - Mathematical model

    KW - Capacitors

    U2 - 10.1109/TCSII.2019.2957576

    DO - 10.1109/TCSII.2019.2957576

    M3 - Article

    JO - IEEE transactions on circuits and systems II: express briefs

    JF - IEEE transactions on circuits and systems II: express briefs

    SN - 1549-7747

    ER -