Amakawa, Shuhei and Sugimoto, Ryotaro and Tokgöz, Korkut Kaan and Lee, Sangyeop and Ito, Hiroyuki and Kishikawa, Ryoko
(2023)
*Signal-flow-graph analysis of weakly nonlinear microwave circuits around a large-signal operating point.*
IEEE Transactions on Microwave Theory and Techniques, 71
(9).
pp. 3722-3733.
ISSN 0018-9480 (Print) 1557-9670 (Online)

Official URL: http://dx.doi.org/10.1109/TMTT.2023.3248152

## Abstract

A signal flow graph (SFG) representation of small-signal responses of nonlinear microwave circuits around a large-signal operating point is developed using the X-parameters. It is shown that, unlike the SFGs for linear circuits, negative-frequency nodes need to be included explicitly. The development elucidates the circuit-operational meaning of the elusive T-type small-signal X-parameters, which represent the interaction between positive-and negative-frequency components. As an example, such an SFG is used to derive a closed-form expression of the output power of an amplifier as a function of the load reflection coefficient. It is then used to plot approximate load-pull power contours. The result is consistent with the expressions of the optimum load reflection coefficient derived by Root et al. (EuMIC 2017) and power contours derived by Pelaez-Perez et al. (TMTT 2013). SFGs provide an alternative systematic means to derive closed-form expressions in terms of X-parameters and gain illuminating insights into the workings of weakly nonlinear circuits.

Item Type: | Article |
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Uncontrolled Keywords: | Frequency mixing; Harmonic analysis; Impedance; Integrated circuit modeling; intermodulation distortion; Microwave amplifiers; Microwave circuits; Nonlinear circuits; polyharmonic distortion model; S-functions; Scattering parameters; uncertainty propagation; X-parameters |

Subjects: | T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK7800-8360 Electronics |

Divisions: | Faculty of Engineering and Natural Sciences > Academic programs > Electronics Faculty of Engineering and Natural Sciences |

Depositing User: | Korkut Kaan Tokgöz |

Date Deposited: | 03 Oct 2023 15:36 |

Last Modified: | 03 Oct 2023 15:37 |

URI: | https://research.sabanciuniv.edu/id/eprint/48292 |