Feedback Networks: Theory and Circuit Applications

Choma, J.; Chen, W K

doi:10.1142/3200

Cited by 39 publications

(22 citation statements)

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“…In fact, the measurement of Z-parameters approaches zero in microwave circuits where the frequencies are very high (over 1 GHz), making the use of reflection coefficients and scattering parameters justifiable for the stability analysis. This explains the abundance of scattering parameters based stability conditions in the microwave systems literature (see, for example, [12]). Conversely, in robotic systems, the measurement of Sparameters is close to zero in any frequency range of practical interest and, therefore, it is highly desirable to have stability conditions that directly depend on the Z-parameters or other immittance parameters of the three-port network.…”

Section: Introductionmentioning

confidence: 91%

Absolute Stability of a Class of Trilateral Haptic Systems

Tavakoli

Huang

2014

IEEE Trans. Haptics

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Abstract-Trilateral haptic systems can be modeled as three-port networks. We present a criterion for absolute stability of a general class of three-port networks. Traditionally, existing (i.e., Llewellyn's) criteria have facilitated the stability analysis of bilateral haptic systems modeled as two-port networks. If the same criteria were to be used for stability analysis of a three-port network, its third port termination would need to be assumed known for it to reduce to a two-port network. This is restrictive because, for absolute stability, all three terminations of the three-port network must be allowed to be arbitrary (while passive). Extending Llewellyn's criterion, we present closed-form necessary and sufficient conditions for absolute stability of a general class of three-port networks. We first find a symmetrization condition under which a general asymmetric impedance (or admittance) matrix Z 3×3 has a symmetric equivalent Zeq from a network stability perspective. Then, via the equivalence of passivity and absolute stability for reciprocal networks, an absolute stability condition for the original nonreciprocal network is derived. To demonstrate the convenience and utility of using this criterion for both analysis and design, it is applied to the problem of designing stabilizing controllers for dual-user haptic teleoperation systems, with simulations and experiments validating the criterion.Index Terms-Three-port network, trilateral haptic system, absolute stability.

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Section: Introductionmentioning

confidence: 91%

Absolute Stability of a Class of Trilateral Haptic Systems

Tavakoli

Huang

2014

IEEE Trans. Haptics

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“…This technique, known as neutralization, was originally proposed to cancel the unwanted internal feedback in a transistor and unilateralize the amplifier [12,13]. The positive reactance can be realized most easily in a differential amplifier with a cross-coupled capacitor pair because the cross-coupled capacitance is, in differential mode, equivalent to negative capacitance [14]. It is known that by adopting cross-coupled feedback capacitance larger than the gate-drain capacitance, the gain can become higher than the unilateral gain.…”

Section: Gain Boosting In Amplifiersmentioning

confidence: 99%

Recent progress and prospects of terahertz CMOS

Fujishima

Amakawa

2015

IEICE Electron. Express

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Recent progress and prospects of terahertz CMOS integrated circuits is reviewed. The development of terahertz CMOS is somewhat different from the conventional digital and RF CMOS evolution, in that it is not fueled as much by technology scaling. Rather, the key enablers are progress in high-frequency device characterization and modeling techniques and also in design techniques near transistor's active operation limit, f max .

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“…Llewellyn's absolute stability criterion gives closed-form conditions on the immittance parameters (impedance, admittance, hybrid [4]) of the two-port network for it to Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Revisiting Llewellyn's absolute stability criterion for bilateral teleoperation systems under non-passive operator or environment

Jazayeri

Tavakoli

2012

2012 IEEE/RSJ International Conference on Intelligent Robots and Systems

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Abstract-Stability of a haptic teleoperation system is influenced by the typically uncertain, time-varying and/or unknown dynamics of the operator and the environment. For a stability analysis that is independent of the operator and the environment dynamics, Llewellyn's absolute stability criterion proposes certain conditions on the two-port network representing the teleoperator (comprising the master, the controller and communication channel, and the slave) assuming that the terminations (i.e., the operator and the environment) are passive. These are less-than-accurate assumptions. It is desirable to extend Llewellyn's result to the cases where the operator or the environment is non-passive. This paper revisits Llewellyn's criterion and relaxes the assumption of passivity for one of the terminations. The possibly non-passive termination is realistically assumed to have a complex impedance with an upper or lower bound on its amplitude or real part, respectively. Although the proposed stability criteria are useful for any application of two-port network systems, we specifically apply them on bilateral teleoperation systems and find the stability conditions when the operator or the environment is not passive; this is a result that Llewellyn's absolute stability criterion cannot afford.

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Feedback Networks: Theory and Circuit Applications

Cited by 39 publications

References 0 publications

Absolute Stability of a Class of Trilateral Haptic Systems

Absolute Stability of a Class of Trilateral Haptic Systems

Recent progress and prospects of terahertz CMOS

Revisiting Llewellyn's absolute stability criterion for bilateral teleoperation systems under non-passive operator or environment

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