Session: WE2A | Nonlinear circuit analysis and system modeling |
Chair: | J Stevenson Kenney, Georgia Institute of Technology |
Co-Chair: | Jose Carlos Pedro, University of Aveiro |
Abstract: | The session introduces a wealth of innovative techniques for nonlinear circuit design and simulation and system modeling. |
| | WE2A-1 | A New Mixed Time-Frequency Simulation Method for Nonlinear Heterogeneous Multirate RF Circuits |
10:10 AM-10:30 AM | J. S. Oliveira1, J. C. Pedro2, 1Polytechnic Institute of Leiria, Leiria, Portugal, 2University of Aveiro, Aveiro, Portugal |
(1030) | This paper describes a new mixed time-frequency method especially conceived for the efficient simulation of nonlinear multirate RF circuits evidencing some heterogeneity. The proposed method splits the circuit into two subsets, and can be seen as a hybrid scheme combining the popular envelope transient harmonic balance (ETHB) technique with a purely time-marching engine. With this method, the hardest nonlinearities of the circuit are appropriately computed in a strictly time-domain approach, whereas the more moderate ones are processed in the frequency-domain. Simulation tests are performed with an illustrative circuit example, revealing gains in computation speed of more than one order of magnitude over mature ETHB. |
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WE2A-2 | Discrete-Time Representation of Band-pass Frequency-Domain Data for Envelope Transient Simulation |
10:30 AM-10:50 AM | Z. Su, T. Brazil, University College Dublin, Dublin, Ireland |
(1466) | This contribution offers an extension to the Envelope Transient (ET) family of simulation techniques used in high-frequency simulation involving widely varying time-scales. It is shown how individual band-pass segments of the S-parameter functions of an arbitrary linear network embedded within a non-linear circuit may be represented as compact, complex baseband impulse responses in discrete-time. This kind of description may then be easily incorporated within an ET algorithm using complex convolution. The results obtained by this method have been compared with simulations using direct time-marching simulation in a simple application example showing very good mutual agreement. |
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WE2A-3 | A Polar-oriented Volterra Model for Power Amplifier Characterization |
10:50 AM-11:10 AM | T. R. Cunha, E. G. Lima, J. C. Pedro, Instituto de Telecomunicacoes - Universidade de Aveiro, Aveiro, Portugal |
(1227) | This paper addresses power amplifier (PA) behavioral models that are based on the low-pass equivalent Volterra series approach. As the PA is a band-pass system, the model that processes the complex envelope of the input signal is restricted to the generation of only the first zone output components. It is shown here that such restriction has been interpreted in a too conservative way in the conventional Volterra series based models. Alternatively, we propose a new model formulation which incorporates the band-pass restriction in a more suitable way, significantly increasing the flexibility of the Volterra-based PA models in general. |
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WE2A-4 | Design of pulsed waveform oscillators with a short nonlinear transmission line |
11:10 AM-11:30 AM | M. Ponton, F. Ramirez, A. Suarez, University of Cantabria, Santander, Spain |
(1726) | In this paper we present a new methodology for the design of pulsed-waveform oscillators. The design is based on the use of a short section of nonlinear transmission line (NLTL), constituting the load of a transistor-based subnetwork exhibiting negative resistance. The oscillation start-up conditions are imposed at a transistor port different from the one at which the NLTL is connected, to increase the optimization flexibility. The NLTL is ended in a reactive termination which is optimized in order to reduce the duty cycle of the voltage waveform. Compared with previous works, the new methodology enables a smaller duty cycle with less varactor diodes and no need for adaptive gain in the transistor stage. The methodology has been applied to obtain a pulsed-waveform oscillator at 1.2 GHz, achieving a small duty cycle. Good agreement has been obtained in the comparison with the experimental results. |
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WE2A-5 | Stochastic characterization of the phase noise spectrum of coupled-oscillator circuits |
11:30 AM-11:50 AM | A. Suarez, S. Sancho, F. Ramirez, University of Cantabria, Santander, Spain |
(1771) | This paper presents the phase-noise analysis of nearest-neighbor coupled-oscillator circuits for beam steering applications. The analysis includes the effect of flicker noise sources for the first time to our knowledge. It is based on a semi-analytical formulation, which uses a perturbation model of the individual oscillator extracted from a harmonic balance (HB) simulation of the individual oscillator element in free-running conditions. The model can be extracted from a commercial HB using two auxiliary generators at dc and the first harmonic component. The operation range, stability and phase noise of the coupled system are analyzed separately from HB with the extended semi-analytical formulation. A full stochastic characterization of the phase-noise spectrum from the variance of the phase-deviation is presented, which enables an accurate prediction of the near-carrier noise. |
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