Chaotic Colpitts circuits with fundamental frequency f* beyond 1GHz are studied by both circuit simulation and experiment using Philips' broadband transistor with threshold frequency of 25GHz. For the basic config...Chaotic Colpitts circuits with fundamental frequency f* beyond 1GHz are studied by both circuit simulation and experiment using Philips' broadband transistor with threshold frequency of 25GHz. For the basic configuration of Colpitts circuit with f* of about 1.6GHz, broadband continuous power spectra could be obtained from both circuit simulations and experiments. The harmonics of the observed signal from Agilent PSA/ESA spectrum analyzer are as noticeable as far as 12GHz. A modified Colpitts circuit structure employing the parasitic inductance of BJT (Bipolar Junction Transistor) is also proposed and investigated. By circuit simulation, chaotic attractor and broadband continuous power spectra could be obtained from the modified Colpitts circuit with f* of about 3.5GHz. Because the parasitic effects of the prototype board, the experiment result of the modified Colpitts circuit does not agree well with the simulation result. The gap between the simulation and experimental result could be bridged by replacing the lumped circuit elements with distributed ones.展开更多
We analyze ππ-KK and πη-Kk couple channel [1,1] matrix Padé amplitudes of SU(3) × SU(3) chiral perturbation theory.By fitting phase shift and inelasticity data,we determine pole positions in different ch...We analyze ππ-KK and πη-Kk couple channel [1,1] matrix Padé amplitudes of SU(3) × SU(3) chiral perturbation theory.By fitting phase shift and inelasticity data,we determine pole positions in different channels (f 0 (980),a 0 (980),f 0 (600),K*0 (800),K*(892),ρ(770)) and trace their N c trajectories.We stress that a couple channel Breit-Wigner resonance should exhibit two poles on different Riemann sheets and meet each other on the real axis when N c=∞.Poles are hence classified using this criteria and we conclude that K*(892) and ρ(770) are unambiguous Breit-Wigner resonances.For scalars the situation is much less clear.We find that f 0 (980) is a molecular state rather than a Breit-Wigner resonance,while a 0 (980),though behave oddly when varying N c,do maintain a twin pole structure.展开更多
基金Supported by the National Natural Science Foundation of China (No.60201001).
文摘Chaotic Colpitts circuits with fundamental frequency f* beyond 1GHz are studied by both circuit simulation and experiment using Philips' broadband transistor with threshold frequency of 25GHz. For the basic configuration of Colpitts circuit with f* of about 1.6GHz, broadband continuous power spectra could be obtained from both circuit simulations and experiments. The harmonics of the observed signal from Agilent PSA/ESA spectrum analyzer are as noticeable as far as 12GHz. A modified Colpitts circuit structure employing the parasitic inductance of BJT (Bipolar Junction Transistor) is also proposed and investigated. By circuit simulation, chaotic attractor and broadband continuous power spectra could be obtained from the modified Colpitts circuit with f* of about 3.5GHz. Because the parasitic effects of the prototype board, the experiment result of the modified Colpitts circuit does not agree well with the simulation result. The gap between the simulation and experimental result could be bridged by replacing the lumped circuit elements with distributed ones.
基金Supported by National Natural Science Foundation of China under Grant Nos.10925522,10875001,and 11021092
文摘We analyze ππ-KK and πη-Kk couple channel [1,1] matrix Padé amplitudes of SU(3) × SU(3) chiral perturbation theory.By fitting phase shift and inelasticity data,we determine pole positions in different channels (f 0 (980),a 0 (980),f 0 (600),K*0 (800),K*(892),ρ(770)) and trace their N c trajectories.We stress that a couple channel Breit-Wigner resonance should exhibit two poles on different Riemann sheets and meet each other on the real axis when N c=∞.Poles are hence classified using this criteria and we conclude that K*(892) and ρ(770) are unambiguous Breit-Wigner resonances.For scalars the situation is much less clear.We find that f 0 (980) is a molecular state rather than a Breit-Wigner resonance,while a 0 (980),though behave oddly when varying N c,do maintain a twin pole structure.
