Search

A memcapacitor is a new type of memory capacitor. Before the advent of practical memcapacitor, the prospective studies on its models and potential applications are of importance. For this purpose, we establish a mathematical memcapacitor model and a corresponding circuit model. As a potential application, based on the model, a memcapacitor oscillator is designed, with its basic dynamic characteristics analyzed theoretically and experimentally. Some circuit variables such as charge, flux, and integral of charge, which are difficult to measure, are observed and measured via simulations and experiments. Analysis results show that besides the typical period-doubling bifurcations and period-3 windows, sustained chaos with constant Lyapunov exponents occurs. Moreover, this oscillator also exhibits abrupt chaos and some novel bifurcations. In addition, based on the digital signal processing (DSP) technology, a scheme of digitally realizing this memcapacitor oscillator is provided. Then the statistical properties of the chaotic sequences generated from the oscillator are tested by using the test suit of the National Institute of Standards and Technology (NIST). The tested randomness definitely reaches the standards of NIST, and is better than that of the well-known Lorenz system.

A 3.125 GHz Clock Recovery (CR) circuit used in the 6.25Gbps SerDes for Backplane Communication Receiver is described. Bang-bang PLL architecture is utilized for its high operation speed. An Alexander phase detector (PD) and a LC voltage-control oscillator (VCO) are involved in the circuit. The behavior of the nonlinear bang-bang PLL is modeled to give approximate evaluation of the loop stability. The circuit has been implemented in a standard 0.18 μm CMOS technology. The test result indicates that the frequency of the VCO is from 3 GHz to 3.35 GHz, the voltage gain is 270 MHz/V, and the phase noise is −118.38 dBc/Hz @1 MHz. The chip consumes less than 81 mW with 1.8 V power supply, and occupies 0.5 mm2 area.

Objective To explore the feasibility and clinical effects by transcatheter interventions used for the patient suffering acute myocardial infarction (AMI) complicating with ventricular septal rupture (VSR) postinfarction. Methods Between June 2005 and August 2009, Ventricular septal rupture (VSR) patients diagnosed with VSR underwent transcatheter closure aged 59–79 years old (mean 63.3±24.7). The occluders were released with the monitoring of transthoracic echocardiography (TTE) and X-ray fluoroscopy. Results 3 cases were successfully treated with transcatheter closure. The defect diameter was 11–28 (17±9.5) mm measured by TTE and the size of the occluder was 16–32 (21.3±7.6) mm. The occluder successful rate was 100%. The case success in 2 and a big VSR lead to die in 1. Conclusions VSR was showed by praecordial area auscultation, transthoracic echocardiography (TTE) and left ventricular angiography after AMI. The transcatheter closure of VSR postinfarction is alternative method in patients not suite for surgical closure. But the careful examination and preparation are need before transcatheter closure.