Influence of Phosphorus Content and Magnetic Annealing on Soft Magnetic Properties of Electrodeposited Amorphous FeMnP Alloy Films

In this work, we investigated the influence of phosphorus and magnetic anneal on the soft magnetic properties of electrodeposited FeMnP alloy films prepared by changing sodium hypophosphite concentrations. X-ray diffraction radiation patterns showed an amorphous structure of electrodeposited alloy films. The saturation magnetization and coercivity value decreased from 586 emu/cc to 346 emu/cc, and 52 Oe to 18 Oe, with the P content increased, respectively. The absorption resonance peak became broad as the P content increased, and the natural resonance frequency decreased from 1.8 GHz to 0.6 GHz, with the P content increasing. Magnetic annealing of samples reduced the magnetic damping, and natural resonance frequency increased by about 1.8 GHz and 3.5 GHz for the sample with lower and higher P content. The film structure with lower P content changed at 300˚C, while the structure remains unchanged for the films with higher P content. Thus, the crystallization temperature could depend on the P content in the film. FeMnP alloy films could be used in high-frequency devices.

Natural frequency for exponential shaped thermoacoustic resonator

The two-dimensional nonlinear acoustic field of eleven exponential shaped res- onators was simulated with a computational fluid dynamics software Fluent. The influence of driving frequency and driving intensity on pressure in resonator as well as its natural frequency was investigated. The relationship between natural frequency and theoretical calculation res- onance frequency was also explored. It is found that beating phenomena can be observed in the resonator when the driving frequency deviates from the natural frequency. Moreover, the natural frequency of resonator increases with the increasing of driving intensity, which shows a hard spring effect. However, the driving intensity plays little effect on natural frequency and the natural frequencies are smaller than the theoretical calculation values in any driving intensity. Meanwhile, a formula between the natural frequency and its first-order resonance frequency from theoretical calculation was obtained by linear fitting for all these exponential shaped resonators under consideration. It is also found that the highest pressure amplitude and highest pressure ratio can be obtained from the exponential shaped resonator of m = 2.8 under the same driving intensity. Moreover, the relation between natural frequency and the theoretical resonance frequency for m = 2.8-tube is slightly different from other tubes in consideration.

A fast transient response low dropout regulator with current control methodology

A transient performance optimized CCL-LDO regulator is proposed.In the CCL-LDO,the control method of the charge pump phase-locked loop is adopted.A current control loop has the feedback signal and reference current to be compared,and then a loop filter generates the gate voltage of the power MOSFET by integrating the error current.The CCL-LDO has the optimized damping coefficient and natural resonant frequency, while its output voltage can be sub-l-V and is not restricted by the reference voltage.With a 1μF decoupling capacitor,the experimental results based on a 0.13μm CMOS process show that the output voltage is 1.0 V;when the workload changes from 100μA to 100 mA transiently,the stable dropout is 4.25 mV,the settling time is 8.2μs and the undershoot is 5.11 mV;when the workload changes from 100 mA to 100μA transiently,the stable dropout is 4.25 mV,the settling time is 23.3μs and the overshoot is 6.21 mV.The PSRR value is more than -95 dB.Most of the attributes of the CCL-LDO are improved rapidly with a FOM value of 0.0097.