Resonate and Fire Neuron with Fixed Magnetic Skyrmions

In the brain, the membrane potential of many neurons oscillates in a subthreshold damped fashion and fire when excited by an input frequency that nearly equals their eigen frequency. In this work, we investigate theoretically the artificial implementation of such "resonate-and-fire" neurons by utilizing the magnetization dynamics of a fixed magnetic skyrmion in the free layer of a magnetic tunnel junction (MTJ). To realize firing of this nanomagnetic implementation of an artificial neuron, we propose to employ voltage control of magnetic anisotropy or voltage generated strain as an input (spike or sinusoidal) signal, which modulates the perpendicular magnetic anisotropy (PMA). This results in continual expansion and shrinking (i.e. breathing) of a skyrmion core that mimics the subthreshold oscillation. Any subsequent input pulse having an interval close to the breathing period or a sinusoidal input close to the eigen frequency drives the magnetization dynamics of the fixed skyrmion in a resonant manner. The time varying electrical resistance of the MTJ layer due to this resonant oscillation of the skyrmion core is used to drive a Complementary Metal Oxide Semiconductor (CMOS) buffer circuit, which produces spike outputs. By rigorous micromagnetic simulation, we investigate the interspike timing dependence and response to different excitatory and inhibitory incoming input pulses. Finally, we show that such resonate and fire neurons have potential application in coupled nanomagnetic oscillator based associative memory arrays

Design Of 0.18-μm CMOS Mixer For Medradio Application

This thesis introduces a component of the Radio Frequency transceiver called the mixer. The mixer is a critical component in the RF systems, as a result of its ability for frequency conversion. This passages focuses on the design analysis and simulation of active down-conversion mixer. This mixer is described by its important design properties which consist of conversion gain, linearity, noise figure, and port isolation. The topologies that are given in this passage range from the most commonly known mixer design, to implement the design methods that are utilized to build the mixer important design properties as the request of CMOS technology and the overall RF system rises. All mixer topologies were designed and simulated using TSMC 0.18 μm CMOS technology in Advanced Design Systems, a test system utilized particularly for RF designs. The design was able to produce the conversion gain about 12.86 dB and 12.85 dB at 401 MHz – 406 MHz respectively. The NFobtained in this topology was 11.2 dB at 401.7 MHz and started to go below 11.19 dB at 405.8 MHz. IP1db and IIP3 was also able to meet the design target specification. Finally, the power consumption is 6.17 Mw at a 1.8 V

Design of compact frequency synthesizer for self-calibration in RF circuits

A compact frequency synthesizer based on a phase locked loop (PLL) is designed for the self-calibration in RF circuits. The main advantage of the presented frequency synthesizer is that it can be built in a small silicon area using MOSFET interface trap charge pump (ITCP) current generators. The ITCP current generator makes it possible to use small currents at nano-ampere levels so that small capacitances can be used in the loop filter. A large resistance, which is required to compensate for the reduced capacitances, is implemented using an operational transconductance amplifier (OTA). An ITCP current generator is used as a tail current source for the OTA in order to realize a small transconductance. The presented frequency synthesizer has the output frequency range from 570 MHz to 600 MHz with a 100 KHz frequency step. Total silicon area is about 0.3 mm2 using AMIS 0.5 ??m CMOS technology, and the power consumption is 26.7 mW with 3 V single power supply