Silicon Bipolar Distributed Oscillator Design and Analysis

The design of high frequency silicon bipolar oscillator using common emitter (CE) with distributed output and analysis is carried out. The general condition for oscillation and the resulting analytical expressions for the frequency of oscillators were reviewed. Transmission line design was carried out using Butterworth LC filters in which the normalised values Ln and Cn where used to obtain the actual values of the inductors and capacitors used; this largely determines the performance of distributed oscillators. The values of inductor and capacitors in the phase shift network are used in tuning the oscillator. The simulated results show that the oscillator operates at 26MHz, dissipating 15mW power. The result indicates that distributed amplification methodology is viable at high frequency.Keywords: Silicon, Oscillator, Bipolar, Design, Analysi

Radiological evaluation of building materials used in Malumfashi, Katsina state, using gamma-ray spectroscopy analysis

The activity concentrations of naturally occurring radionuclides (226Ra, 232Th and 40K) in building materials (sand, cement, blocks, granite, and paints) used in the construction of buildings in Malumfashi local Government area of Katsina state, Nigeria were determined by means of a gamma-ray spectrometry system using Sodium Iodide thallium activated (NaI(Tl)) detector in a low background configuration. The average activity concentrations for 226Ra, 232Th and 40K ranged from 17.07±4.98 to 50.72±6.74, 23.03±1.54 to 42.91±2.37 and 84.03±5.44 to 363.45±5.27 Bqkg-1 respectively. Except for block samples, all the samples mean activity concentrations were less than their respective world averages. The estimated absorbed gamma dose rate (D) ranged from 30.75±4.22 to 64.57±4.78 nGyh-1and the outdoor annual effective dose equivalent (AEDE) varied from 0.038±0.004 to 0.06±0.0051 mSvy-1; these values are below the worldwide effective dose of 0.07 mSvy-1. The values of radium equivalent activity (Raeq), the external hazard index (Hex) and the internal hazard index (Hin) for all the samples in the present work were lower than the accepted safety limit value of 370 Bqkg-1.Keywords: Radionuclide, hazard indices, gamma-ray spectrometry, building materials, Malumfash