Battery powered magnetic pen having oscillator with improved efficiency and low power consumption

摘要

A battery-powered, magnetic-pen oscillator includes a circuit having a first transistor arranged in a common emitter configuration. A feedback loop includes a transformer and the transistor that produce a loop phase shift of zero degrees and a loop gain of one to cause oscillation, and additionally creates the magnetic field emitted by the pen. A second transistor provides current mirror biasing for the first transistor and determines the amount of current flowing through the first transistor.