Programmable oscillator using magnetoresistive memory technology

Abstract

A programmable oscillator including a memory array of magnetoresistive memory elements, where the memory array is programmed to any one of multiple states based on one or more values and provides an output signal that controls a variable oscillator. The variable oscillator provides a frequency signal that corresponds to the output signal. The oscillator may be a voltage controlled oscillator (VCO) where the memory array is a voltage divider receiving a voltage reference signal and having a voltage junction that asserts a control voltage to the VCO. The voltage divider may include multiple voltage dividers, each including resistive circuits coupled on either side of the voltage junction and each programmed by a corresponding value. A frequency select register stores a frequency select value to program a frequency voltage divider. A trim select register stores a trim value to program a trim voltage divider. A frequency control block receives a reference clock and the frequency signal and generates an error value that programs a dither voltage divider. A portion of the memory array may be preprogrammed for calibration. The voltage reference signal may be provided to an analog to digital converter that programs a compensation resistive circuit in the memory array. Alternatively, the memory array is configured as a variable current source that provides an output current signal to a current controlled oscillator. The values are combined into a programmable register, where the collective value of the register programs the variable current source on a periodic basis.