Patent ID: 6373314
Filing Date: 2002-04-16
Classification: H03J,H03L

Abstract:
A portable telecommunication terminal, comprising:an automatic frequency circuit (AFC) that receives a radio telecommunication signal, determines a phase error, provides a phase error signal to a digital-to-analog (D/A) converter, and writes a correction value to a first frequency division ratio register when a value of the D/A converter is changed; a signal temperature compensated crystal oscillator (TXCO) that receives a signal corresponding to the phase error signal of the D/A converter and provides an output frequency to a first frequency divider having a first frequency division ratio, Da, determined by the first frequency division ratio register, the first frequency divider providing an output signal, fr; and a voltage controlled oscillator (VCO) having an output frequency, fo, that provides a sub-system clock, which is substantially invariant to the phase error, and substantially equals the output frequency of the TXCO multiplied by a ratio of the first frequency division ratio, Da, of the first frequency divider and a second frequency division ratio, Db, of a second frequency divider such that, f0=fr (Da/Db).