Tuning circuit for adjusting signal frequency of e.g. quartz oscillator, in transmitting or receiving device, has sigma delta modulator coupled with control input at input side and coupled with control port of arrangement at output side

摘要

The circuit has a partial port designed for coupling with a signal input of a unit e.g. quartz crystal, with a resonant frequency. A capacity controllable arrangement (Cv) tunes the resonant frequency of the unit. The arrangement has a control port (52) and a set of charge storage units that are switchable at the control port over a tuning word. A control input (51) supplies a digital control word (DW) of a word width. A sigma delta modulator (5) is coupled with the control input at input side, and is coupled with the control port of the arrangement at output side. An independent claim is also included for a method for frequency controlling of a unit e.g. quartz crystal, quartz oscillator, bandpass filter and surface wave filter.