Patent ID: 6658244
Filing Date: 2003-12-02
Classification: H03D,H03F,H04L

Abstract:
A method for compensation control of offset voltages in baseband in a radio receiving circuit integrated in a circuit module that operates using a time-division multiple access method (TDMA) with reception timeslots, which comprises the steps of:using a sampling operational amplifier for tapping off a baseband output signal, an output of the sampling operation amplifier charging and discharging an externally fitted capacitor in dependence on a polarity of an offset voltage via a sampling switch of a sample and hold circuit; switching on the sampling switch using an offset compensation enable (OCE) control signal before each reception timeslot in order to carry out an offset compensation process; using a differential amplifier for comparing a voltage applied to the capacitor internally with a reference voltage resulting in a compensation current for counteracting the offset voltage; producing the OCE control signal supplied to the sampling switch within the circuit module using a sequencer functioning as a sequence controller provided in the circuit module, the sequencer is always started even before a start of an active TDMA reception timeslot and, for specific signals, emits a state sequence which is defined such that it is fixed in time, for a sequence control of the circuit module, the sequencer contains a running-down counter which, together with decoding logic at an output of the counter, emits the state sequence; and starting the sequencer in dependence on three pulsed control signals which are input to the circuit module via a three-conductor bus and the sequencer starts when one of the three pulsed control signals has an edge, while the other two pulsed control signals are in a high state.