Infineon Technologies Ag

Walter Mevissen

Markus Hammes

Giuseppe Li Puma

André Hanke

Thomas Convent

Bart Balm

The invention specifies a circuit arrangement with a phase locked loop (), which can be used as a mobile radio transmitter, in particular. The reference frequency for the PLL (), which is provided by means of the source (), is multiplied by a multiplier () and is down-converted to an intermediate-frequency level in a down-conversion mixer () using the output signal from the PLL, and is evaluated such that a modulator () connected to the input of the oscillator () can be trimmed. The inventive principle is used to advantage in two-point modulators and allows inexpensive, integratable mobile radio transmitters with good noise characteristics.

Circuit arrangement provided with a phase-locked loop and transmitter-receiver with said circuit arrangement

A phase locked loop has a voltage controlled oscillator with two tuning inputs. One tuning input can be supplied with a feedback signal via a frequency divider in a conventional phase locked loop. A frequency word, which is provided anyway for the purpose of setting the division ratio of the PLL and hence for the purpose of frequency preselection, is used not only to supply the frequency divider but also for compensatory tuning of frequency-determining components in the oscillator. The phase locked loop allows, particularly in inexpensive open loop modulation methods, a significant reduction in the frequency drift by virtue of a smaller or disappearing discrepancy in the tuning voltage in conjunction with a reduction in the memory effect of capacitors in loop filters using particularly simple circuitry measures.

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Düsseldorf, Germany

Walter Mevissen