Pulse or digital communications – Synchronizers – Phase displacement – slip or jitter correction
Reexamination Certificate
2000-11-13
2004-11-23
Tran, Khai (Department: 2637)
Pulse or digital communications
Synchronizers
Phase displacement, slip or jitter correction
C327S145000, C327S147000
Reexamination Certificate
active
06823032
ABSTRACT:
The invention relates to a telecommunication device including a clock generation unit, more particularly for a mobile radio system, having an input for a reference clock, including an electrical circuit arrangement which has a phase-locked loop for converting the reference clock into a working clock. The invention also relates to a clock generation unit as such. Clock generation units are usually inserted in communication devices for mobile radio systems, for example in mobiles, to provide a number of working clocks based on a reference clock which the clock generation unit is supplied with. The different functional units of the mobile are driven via the working clocks. Then, in dependence on the state of operation, the different functional units are supplied with different working clocks. In order to save energy, the function units are supplied with low-frequency working clocks, for example, in the stand-by mode and, on the other hand, with a high-frequency working clock in the radio mode.
The essential component of the clock generation unit (CGU) is the so-called phase-locked loop (PLL), which provides a plurality of working clocks based on the reference clock. The individual frequencies of the working clocks then have a fixed divider ratio to the frequency of the reference clock. The operation of a programmable phase-locked loop is described, for example, in U.S. Pat. No. 5,349,544. The use of a phase-locked loop for generating working clocks in a mobile radio system is known, for example, from WO 97/21278.
For generating as uniform clock signals as possible with steepest possible rising and falling edges, the clock generation unit and the phase-locked loop are tuned to the reference clock. The reference clock is supplied by an external clock generator having a fixed reference clock frequency. The phase-locked loops known from U.S. Pat. No. 5,349,544 and WO 97/21278 are supplied with a fixed reference clock.
In mobile radio systems there are different standards which are based on different reference clocks. Essential standard mobile radio systems are, for example, the GSM system (Global System for Mobile communications), the TDMA system (Time-Division Multiple Access) and the CDMA system (Code-Division Multiple Access). These systems have in common that they are arranged as multiplex systems, more particularly as time-multiplex systems, in which a plurality of time windows are provided within a time frame determined for the respective system, while different data can be transmitted in these time windows. The time frame comprises a plurality of basic units and the basic unit clock is derived from the reference clock of the mobile radio system. The basic unit clocks of the various systems are different from each other. For the GSM system is used a reference clock of 13 Mhz, for the TDMA system a reference clock of 19.44 MHz and for the CDMA system a reference clock of 19.66 MHz.
Due to the different reference clocks, the clock generation unit is to be specifically arranged for each mobile radio system. Since the clock generation unit is generally integrated on a microchip or IC, a change-over from one system to the other is only possible via an expensive change of the layout of the chip and is thus very costly.
The present invention has for its object to provide a telecommunication device including a clock generation unit and a method of generating a working clock, which device and method can be incorporated in the various mobile radio systems.
For achieving the object as regards the clock generation unit, this clock generation unit according to the invention has an input for a reference clock, and includes an electrical circuit arrangement with a phase-locked loop for changing the reference clock into a working clock, which circuit arrangement has circuit portions provided for different reference clocks and one of the circuit portions which is assigned to a special reference clockcan be selected.
The invention thus provides to arrange the telecommunication device or clock generation unit respectively, for use in various mobile radio systems. This is achieved in that mutually alternative circuit portions are installed in the clock generation unit, which portions are arranged for the respective mobile radio system. Depending on which mobile radio system the clock generation unit is to be used for, the circuit portion assigned to this respective mobile radio system is selected. Thus a certain or various defined working clocks are selected via the respective circuit portion.
The invention is based on the consideration that it is considerably more favorable for reasons of cost to install different circuit portions inside the clock generation unit of which only one circuit portion is necessary for use in a communication device (mobile), than keeping a clock generation unit of its own for each mobile radio system. The clock generation unit including the different circuit portions is especially advantageous in that with variations of capacity or variations of demand in the individual mobile radio systems, microchips with the integrated clock generation unit can be inserted into the other mobile radio systems without much expenditure.
In a preferred embodiment the circuit portions include each a divider module integrated particularly in the phase-locked loop, with the aid of which divider module the reference clock assigned to the respective circuit portion is changed into a plurality of working clocks, while the divider module is arranged so that at least several of its working clocks that can be generated by it are substantially the same.
In this respect it is assumed that the individual components in a mobile are tuned to certain working clocks and that it is therefore very efficient to provide those working clocks for which the components are arranged, irrespective of the mobile radio system in which the mobile is to be used. This has the decisive advantage that only the clock generation unit is to be adapted to the mobile radio system and the remaining components can, in essence, further be used unchanged.
When the reference clock is selected, the divider module assigned to the reference clock is selected at the same time as part of the circuit portion specially arranged for the reference clock. The divider modules are different, in essence, as regards the adjusted divider ratios. By arranging a plurality of divider modules, it is possible that at least several of the outputs of the clock generation unit are constantly supplied with the same working clocks, irrespective of the selected reference clock.
In an alternative embodiment there is preferably provided that the phase-locked loop has fixed divider ratios irrespective of the reference clock and that the suitable working clocks are selected via a selecting element. Such a selection normally occurs by sets of register bits and connected gate logic. The circuit portions can preferably be configured, more particularly, programmed, so that the desired working clocks are generated. For this. purpose, the circuit portion is supplied with, for example, respective configuration information. Particularly a fractional divider is provided here, via which substantially any working clock can be generated from any reference clock with a fractional division ratio. Such a fractional divider is particularly used for fine-tuning the working clocks.
Advantageously, the phase-locked loop includes on the input side different sets of circuit components tuned to the reference clocks, which components can be activated alternatively while they determine particularly the locking behavior of the phase-locked loop. This is advantageous in that the phase-locked loop locks on very fast and without any disturbance when switched on, so that it already works reliably after a very brief period of time.
As an alternative, the phase-locked loop includes a special set of switching components, which is suitable for processing a plurality of reference clocks. At the frequencies 19.44 and 19.66 MHz this is preferably achieved in that the set of switching componen
Bening Andreas
Kempf Peter
Walters Eckhard
Lugo David B.
Waxler Aaron
LandOfFree
Telecommunication device including a clock generation unit does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Telecommunication device including a clock generation unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Telecommunication device including a clock generation unit will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3356024