PORTABLE RADIO COMPRISING A CONNECTABLE CIRCUIT

Abstract: The electronic device comprises an oscillation circuit (1, 2, 3, 10, 11, C1, C2, C3) included in a phase-locked loop which comprises a phase detector (17) and a variable divider (15) depending on a certain quantity. A check circuit is provided which either or not melts a fuse (25) as a function of the magnitude of the output of said phase detector (17) for each quantity of said divider indicating a bad or good locking respectively, of said loop. Application: Determination of wideband radio receiver/transmitter.

Description: Portable radio comprising a connectable circuit. The invention relates to an electronic device comprising an adjustable element which has characteristic features which are to return to a certain pattern. The invention also relates to a radio telephone handset and a system for acting on said adjustable element. Such an invention particularly relates to portable radio devices used in mobile telephones for which the adjustable element is the first local oscillator. In this type of application, the telephone is to receive over a wide frequency range. It happens that, as a result of the spreading of its components, an oscillator is incapable of covering the ranges imposed by the pattern and that corrections are to be made therein. This type of corrections is made by causing a variation in the capacitance of the capacitor or the self-inductance of the coil forming the oscillator resonant circuit. On this subject could be consulted the French Patent document FR 2 612 017. The drawback of all this is that the tuning at the end of the manufacturing process remains a costly operation, because the adjustment of the value of a capacitor or of a self-inductance takes time. The present invention proposes a device of the type defined in the openin paragraph whose adjustment becomes extremely simple. Therefore, such a device is characterized in that said adjustable element comprises a correction element which can be switched by a fuse. It is noted that the fact that a fuse can be melted is a simple operation which can be rapidly executed and rendered automatic for a check circuit operated at the end of the manufacturing process. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. In the drawings: Fig. 1 shows a first electronic device according to the invention, Fig. 2 shows a system for melting a fuse according to the invention. In Fig. 1 is shown an oscillator circuit formed by an inductance coil 1, a first external fixed capacitor 2, and a second fixed capacitor 3 connected in parallel to the first one. An integrated circuit 5 contains the active elements which permit of generating the oscillation whose frequency is determined partly by the value of these components 1 and 2. The frequency of this oscillator may be changed by varying a bias voltage of varicap diodes 10 and 11. This voltage is produced by a phase-locked loop. This loop is formed by a variable frequency divider 15 whose input derives part of the oscillation and whose output produces a wave whose frequency is equal to the frequency of the input signal divided by a number CH_Nb, and a phase detector 17 of which a first input receives the output signal of the divider 15, and of which a second input receives a reference signal produced by a quartz oscillator 20. Before delivering the apparatus to the client, it is suitable to check whether the oscillator is capable of functioning in the whole frequency range for which it is designed. In other terms, it is to be capable of oscillating for any number CH_Nb. If this oscillation does not occur, according to the invention a fuse 25 is provided. If the oscillation does not take place for a channel, this fuse 25 is melted. According to the preferred embodiment, the circuit 5 is a circuit manufactured by Motorola registered MC13110/MC1311. Although this circuit already comprises switchable capacitors Cl, C2, C3 ... in the oscillation circuit, it has been found that these are sometimes insufficient capacitors to ensure the desired frequency coverage. When the invention is implemented with this integrated circuit, it guarantees oscillation for all the desired channels in 99% of the cases. In this preferred embodiment the fuse is a CMS component of size 805, thus a small-sized component. In Fig. 2 is shown a system for melting the fuse. In this Figure the references which are identical to those of the preceding Figure refer to like elements. Two switch needles 50 and 51 may be brought into contact with the ends 55 and 56 of the fuse 25 which is shown as being disposed on a printed circuit 58. The components of the device are positioned on this circuit. Then, by means of a comparing circuit 60, the output voltage of the phase detector 17 is analyzed for each of the numbers CH_Nb. If this voltage corresponds to a median voltage relative to maximum and minimum stop voltages, the fuse is not melted. If one has a voltage equal to a stop value, a current generator 65 is used and its current, passing through the switch needles 50 and 51 and the contacts 55 and 56, melts the fuse 25. The invention can also be applied to radio transmitters which have to oscillate over a wide range.

Claims: 1. An electronic device comprising an adjustable element which has characteristic features which are to return to a certain pattern, characterized in that said adjustable element comprises a correction element which can be switched by a fuse. 2. An electronic device as claimed in Claim 1, characterized in that the adjustable element is an oscillation circuit formed by a self-inductance and at least one capacitor, and in that the correction element is a capacitor. 3. An electronic device as claimed in Claim 2, characterized in that the oscillation circuit is included in a phase-locked loop comprising a phase detector and a variable divider depending on a certain quantity and in that there is provided a check circuit which either or not melts said fuse as a function of the magnitude of the output of said phase detector for each quantity of said divider indicating a bad or good locking respectively, of said loop. 4. A radio telephone handset, characterized in that it comprises a device as claimed in one of the Claims 1 to 3. 5. A system for acting on said element included in a device as claimed in one of the Claims 1 to 3, characterized in that it comprises means for melting a fuse or the fuses of said adjustable element(s).

Inventors: ROUSSELIN SAMUEL, ROUSSELIN, SAMUEL
Applicants: PHILIPS ELECTRONICS NV, ROUSSELIN SAMUEL, PHILIPS ELECTRONICS N.V., ROUSSELIN, SAMUEL
Application year: 1997
Main classification: H03L7
IPC codes: H03B1, H03B5, H03L7