GB862426A - Improvements in or relating to frequency transformation devices - Google Patents

Abstract

862,426. Semi-conductor frequency divider circuits. PHILIPS ELECTRICAL INDUSTRIES Ltd. March 8, 1957 [March 13, 1956], No. 7750/57. Class 40(6) [Also in Groups XXXV and XXXVI] A frequency divider comprises a plate of a material of the type in which the current flowing therethrough may be varied by means of a magnetic field, mounted in a gap in the core of an inductor, the input signal being applied to a non-linear circuit including the inductor and the output being derived from the plate. In Fig. 1 a Hall effect plate 2 is mounted in a gap of a ferrite core comprising a semi-circular part 1 and a rod portion 1<SP>1</SP>. The core is wound with a coil 3 which is fed from an input signal source 5 via a resistor 15 and a capacitor 4. By arranging that the core is saturated by the signal and by suitably choosing the value of the capacitor 4 and resistor 15 it may be arranged that the flux passing through the Hall plate 2 has a large sub-harmonic component. The plate is connected at two opposite sides to a battery 6 and at two further opposite sides to output terminals 14, where the sub-harmonic voltage appears. In order to ensure that the input signal is not applied to the circuit at a point when the input wave passes through zero, a starting circuit comprising a rectifier 11 and a relay 8 is provided. When this relay operates the signal is connected to the circuit by contact 9 and a contact 9<SP>1</SP> brings a capacitor 10 into the circuit to maintain the relay operated. The input circuit 3, 4 is preferably tuned to a frequency lower than 0.66 of the input frequency and preferably to the sub-harmonic. Fig. 5 shows an alternative arrangement in which the input coil 3, 3<SP>1</SP> is wound so that the difference in the fluxes produced by the two parts of the coil passes through the central limb and the Hall plate 2. By this means a strong even subharmonic component is obtained. An odd subharmonic may be obtained as shown in Fig. 6 by arranging the coil 3, 3<SP>1</SP> so that the sum of the fluxes passes through the central limb and the plate 2. In this instance a biasing flux is applied by a winding 23 which is parallel tuned to the sub-harmonic by a capacitor 24. The circuits may use a voltage generator 5 and a series tuned circuit as shown in Figs. 1 and 6 or a current generator and a parallel tuned circuit, as shown in Fig. 5. In an alternative arrangement (Fig. 3) a plate 16 of a material such as bismuth or indium antimony alloy is used, the resistance of which varies with the magnetic field and this is inserted in the air gap of the core in place of the Hall plate. The plate is connected in a bridge circuit which, in the absence of input signal, is balanced.