Patent GB-700244-A (GB)
Title: Improvements in semiconductive electrical translating devices
IPC: H03F3/04
Filed: 1950-10-10
Abstract: 700,244. Semi-conductor amplifiers. WESTERN ELECTRIC CO., Inc. Oct. 10, 1950 [Oct. 11, 1949; Oct. 11, 1949] No.24715/50 Class 40 (4) [Also in Groups XXXVI and XL(c)] An electrical translating device comprises a semi-conductor body having two zones of opposite conductivity meeting at a junction, a pair of rectifying contacts engaging the body near to and on opposite sides of the junction and means for biasing, each of the contacts in the reverse direction. In Fig. 1 a base electrode 22 is provided to a semi-conductor body comprising portions 20A, 20B of P and N-type material, and rectifying contacts 1 and 2 are biased in the reverse direction by batteries 24 and 26. It is shown that holes supplied from electrode 1 are attracted to electrode 2, and that electrons supplied by electrode 2 are attracted to electrode 1 so that effectively each acts as an "emitter" for the other. Current multiplication arises due to the space charge 'effects which result from the ensuing distribution of current carriers. The process is repetitive and may provide a stable circuit or may be used to produce oscillations the frequency of which may be determined by impedances 23 and 25 Fig. 3 shows an oscillator circuit comprising tuned circuit elements 27, 28 and in this case the base electrode 22 is modified to extend over both P and N portions of the semi-conductor. Resistance 23 may be used to control the output voltage. Modifications are described in which the P zone is in the form of an island or channel in a body of N-type material. In other arrangements the base electrode is omitted or comprises two separate electrodes applied to the ends of the P and N portions of the body. The rectifying contacts may also be on opposite sides of a thin wafer of P and N semi-conductor material. In Fig. 9 a signal source 31 is applied between electrodes 22B, 22A to modulate currents flowing through electrodes 1 and 2. Battery 30 connected in series with source 31 is arranged to encourage hole flow from the P type region to the N-type region and electron flow in the reverse direction. In further modifications, an emitter biased in the forward direction is associated with one of the existing electrodes 1 or 2 on the same type of material to form a normal transistor having an input signal applied between emitter and base electrodes. The transistor portion and the arrangement comprising electrodes 1 and 2 then effectively provide a cascade amplifier having power and current gain. Push-pull output signals may be taken from electrodes and 2. The device is also photo-sensitive and photo-amplification or modulation of the output may be effected by applying light to the PN junction, since this results in the production of electronhole pairs proportional to the light intensity. Fig. 17 shows a further embodiment in which an emitter E biased in the forward direction is associated with electrode 1 to provide a normal transistor arrangement, and further electrodes 2, 3 and 4 are provided which successively engage portions of opposite conductivity type and are biased in the reverse direction to successively increasing values. Current-gain is obtained between each pair of contacts, and the device may provide push-pull amplification at output circuit 133. In a further arrangement the P and N-types of material may be arranged in chessboard fashion each square containing one electrode, and the path taken by the signal may be controlled by varying the bias applied to the electrodes. Fig. 22 shows such an arrangement for use as a multiplex switch. The input is applied to emitter electrode E and the bias of electrodes 1-10 is controlled by switches 134; 135. By energizing the appropriate electrodes the signal may be applied to any one of the output circuits from electrodes 2-10. Two layers of chessboard pattern areas may be provided, each portion of semi-conductor material being contiguous with one of the opposite conductivity type. Specifications 592,260, 632,942, [both in Group XXXVI], 632,980, [Group XL (c)], 694,021, 694,029, 700,232, 700,236 and 708,241, [Group XXXVI], are referred to.