| 摘要 |
900,366. Semi-conductor gating circuits; pulse code modulation circuits. STANDARD TELEPHONES & CABLES Ltd. April 28, 1961 [May 4, 1960], No. 15660/60. Classes 40 (5) and 40 (6). A gating and storage circuit includes a gating pair of tunnel diodes 1, 2 and a storage pair of tunnel diodes 3, 4, the diodes of each pair being serially connected with like polarity to voltage sources B, C. The voltage sources are controlled so that an input signal applied to a common connection of the elements of the gating pair at predetermined instants will set the gating pairs into one of two stable states, which is then transferred to the storage pair, and so that except at these instants the gating pair present a low impedance shunt across the input signal. The input at A is derived from the coder of a pulse modulation system and may be either a positive (MARK) or negative (SPACE) pulse, Fig. 2 (a), and the voltage applied to B comprises positive-going sampling pulses, Fig. 2 (b), so that a MARK on A switches diode 2 to its high state, with a corresponding change in potential at X, Fig. 2 (c). The input at C, Fig. 2 (d), causes the data to be transferred to the storage pairs at the end of the sampling period, and removal of the sampling pulse from B allows the gating pair to put a low impedance shunt across input A to shunt spurious signals between the sampling periods. Read-out signals, Fig. 2 (e), are applied at D and the resulting output, Fig. 2 (9), has its positive-going part clipped by a diode (not shown). The two tunnel diodes of each pair may be different portions of a multiple junction semi-conductor device. In a pulse code modulation communication system, each element of the binary data corresponding to the amplitude of a signal at the sampling time is fed to a circuit of the type shown in Fig. 1, and the outputs of the circuits are connected together. The read-out pulses are applied to each circuit at appropriate times to produce a sequence output of pulses. Specification 847,334 is referred to. |
