| 摘要 |
1,250,625. Analogue/digital converter. INTERNATIONAL BUSINESS MACHINES CORP. 16 Oct., 1968 [15 Nov., 1967], No. 49012/68. Heading G4H. In an analogue/digital converter of the type in which an analogue input current is compared with a variable reference current, a current flows continuously in each of a plurality of current paths 66, 68, 70, 72 (Fig. 2), the currents being selectively directed into the comparator. In the embodiment of Fig. 2 analogue voltage inputs 1-n are converted into corresponding currents and time multiplexed by a control 16 selectively rendering non-conductive transistors 42 so that the currents are sequentially applied to terminal 40. The analogue/digital converter includes logic circuitry 54 responsive to the output of comparators 50 controlling a register 56 from which the digital data is taken and transistors 90-96 which when rendered non- conductive direct the currents flowing through binary weighted resistors 74-80 in the associated current paths 66-72 via diodes 98-104 to the comparator 50. When a transistor is conductive the associated diode is reverse biased to prevent current flow through it. In the embodiment of Fig. 3 the parallel resistor network is replaced by a ladder, the current from a source 120 selectively flowing either through transistors 140-146 controlled by the logic circuitry 54 or diodes 150-156 to the comparator 50. |
