GB1263094A - Improvements in or relating to digital-to-analogue converters - Google Patents

Abstract

1,263,094. Digital/analogue converter. ROSEMOUNT ENG. CO. Ltd. 9 June, 1970 [10 June, 1969], No. 29384/69. Heading G4H. In a digital/analogue converter in which a digital input signal is converted using shift register 10 (Fig. 1) to a pulse train, the pulse train being sampled, the results of the samples are averaged to give an analogue output signal of amplitude proportional to the digital input. In the embodiment of Fig. 1 which utilizes a shift register as in Specification 1,227,829 the shifting of a binary coded signal in shift register 10 and the enabling of AND gate 15 by a JK flip-flop 16 are controlled such that on output lead 21 each bit of the signal appears a number of times corresponding to its significance to control a switch 26 which when operated connects a resistor 27 and capacitor 28 to a reference voltage source 26. The D.C. output across capacitor 28 then has an average value proportional to the input. In the embodiment of Fig. 2 the gate is replaced by a JK flip-flop (30, not shown). In a further modification the flip-flop (30) is replaced by a D flip-flop (40, Fig. 3, not shown).