公开(公告)号：US3611353A

公开(公告)日：1971-10-05

申请号：US3611353D

申请日：1969-03-26

Applicant: BECKMAN INSTRUMENTS INC

Inventor： SHIPP RICHARD E ,  SMITH GEORGE W

IPC: H03M1/80 ,  H03M1/00 ,  H03K13/02

CPC classification number: H03M1/00 ,  H03M1/22

Abstract: This disclosure relates to a digital-to-analog converter having digital integrated circuit switches in place of the heretoforeused analog switches. A multiplicity of digital input leads are connected to at least one digital integrated circuit having a plurality of digital transistor switches. A multiplicity of resistors are connected between a common terminal and the digital switches. In order to accommodate the use of digital switches in the place of analog switches, a compensating reference voltage source is connected to the digital integrated circuit and also to a reference input of an analog operational amplifier. The signal input of the operational amplifier is connected to the common terminal of the resistors. By selective operation of the digital switches, the various resistors are connected between the compensating voltage reference source and the signal input of the operational amplifier. The currents produced thereby are summed by the operational amplifier to produce an analog output voltage in proportion to the current sum. The compensating reference voltage source in the circuit configuration disclosed allows the use of digital integrated circuit switches heretofore not possible.