Wednesday, 8 February 2012

Op Amp Digital to Analog Converter Circuit

Op Amp Digital to Analog Converter Circuit

This is a design of the simple 4-bit digital-to-analog converter.  It is actually just a variant of a simple op amp summer circuit, i.e., an operational amplifier configured to output a voltage that is proportional to the sum of the input voltages. Here’s the figure of the circuit;

In this circuit, the inputs are binary weighted with respect to each other, with the binary weighting of the inputs achieved by the R-2R ladder resistor network at the non-inverting input of the op-amp. As its name implies, the R-2R network consists of resistors with only two values, R and 2R (10K and 20K, respectively, in the circuit shown).  The input SN to bit N is '1' if it is connected to a voltage VR and '0' if it is grounded. The number of bits of this DAC may be increased by connecting more switches with corresponding R/2R resistors.

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