Programmable Analog-To-Digital and Digital-To-Analog Converter Circuit
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
By setting a digital/analog (DA) switch, a converter circuit becomes analog-to-digital (A-D) or digital-to-analog (D-A). Elements of the converter circuit, shown in the figure, must meet the following criteria: 1. Sample-and-hold capacitor 2 must hold a signal for a full A-D conversion cycle. 2. Comparator 4 must have accuracy of at least 10 mV for an A-D design for 8 bits and a 0-5 V range (approximately 1/2 of a least significant bit (LSB) value). 3. Control logic 6 is a combinatorial logic that performs successive approximation for A-D conversion and is attached to register 8. 4. Multiplexer 10 is two way, multiplexing bits from INBITS with output bits from register 8, and is controlled by input DA. 5. Register 12 is a clocked register. 6.