Digital-to-Analog Conversion

When data is in binary form, the 0's and 1's may be of several forms such as the TTL form where the logic zero may be a value up to 0.8 volts and the 1 may be a voltage from 2 to 5 volts. The data can be converted to clean digital form using gates which are designed to be on or off depending on the value of the incoming signal. Data in clean binary digital form can be converted to an analog form by using a summing amplifier. For example, a simple 4-bit D/A converter can be made with a four-input summing amplifier. More practical is the R-2R Network DAC.

Four-Bit D/A Converter

One way to achieve D/A conversion is to use a summing amplifier.

R-2R Ladder DAC

The summing amplifier with the R-2R ladder of resistances shown produces the output 如图所示的R-2R梯形电阻求和放大器产生输出 where the D's take the value 0 or 1. The digital inputs could be TTL voltages which close the switches on a logical 1 and leave it grounded for a logical 0. This is illustrated for 4 bits, but can be extended to any number with just the resistance values R and 2R. 其中D的取值为0或1。数字输入可以是TTL电压，逻辑1时闭合开关，逻辑0时则接地。这示例展示了4位的情况，但只需用电阻值R和2R即可扩展到任何数量。 More Detail 更多细节

R-2R Ladder DAC Details

Thevenin Example: R-2R Ladder