For the purposes of this D/A introductory course, the on-chip D/As have been divided into two categories: low-resolution types that typically have 8-bits of resolution, and high-resolution types that typically have 12- to 14-bits of resolution. The low-resolution types (the most common) generally are either the scaled-resistor or scaled-current-source designs shown here, or the R-2R ladder designs. (Again, the high-resolution PWM type will be detailed in another presentation.) All of the low-resolution D/A designs have one thing in common: resistors. Resistors are a basic technology challenge for MCU manufacturers because it is very difficult to make accurate resistances with the process technology used to build high-speed microcontrollers. Hence, on-chip MCU D/As typically have “multiple” least significant bits (LSBs) of error over their temperature and operating voltage ranges. Fortunately, 8-bit resolution is adequate for approximately 90% of all embedded system applications. It should be pointed out that it is possible to produce precision scaled-resistor, scaled-current-source and R-2R ladder on-chip D/A designs. One way to do this is to individually laser trim the resistors to ensure conformance to tight specifications. However, this production technique increases device cost.