What is a D/A converter?
D/A conversion methods
Numerous implementation methods exist for D/A converters.
1. Using Resistors
Resistance elements are the most easy-to-use analog elements on the LSI.
The relative accuracy is also comparatively good, making it possible to achieve 10bit precision without trimming.
Selecting the appropriate resistance makes it possible to cover a wide range, from low to high speeds.
2. Using capacitors
In general, because using capacitance results in better accuracy than resistance, it is the preferred method for medium and high precision D/A converters.
However, ensuring high accuracy requires a large capacitance, leading to longer charge/discharge times. Plus, high-speed operation is problematic.
In addition, to compensate for leakage current at low frequencies, refresh is required, which complicates operation.
3. Using current
Adopted in conversion systems for high-speed (several MHz) applications. Output current switching is performed by switching the current source based on digital input.
Resistors and an operational amplifier are utilized to convert the output current to voltage.
4. Oversampling method
A conversion method used for high accuracy (16bit~) applications.
This method filters a low-resolution, high sampling rate to obtain the desired analog signal.
Generally, a 1bit digital sigma system consists of a low pass filter and binary output (0, 1).