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How is the reference current of a DAC created?
DAC is a voltage-output device, so an external voltage-to-current (V/I) stage is added to the design. To implement the V/I stage, create an accurate reference current that is amplified using a current mirror. Laser-diode applications generally require a precisely controlled current to regulate the output power. An
What can a DAC converter be used for?
Digital-to-analog converters (DACs) find application in many systems, including communication trans – mitters and consumer electronics.
How is the tail cur-rent steered in a DAC?
Here, the tail cur- rent is steered to the left or the right by each differential pair, causing only a small voltage excursion at node X. Also, since the total array current is relatively constant, the ground bounce is much smaller. Of course, another advantage of this configuration is that it naturally provides differential outputs.
How many channels are in a 16 bit DAC?
The device features eight DAC channels at 16-bit resolution that can be set to either a 1.25-V, 2.5-V, or 5-V range while using the internal reference. This DAC is a voltage-output device, so an external voltage-to-current (V/I) stage is added to the design.
Why do we need a multi-channel DAC?
Multi-channel, multi-range DACs provide two attributes: they allow summing of the outputs for higher overall current, along with optimal matching of each channel’s resolution to the application. In this way, effective resolution is maximized rather than wasted by using only part of the DAC dynamic range.
How many bits does a current output DAC need?
Using a 14-bit, 100 mA range with a current-output DAC for 0 to 25 mA drive would provide only 12 bits of effective resolution, wasting 2 bits. For this reason, the AD5770R and LTC2662 offer different spans for their multiple outputs.
How are DACS used in analog to digital converters?
DACs are often incorporated into digital systems in which real-world signals are digitized by analog-to-digital converters (ADCs), processed, and then converted back to analog form by DACs. In these systems, the performance required of the DACs will be influenced by the capabilities and requirements of the other components in the system.
How does segmentation affect the linearity of DACS?
Segmentation has the added benefit of reducing the number of resistors (or current sources)required to achieve a given resolution, allowing smaller die sizes. Thus, it is common for high-resolution DACs to be segmented. Overall linearity is still determined by the matching of individual elements.