| Summary: | Digital to analog converter (DAC) is one of the important elements in the
communication circuits. In this project, a digital to analog converter which operates
with 1.8V voltage supply is implemented based on 0.18μm Silterra CMOS process
technology. The implemented digital to analog converter is an 8-bit parallel inputs R-2R
architecture converter. The digital to analog converter operates with a reference voltage
and provides a current output. An operational amplifier is connected at the output end of
the R-2R network to convert the output current to suitable output voltage. This
operational amplifier is a current mirror op-amp with open loop dc voltage gain of
24.64dB. Besides, this op-amp achieves bandwidth of 21.5MHz, with the power
consumption of 0.85mW. The mentioned reference voltage is established by another
circuit block which known as bandgap reference voltage circuit. This bandgap reference
voltage circuit is simply composed of CMOS transistors, op-amp, resistors and diodes.
The overall D/A converter circuit has the settling time 8ns, which means the data
sampling rate of 125MHz, with power consumption of 31.356mW. The schematic entry
and simulation of the whole DAC circuits is done using the software Cadence, Virtuoso
and Spectre.
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