A latch architecture for driving unit current cell of a current-steering digital-to-analog
converter (DAC) which reduces the drain-source voltage variation of the output
current-source transistors and reduces the coupling of unwanted injection of input
digital signals as well as clock signals is presented herein. Moreover, this latch
helps to achieve lower glitch during code transition with improved dynamic performance.
The latch effectively uses the intrinsic RC delay of most transistors within the
latch architecture in order to achieve optimal crossing points of complementary
control signals. Unwanted input injection or cross-talk is reduced by introducing
transistors (904, 906, 932 and 934) that are off during code transitions
without compromising the DAC update speed. Conflicts between currently held and
new inputs are avoided in an effort to reduce the harmonic distortion. Furthermore,
the distortion as a result of the clock signal fed through each transistor in the
first and second subcircuit portions cancel each other.