For mobile devices, reducing power draw and prolonging
battery life are critical design objectives. Presently, current-steering digital
to analog converters (DACs) require high power consumption and dynamic element
matching and are vulnerable to component source mismatch. Accordingly, large
rail devices and higher supply voltages are needed. Additionally, DACs do not
provide quantization noise suppression and are forced to rely on RF filtering
for out of band noise suppression. These power-hungry converters are complex and
limit the operational performance of many wireless devices.
Researchers at Arizona State University have developed a new
radio frequency finite impulse response DAC for use in mobile communications
devices and low power sensors. The circuit features high immunity to current
source mismatch, allowing the use of smaller rail devices and the downscaling of
the supply voltage. The circuit is highly linear due to a single-bit sigma-delta
DAC and significantly reduces power consumption due to the elimination of
dynamic element matching. The circuit is suitable for adaptation to deep
submicron CMOS technologies, due to use of small current sources and a reduced
need for cascade impedance boosting transistors. Additionally, the circuit
provides quantization noise suppression and does not depend on RF filtering for
out of band noise suppression. Signal to noise ratio is improved, valuable die
space is preserved, and power draw is significantly reduced. A highly efficient,
high-performance RF DAC is now available.
Potential Applications
- Mobile Communications Devices
- Wireless Sensors
- General Digital to Analog Conversion
Benefits and Advantages
- Reduced Power – The circuit draws up to 50% less power
than current approaches, prolonging battery life.
- Reduced Size – The circuit can be up to 5x smaller,
preserving valuable die space.
- Improved Performance – Integrated noise suppression and
the elimination of RF filtering allow a greater signal to noise ratio.
- Immunity to Current-source Mismatch – Smaller rail
devices and lower supply voltages can now be used.
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