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STUDIES ON CMOS DIGITAL-TO-ANALOG CONVERTERS
【文件名】:081012@52RD_STUDIES ON CMOS DIGITAL-TO-ANALOG CONVERTERS.rar
【格 式】:rar
【大 小】:3280K
【简 介】:
【目 录】:
Abstract
In this thesis we present an overview and study on digital-to-analog converters (DAC), mainly
for communications applications. Especially, we look at some digital subscriber line (DSL)
specifications and communication over twisted-pair channels. It is pointed out that the required
resolution on the DACs in such systems is in the order of 12 to 14 bits of resolution. At the
same time the bandwidth stretches from below MHz to several tens of MHz. These figures are
the guiding specification throughout the thesis.
In this work we consider many of converter architectures and chips. The current-steering DAC
is pointed out as a suitable converter for both high speed and high resolution. We also investigate
the oversampling DAC (OSDAC) and discuss its properties in detail.
The performance of the converters is limited by both static and dynamic errors. The static
errors are usually caused by mismatch of the components and limit the accuracy at low speed.
The static performance is often described by measures of differential and integral nonlinearities,
(DNL and INL). For communication applications these measures are not especially used
for characterization of the DACs. Instead, the dynamic errors, such as settling errors, glitches,
etc., are more important since they increase with higher sample rates and signal frequencies.
To analyze the effect of errors it is usually easier to consider the DAC’s behavior in frequency
domain using measures, such as the spurious-free dynamic range (SFDR) and signal-to-noiseand-
distortion ratio (SFDR). These measures are normally derived from the output spectrum
when a sinusoidal input signal is used. In some applications it may be necessary to use several
sinusoidal tones to get relevant measures. Two common measures are the multi-tone power
ratio (MTPR) and the peak-to-average ratio (PAR). The PAR of the input signal affects the
maximum signal-to-noise ratio (SNR) of the converter and a small PAR is preferred since it
maximizes the SNR............................ |
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