| Following the progress in technology described by Moore's law, CMOS technologies continue to provide an exponential growth in computational power. The ability to integrate ever more digital processing onto a silicon die, however, has not always translated into performance gains for analog or mixed-signal circuitry. The continuing increases in digital processing power do provide analog and mixed-signal circuit designers with opportunities to leverage digital signal processing to ease some analog circuit design requirements. This dissertation explores the design of a digital-to-analog converter for wireless transmitter applications. By designing the digital signal processing together with the analog interface circuitry, the analog circuit requirements are relaxed while only relatively minor increases in the power and area consumed by the digital circuitry are incurred.; Transmitters for wireless communications often employ architectures in which digital baseband quadrature signals are first converted to analog baseband quadrature signals and then filtered and mixed to an intermediate frequency (IF). This architecture suffers from two major problems, mismatches among the analog components in the I and Q paths lead to I/Q mismatch, and DC offsets in the D/A converters cause carrier leak. One means of eliminating both I/Q channel mismatch and carrier leak is to digitally mix the baseband I and Q signals to IF and then use a bandpass D/A converter to generate the analog IF signal.; This dissertation presents the design of a bandpass oversampled digital-to-analog converter in which the mixing to IF is performed in the digital domain. In this work, digital and semi-digital filters are integrated into the D/A converter to suppress the out-of-band quantization noise generated by cascaded digital noise shaping.; By designing the digital noise shaping, IF Mixing, D/A conversion and out-of-band noise suppression in concert, it has been possible to achieve a dynamic range of 83 dB for a signal bandwidth of 6.25 MHz centered at an IF of 50 MHz. |
