Direct digital frequency synthesizer using hybrid digital to analog converter and synthesizing method thereof
AssigneeChung-Ang University-Academy Cooperation Foundation
InventorsKwang-Hyun Baek, Hong Chang Yeoh, Jae-Hun Jung, Yun-Hwan Jung
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Abstract
A direct digital frequency synthesizer and a synthesizing method thereof. The direct digital frequency synthesizer uses a hybrid digital to analog converter, which matches output data of a phase accumulator to a sine wave amplitude using a hybrid DAC, including a non-linear DAC and a linear DAC. The non-linear DAC outputs a direct base point current using some bits of output data of a phase accumulator, causing the linear DAC to output a gradient current based on gradient information generated using other bits of the output data of the phase accumulator. These currents are summed for the analog output.
Claims13
A direct digital frequency synthesizer using a hybrid digital to analog converter, comprising:
- a hybrid DAC (digital to analog Converter) that includes a non-linear DAC part for generating a current corresponding to base points in a non-linear manner, and a linear DAC part for generating a current corresponding to a gradient for linear approximation, which interconnects the base points, and sums and outputs the currents of the DAC parts;
- and
- a PAM (phase to amplitude mapper) that provides upper first data of output data of an external phase accumulator to the non-linear DAC part of the hybrid DAC, generates a gradient using the first data and lower second data of the output data, and provides the generated gradient to the linear DAC part of the hybrid DAC.
A direct digital frequency synthesizing method using a hybrid digital to analog converter, comprising:
- a data division step of dividing an output of a phase accumulator into first data for base point designation and second data for linear approximation;
- a base point mapping step of directly providing the first data to a non-linear DAC of a hybrid DAC including the non-linear DAC and a linear DAC;
- a gradient generation step of generating binary values for a gradient for linear approximation using the second data and the first data and providing the generated binary values to the linear DAC;
- and
- a conversion step of generating base point currents in the non-linear DAC by connecting a non-linear current source corresponding to the first data to the non-linear DAC, and generating and summing expansion gradient currents corresponding to the gradient binary values in the linear DAC.
Dependencies are inferred from the claim text.