Invention Grant
- Patent Title: Techniques to reduce harmonic distortions of impedance attenuators for low-power wideband high-resolution DACs
- Patent Title (中): 降低低功耗宽带高分辨率DAC阻抗衰减器谐波失真的技术
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Application No.: US13839763Application Date: 2013-03-15
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Publication No.: US08872685B2Publication Date: 2014-10-28
- Inventor: Tongyu Song , Sang Min Lee , Derui Kong , Dongwon Seo
- Applicant: QUALCOMM Incorporated
- Applicant Address: US CA San Diego
- Assignee: QUALCOMM Incorporated
- Current Assignee: QUALCOMM Incorporated
- Current Assignee Address: US CA San Diego
- Agency: Arent Fox LLP
- Main IPC: H03M1/00
- IPC: H03M1/00 ; H03M1/74

Abstract:
A digital-to-analog converter (DAC) includes, in part, a multitude of input stages that supply currents to a pair of current summing nodes in response to a digital signal, and an impedance attenuator coupled between the current summing nodes and the output of the DAC. The impedance attenuator is adapted, among other function, to increase the range of impedances of the output load, to account for changes in the output load impedance due to variations in the process, voltage and temperature, and to decouple the impedances seen by the summing nodes from the load impedance. The impedance attenuator further includes a differential-input, differential-output amplifier with programmable common-mode gain bandwidth to control the harmonic distortion of the amplifier. The impedance attenuator optionally includes a pair of cross-coupled capacitors to control the harmonic distortion of the amplifier.
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