Mediatek Singapore Pte. Ltd.

Nathan Egan

Stacy Ho

Gerhard Mitteregger

Timothy Perrin Fisher-Jeffes

Boyi Zheng

Techniques for compensating high-speed digital-to-analog converters (DACs) for static mismatch are described. In ideal circumstances, the current sources of a DAC are identical to each other, leading to a frequency response presenting a relatively flat noise spectrum. In the presence of mismatch, however, the response creates unwanted spurious content, which can negatively affect the DAC's dynamic range. The techniques described herein involve randomized thermometric encoders. First, the direction in which a packet contracts or expands, depending on the value to be encoded, can be randomized. Second, pairs of values in a packet (and/or pairs of values outside the packet) can be swapped with one another in a randomized fashion. Third, the decision of whether to apply randomization or not can itself be randomized. By applying one or more of the randomization techniques described herein, the negative effects of switch timing offset and errors in DC linearity can be mitigated.

Noise shaping in digital-to-analog converters using randomizing encoders

A digital to analog (DAC) circuit that performs least significant bit (LSB) dithering comprises: a first DAC; an auxiliary code generator configured to produce an auxiliary code; an auxiliary DAC configured to receive the auxiliary code and convert the auxiliary code into an analog version of the auxiliary code; and summing circuitry to dither LSBs of the first DAC with the auxiliary code. The auxiliary code generator is configured to update the auxiliary code at a rate less than a sampling rate of the DAC circuit, the auxiliary code has a smaller range than that of a range of binary-weighted LSBs of the main DAC and/or the auxiliary code generator is configured to produce the auxiliary code as a predetermined repeating sequence.

LSB dithering for segmented DACs

A digital-to-analog converter (DAC) capable of operating in radio frequency (RF) with linear output, low distortion, low power consumption, and input data independence. The DAC includes switch drivers and output switches driven by the switch drivers. The switch drivers include pairs of outputs, and positive feedback circuitries coupled between respective pairs of outputs. The output switches are arranged between a first current source configured to push current to the DAC's outputs and a second current source configured to pull current from the DAC's outputs. Different output switches are configured to push current to and pull current from the DAC's outputs in accordance with rising edges and falling edges, respectively.

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San Jose, CA, United States of America

Nathan Egan