Analog Devices,inc.

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Richard Schreier

Khiem Quang Nguyen

Lawrence A Singer

Jennifer Lloyd

Susan Mary Dacy

Mismatch-shaping for a digital-to-analog converter (DAC) involves allocating elements from an element array to multiple DAC channels. Various state variables are used to keep track of element usage, and the number of state variables is preferably less than the number of elements in the element array. The element array may be treated like a bi-directional circular array, in which case the array elements may be allocated to the two DAC channels as needed in opposite directions with reference to a common anchor point such that the array elements for each channel are contiguous within the circular array. All array elements are available for allocation to both DAC channels, although no array element can be allocated to both DAC channels simultaneously. A collision resolution scheme is used to prevent overlapping allocations of array elements. Pointers may be used to keep track of the array elements allocated to each channel, making implementation relatively simple.

Mismatch-shaping for a quadrature digital-to-analog converter

A mixing DAC includes an analog output network; a current source; a current switching circuit connected between the current source and the analog output network; a switch driver circuit responsive to a digital input at a first rate and a clock signal having a predetermined period for driving the current switching circuit to selectively interconnect the current source and the analog output network; and a waveform generator for driving the current source to produce an output current including a plurality of peaks at a second rate during each clock period to up-convert the response energy of the DAC analog output to approximately the second rate.

Mixing digital to analog converter

A multi-bit sigma-delta analog to digital converter has a quantizer, a loop filter circuit, and a digital to analog feedback circuit. The quantizer, loop filter, and digital to analog feedback circuit have a loop gain associated therewith. The quantizer and loop filter have a combined gain associated therewith. The full-scale of the digital to analog feedback circuit is varied. The combined gain of the quantizer and loop filter is also varied. More specifically, the combined gain of the quantizer and loop filter is varied in inverse proportion to the full-scale of the digital to analog feedback circuit to maintain the loop gain at a substantially constant level.

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Richard Schreier