Elbert Bechthum

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The switching characteristics of Digital to Analog Converter (DAC) unit elements can limit DAC dynamic performance at high speeds [1]. Unbalances and mismatches in clock, data and output networks create a non-identical environment for every current cell. Together with mismatch in current cell switching transistors and other non-idealities, this causes the(More)
In an RF transmitter, the function of the mixer and the DAC can be combined in a single block: the Mixing-DAC. For the generation of multicarrier GSM signals in a basestation, high dynamic linearity is required, i.e. SFDR>85dBc, at high output signal frequency, i.e. fout ≈ 4GHz. This represents a challenge which cannot be addressed efficiently by current(More)
This paper presents a new foreground DAC calibration method that is insensitive to temperature fluctuations and on-chip disturbances. In the proposed current cell, the same number of unit transistors is always used, guaranteeing matched response for all current cells. These transistors are divided in two groups: a fixed group and a configurable group. The(More)
In current steering Mixing-DACs with local mixing, timing errors between the current cells is a major concern. This paper considers two types of random timing errors: delay and duty-cycle. Analysis shows that the Mixing-DAC is sensitive to delay errors, but much less sensitive to duty-cycle errors. For the required high spectral purity of future 4GHz(More)
A major limitation of the linearity of Current Steering (CS) RF-DACs is the large output voltage swing (typically 1V<sub>pp</sub>), which couples to sensitive internal nodes and thereby causes non-linear distortion. This paper proposes a novel approach for the linearization of the CS RF-DAC. An output transformer decouples the output from the circuit core(More)
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