During operation of a SAR ADC, several of the MSBs can be preloaded with predetermined bit decisions prior to carrying out bit trials. A system and method can be provided for incrementally preloading the predetermined bit decisions such as to maintain voltages present at comparator inputs within a limited range of acceptable input voltages.

During operation of a SAR ADC, several of the MSBs can be preloaded with predetermined bit decisions prior to carrying out bit trials. A system and method can be provided for incrementally preloading the predetermined bit decisions such as to maintain voltages present at comparator inputs within a limited range of acceptable input voltages.

A current source device having a current source array includes a plurality of current source units, a plurality of least significant bits, and a plurality of most significant bits. The current source units are arranged along a plurality rows and columns of a current source array. Each of the least significant bits includes a first amount of current source units is placed at the geometric center of the current source array. Each of the most significant bits includes a second amount of current source units. The second amount is the first amount multiplied by a positive integer. The two adjacent bits in the most significant bits are centrally symmetrical to the geometric center.

A current source device having a current source array includes a plurality of current source units, a plurality of least significant bits, and a plurality of most significant bits. The current source units are arranged along a plurality rows and columns of a current source array. Each of the least significant bits includes a first amount of current source units is placed at the geometric center of the current source array. Each of the most significant bits includes a second amount of current source units. The second amount is the first amount multiplied by a positive integer. The two adjacent bits in the most significant bits are centrally symmetrical to the geometric center.

An apparatus and a method for digital-analog conversion are provided. The apparatus includes a first cell matrix for outputting a current of a signal corresponding to a number of Most Significant Bits (MSBs) of an input digital signal, a second cell matrix for outputting a current of a signal corresponding to a number of Least Significant Bits (LSBs) of the input digital signal, an amplifier for amplifying the output current of the second cell matrix at a preset amplification, and an adder for adding the output current of the first cell matrix and the output current of the amplifier.

A bit error rate testing method includes: sampling, by an analog-to-digital converter circuit, a symmetric signal to generate output digital codes; identifying a starting digital code in the output digital codes; storing the starting digital code and first digital codes, which follow the starting digital code in the output digital codes, into a first register circuit in an order as second digital codes, in which the starting digital code and the first digital codes correspond to one cycle of the symmetric signal; storing the starting digital code and the first digital codes into a second register circuit in a reversed order; shifting the starting digital code and the first digital codes in the second register circuit to generate third digital codes; and determining a bit error rate of the analog-to-digital converter circuit according to a difference between a corresponding second digital code and a corresponding one third digital code.