Bonnie Baker

Overview

Acquisition Time The acquisition time for the SAR converter is the time required for the sampling mechanism to capture one input voltage for one digital output ( Figure A-1) The acquisition time for the delta-sigma converter lasts during the time that multiple samples are acquired for one digital output.

Figure A-1: (a) Chip select (CS) falls, the converter powers up and starts to sample. (b) The falling edge of the clock closes the sample switch and the converter starts to convert the signal

Average Noise Floor In a Fast Fourier Transform (FFT) representation of converter data, the average noise floor is a calculated root-sum-square (rss) combination of all the bins within the FFT plot, excluding the input signal and signal harmonics.

Bipolar Input Mode (Single-Ended or Differential Inputs) An input range that uses two input pins and allows negative and positive analog inputs. A negative input is the difference between the two input pins. In this configuration, neither pin goes below or above the power supply rails.

Code Width The voltage difference between two transition points. The ideal code width is equal to 1 LSB. See Figure A-2.

Figure A-2: The ideal transfer function has zero offset error, zero gain error, zero DNL error, and zero INL error

Common-Mode Rejection (CMR) The degree of rejection of a common-mode signals (ac or DC) across the differential input stage.

Conversion Time After sampling the signal, the conversion time is the time required...