Wide dynamic range delta sigma analog-to-digital converter with precise gain tracking

A delta sigma analog-to-digital architecture assures that all channels in a multi-element receiver follow the same compression and/or time-gain variation curve. This is accomplished by varying the reference voltage as a function of time so that the full scale range and associated quantization noise are large at the beginning of the receiving interval and become smaller as more distant echoes arrive. All channels follow the identical gain curve since all channels have the same reference voltage at the same time. The distribution of time-varying reference voltages may be done by using analog buses or by employing a timevarying digital code that specifies the reference voltages derived from a digital-to-analog (D/A) converter. In the latter case, corrections can be applied to the code at each channel.