RATIOMETRISCHER KONVERTER

摘要

A ratiometric converter includes first and second A/D converters (36, 38). The latter receives an input signal voltage from a load cell (10) on sense lines (12) and (14) and compares it with an internal reference. Similarly, the first converter (36) receives the reference voltage to the load cell (10) and compares it with the internal reference. The outputs of the converters (36) and (38) are then input to subtraction circuits (78) and (84), respectively, in the digital domain. In a calibration mode, switches (72) and (73) short the reference nodes in the load cell (10) together to determine the non- ratiometric offsets VOFF1-4. These offsets are stored in registers (80) and (86) for the reference and input voltages, respectively. During operation, the offsets are input to subtraction blocks (78) and (84) and a digital subtraction performed on the outputs of both converters. The outputs of the subtraction blocks (78) and (84) are input to a ratio metric operator block (52) to perform a digital division thereon. This results in a ratiometric output that has the non-ratiometric offsets removed. Thereafter, the signal is input to a system calibration block (32) to remove ratiometric errors.