Measuring strain gages is one of the big challenges for sensor technology, especially the weighing industry. Due to the small excitation of the strain gages on a load cell of only 0.2 % (2000 ppm) full scale, and due to the high resolution of 16 Bit and more, the resistors must be measured with a precision deeply in the ppb range. Reasonably, this can only be done measuring the ratio of the resistors.
Here the Â® measuring principle is breaking new grounds compared to A/D converters. The ratio of the resistors is ascribed to a time interval measurement, not to a voltage difference like in Wheatstone bridges. The sensor's resistors together with a capacitor act as low-pass filters. The capacitor, charged to Vcc, is discharged through the sensor's resistors. The discharge time to trigger level (selectable) is precisely measured by a TDC (Time-to-Digital Converter).
The Â® integrated circuits are realized without any analog component. Again, acam uses its TDC technology to set new standards in circuit design.