Parameter Adjustment
Post-fabrication adjustment alters internal circuit parameters to compensate for manufacturing process variations. In analog integrated circuits, a non-volatile trim allows permanent correction of offset voltages, reference currents, and sensor gains.
Silicon Configuration
Programming non-volatile memory elements within the chip modifies resistor strings or capacitor arrays. During the production test phase, the non-volatile trim is executed by applying high-voltage pulses to floating-gate transistors or metal fuses. This action permanently locks the correction code into the device registers.
It enables precise electrical tuning without requiring manual potentiometer adjustments.
Precision Limit
Achieving high precision in voltage references depends on the resolution and range of the adjustment circuitry. If the step size of the non-volatile trim is too large, the output voltage cannot be brought to its nominal target. Conversely, if the adjustment range is too narrow, the trim cannot compensate for severe wafer-level process shifts.
Balancing these two requirements is a primary task of the circuit designer.
Stability Assessment
Long-term stability measurements trace the retention of programmed coefficients over time and temperature. Because a non-volatile trim can degrade due to charge loss in memory cells, high-temperature baking is used to accelerate potential failures. Devices that exhibit drift beyond specified tolerances during this stress test are rejected before shipment.
This reliability screen guarantees that the calibrated parameters remain stable over the operating life of the sensor.
