a data processing apparatus, for converting a test pattern into a test output according to a test firmware trim value received under a calibration mode, and for converting a non-test pattern to a non-test output according to a target firmware trim value stored therein under a normal mode, wherein the test output is an analog signal; and

a calibration apparatus, coupled to the data processing device, for calibrating the data processing apparatus, the calibration apparatus analyzing the test output to tune the test firmware trim value outputted to the data processing device, and for controlling the data processing device to store a specific test firmware trim value as the target firmware trim value when an analysis result of the test output generated in reference to the specific test firmware trim value indicates that a predetermined criterion is met, the calibration apparatus comprising:

an analysis device, for analyzing the test output to generate the analysis result, the analysis device comprising an analog-to-digital converter (ADC) for sampling the analog signal to generate the analysis result; and

a micro-controller, coupled to the analysis device, for processing the analysis result to adjust the test firmware trim value;

wherein the analysis result outputted from the ADC includes at least a first sample value sampled during a first period of the analog signal and at least a second sample value sampled during a second period of the analog signal; and the micro-controller determines a difference value according to at least the first sample value and the second sample value, and then compares the difference value with a reference value to determine if the predetermined criterion is met.