7.3.3 Analog Input Over-Range Recovery Error

An over-range condition occurs if the analog input voltage exceeds the full-scale range of the converter (0dBFS). To test recovery from an over-range, the ADC analog input is injected with a sinusoidal input frequency exactly at CLKIN/4 (a four-point sinusoid at the digital outputs). The four sample points of each period occur at the top, mid-scale, bottom and mid-scale of the sinusoid (clipped by the ADC when over-ranged to all 0s or all 1s). Once the amplitude exceeds 0dBFS, the top and bottom of the sinusoidal input becomes out of range, while the mid-scale point is always in-range and measureable with ADC output codes. The graph in Figure 27 indicates the amount of error from the expected mid-scale value of 2048 that occurs after negative over-range (bottom of sinusoid) and positive over-range (top of sinusoid). This equates to the amount of error in a valid sample 1 clock cycle after an over-range occurs, as a function of input amplitude.

Figure 27. Recovery Error 1 Clock Cycle After Over-Range vs Input Amplitude