Circuit and method for calibrating the phase shift between a plurality of digitizers in a data acquisition system

摘要

The analog-to-digital conversion circuit for high-frequency data acquisition system comprises a plurality of digitizers (6, 9) capable of sampling and digitizing a high-frequency analog input signal (a; w1), the sampling times of the different digitizers being phase-shifted, and a circuit (3, 4, 5, 8, 11) for calibrating the phase shift between a first digitizer and a second digitizer. The phase shift calibration circuit (3, 4, 5, 8, 11) determines a phase shift correction value (u) so as to minimize the difference between a sequence of digital values (r_i) determined by the first digitizer (6) and a sequence of corresponding digital values (u_i) determined by interpolating the digital values (s_i) supplied by the second digitizer (9). The value u can be calculated according to the following equation: $\mathop{\mathrm{image}}$ u=p\·\frac{\underset{i}{\∑}\⁢\text{\ }\⁢\left(r_i-s_i\right)\·\left(s_i-s_{i-1}\right)}{\underset{i}{\∑}\⁢\text{\ }\⁢\left(s_i-s_{i-1}\right)\·\left(s_i-s_{i-1}\right)}$$;wherein p represents the sampling period, r_i represents the value supplied by the first digitizer (6) at the time i and s_i the value supplied by the second digitizer (9) at the corresponding sampling time.