| 摘要 |
PROBLEM TO BE SOLVED: To provide a delta-sigma modulation circuit that, if an output of the delta-sigma modulation circuit is saturated, can prevent an oscillating state, return to a normal operation quickly when a normal operating range is recovered, and maintain an analog-digital conversion operation in the meantime.SOLUTION: A delta-sigma modulation circuit 42 includes: an nth order loop filter comprising n (n≥3) integrators 11, 12, 13 connected in a cascade; a quantizer 17; and at least one digital-analog converter 14, 15, 16 for inputting an output of the quantizer into one of the integrators. At least n-2 of the n integrators constituting the loop filter comprise amplifiers 23, 24, 25 having a low pass filter characteristic. A determination is made as to whether or not an output of the loop filter is saturated, and if saturation is detected, the amplifiers are changed for the low pass characteristic and the order of the loop filter is reduced from the nth order to the first or second order. |
