| 摘要 |
PURPOSE:To reduce the number of externally mounted components to an integrated circuit and to reduce the cost by integrating a preamplifier, a differentiation device, a differentiation constant setting device and a switch element into a circuit, mounting externally a low pass filter to the said integrated circuit and using the switching element so as to change over the filter element. CONSTITUTION:The preamplifier 3, the differentiation device 4, the differentiation constant setting device and the switch element are integrated in the integrated circuit, the low pass filter 5 is mounted externally to the integrated circuit, the switching element and the filter element mounted externally to the integrated circuit or built in the integrated circuit constitute a switching filter 6 and the switching element switches the filter elements. That is, at least the switching element and the differentiation constant setting device in the switching filter 6 are formed in the integrated circuit and the filter constant is switched by turning on/off the switching element in the inside of the integrated circuit. Thus, number of externally mounted components is decreased and it is not required to provide a control signal at the outside of the integrated circuit and the constitution is simplified. |
