| 摘要 |
PURPOSE:To relieve the setting load of a current ratio by counting a clock pulse in response to a digital data in the unit of leading and trailing of the clock pulse so as to decrease the ratio of the setting current ratio. CONSTITUTION:A counter circuit 20A counts the clock pulse CLK in the unit of leading and trailing in response to a digital input and applies the count of two-count for one period T of the clock CLK so as to give '0' or an even number when the least significant bit LSB of a digital input Dil is '0', for example, and give an odd number when the LSB is '1', thereby decreasing the count time. The counter circuit 20A switches a switch 4A to supply a constant current IA from a constant current source 6A to an integration device 8, where the signal is subject to integration. Thus, for example the current ratio (IA:IB) of constant current sources 6A, 6B is decreased at the same clock frequency of a conventional DA converter to relieve the load of the current ratio setting.
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