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(四)调谐电压的产生微处理器IX0933CE内设有调谐电压数据数/模(D/A)转换电路。它将中央运算器最后运算所得的数字信号通过D/A电路转换成脉宽调制信号。通过积分变换电路输出高频调谐器所需的模拟调谐电压。 D/A转换电路由一个14位锁存器和一个14位脉宽调制器等单元组成,它是一组系数乘法器。在一定的周期内,输出的脉冲数等于锁存的二进制数。14位D/A变换电路用作分频时,最大分频系数为2~(14)(16384),分频系数的大小受14位数码的控制。作为D/A变换器的系数乘法器,既可以分频,也可以将分频后的各脉冲进行叠加。IC1002脚33、34
(D) the tuning voltage generation Microprocessor IX0933CE is equipped with tuning voltage data number / mode (D / A) conversion circuit. It will be the final operation of the central computing unit digital signal through the D / A circuit into a pulse width modulation signal. The integrated tuning circuit outputs the analog tuning voltage required by the high frequency tuner. D / A conversion circuit by a 14-bit latch and a 14-bit pulse width modulator and other units, it is a set of coefficient multipliers. In a certain period, the number of pulses output is equal to the binary number latched. 14-bit D / A converter circuit for frequency division, the maximum frequency factor of 2 to (14) (16,384), the size of the frequency divider by 14-bit digital control. As the coefficient multiplier of the D / A converter, either the frequency can be divided or the divided pulses can be superposed. IC1002 feet 33,34