| 摘要 |
PURPOSE:To synthesize the remodulated waves within one conversion cycle with coincidence in time axis, and to improve the linearity of conversion, by dividing the input digital data into two parts to convert the high-order bit data into a pulse amplitude modulated wave with the low-order bit data converted into a pulse width modulated wave respectively. CONSTITUTION:The serial data DIN fed from a data input terminal 1 is converted into the parallel data DP by an S/P conversion part 2 and then divided into high-order nP bits and low-order nL bits respectively. These nP and nL bits are supplied to a PAM control part 3 and a PWM control part 4 respectively, and the 1-bit data DS of logic 1 is supplied to an auxiliary data input terminal 5 of the part 4. Then control signals SPAM and SPWM symmetrical in pulse conversion are supplied to a modulation part 10 from parts 3 and 4 respectively. The signals are processed by constant current sources 14-16 and 18, switches 11-13 and 17 of the part 10 and an operational amplifying part 20. Then the PAM wave is converted into a pulse amplitude modulated wave, and the PWM wave is converted into a pulse width modulated wave. The continuity is secured between both PAM and PWM waves. |
