| 摘要 |
PURPOSE:To prevent the accumulation of errors of many multiplying circuits by detecting the maximum value of the control signal which controls the gain of a digital signal and adding the minimum until 1 to the output signal of a multiplier for output. CONSTITUTION:A digital signal is supplied from a terminal 1, and a gain control signal is supplied from a terminal 2. When both signals are set at the maximum value FF (hexadecimal), a detector 4 detects the maximum value FF of the control signal and supplies a high level to a switch 7. The switch 7 selects and delivers 1. For an adder 5, the multiplication result (FFXFF=FE01) of a multiplier 3 needs 16 bits and 01 is defined as an error as long as the result of multiplication is defined s 8 bits. However 1 is added to the FF of the multiplication result and therefore the FF is delivered. As a result, no addition is carried out with accumulation of errors for a multiplying circuit having its control input set at maximum 1 despite a multi-stage connection of such multiplying circuits. |
