| 摘要 |
A volume control or amplitude varying system for digital signals includes a cascade connection of a coarse multiplier/divider (18') for changing the values of digital signals in 6 dB steps and a fine multiplier/divider (20') for changing the values of digital values logarithmically in substantially equal steps of less than 6 dB per step. The coarse multiplier/divider selectively multiplies the digital signal by powers of 2. The fine multiplier/divider is a scaling circuit which multiplies the digital signal by predetermined values, an ascending/decending sequence of which form a substantially logarithmic sequence. Both serial-bit and parallel-bit embodiments are described. Suitable for use in the fine multiplier/divider in a serial-bit embodiment, the invention also provides a bit-serial scaling apparatus including a cascade connection of signal combining circuits (60,62,66) in which a delay (58,64) of at least one bit period is provided by or between the combining circuits, and means (68-74) for selectively coupling an applied bit-serial signal to second input terminals of the combining circuits, their first input terminals being included in the cascade connection. |
