Adjustment device with shift amount control circuit

Abstract

A decibel level adjustment device that calculates an output signal that is a d decibel multiple of an input signal comprises a plurality of shift circuits, a shift amount control circuit, and adders. The shift circuits shift an input signal by exactly a designated number of bits in a designated direction. The shift amount control circuit receives the value of d as a decibel control value, and in accordance with this decibel control value, generates and outputs control signals that indicate the number of bits to shift and the shift direction of each shift circuit. The adder adds the outputs of the shift circuits.

What is claimed is:  
     
         1 . A decibel level adjustment device for calculating an output signal which is a d decibel multiple of an input signal, comprising: 
 a plurality of shift means arranged parallel to each other for shifting said input signal exactly a designated number of bits in a designated direction;    a shift amount control circuit means for receiving the value of said d as a decibel control value and, in accordance with said decibel control value, for generating and outputting a control signal indicating the direction and number of bits of shifting of each of said shift means; and    adder means for adding the outputs of said shift circuits together.    
     
     
         2 . A device according to  claim 1 , further comprising an additional shift means for shifting the output of said addition means exactly a designated number of bits in a designated direction; 
 wherein said shift amount control circuit means generates and outputs a control signal indicating the shift direction and number of bits of shifting of said additional shift means.    
     
     
         3 . A device according to  claim 1 , wherein said shift means is a barrel shifter.  
     
     
         4 . A device according to  claim 2 , wherein said shift means is a barrel shifter.  
     
     
         5 . A decibel level adjustment device for calculating an output signal which is a d decibel multiple of an input signal, comprising: 
 a plurality of signal lines arranged parallel to each other for producing in advance signals that are shifted a number of bits necessary for operating on said input signal;    at least one switch means for selecting outputs of said plurality of signal lines or all “0”;    a switch control circuit means for receiving the value of said d as a decibel control value and, in accordance with said decibel control value, switching said switch or switches; and    an adder circuit means for adding together the outputs of said switch or switches and output of said signal lines that does not pass by way of said switch or switches.