Sensor adjusting circuit

Abstract

A sensor adjusting circuit for adjusting a digital sensor, whose circuit scale is small and which can maintain high accuracy in a wide adjustment range is provided. A sensor adjusting circuit for adjusting an analog input signal inputted from a sensor and outputting it as another analog output signal in accordance with a physical quantity to be sensed, comprises: a first analog-to-digital converter having an analog integrator ( 2 ) for integrating the analog input signal, a comparator ( 3 ) for comparing an output of the analog integrator with a predetermined value, and a D/A converter ( 7 ) for outputting an output of the comparator as the input signal; and a second digital-to-analog converter ( 5 ) for converting the output of the comparator and outputting it as the analog output signal.

What is claimed is:  
     
         1 . A sensor adjusting circuit for adjusting an analog input signal inputted from a sensor in accordance with a physical quantity to be sensed and outputting the analog input signal as another analog output signal, comprising: 
 a first analog-to-digital converter having an analog integrator for integrating said analog input signal, a comparator for comparing an output of said analog integrator with a predetermined value, and a D/A converter for outputting an output of said comparator as said input signal; and    a second digital-to-analog converter for D/A converting the output of said comparator and outputting resultant data as said analog output signal.    
     
     
         2 . A circuit according to  claim 1 , further comprising an operational unit for digitally processing the output of said comparator and outputting resultant data to said second digital-to-analog converter.  
     
     
         3 . A sensor adjusting circuit comprising an analog-to-digital converter, an operational unit for processing an output of said analog-to-digital converter by a prestored program, and a writable memory for holding data for adjustment, 
 wherein said analog-to-digital converter is constructed by an oversampling analog-to-digital converter including an analog integrator, a comparator, and a digital-to-analog converter, and    said oversampling analog-to-digital converter is constructed to generate an output having the number of bits which is equal to or lower than an accuracy required by a sensor as an object in a cycle which is equal to or faster than {fraction (1/10)} of a response cycle required by said sensor.    
     
     
         4 . A sensor adjusting circuit comprising an analog-to-digital converter, an operational unit for processing an output of said analog-to-digital converter by a prestored program, and a writable memory for holding data for adjustment, 
 wherein said analog-to-digital converter is constructed by an oversampling analog-to-digital converter including an analog integrator, a comparator, and a digital-to-analog converter, and    said oversampling analog-to-digital converter has conversion accuracy of 4 or 8 bits.    
     
     
         5 . A sensor adjusting circuit comprising an analog-to-digital converter, an operational unit for processing an output of said analog-to-digital converter by a prestored program, and a writable memory for holding data for adjustment, 
 wherein said analog-to-digital converter is constructed by an oversampling analog-to-digital converter including an analog integrator, a comparator, and a digital-to-analog converter, and    said oversampling analog-to-digital converter constructs a part of a sensor circuit of a sensor as an object.    
     
     
         6 . A sensor adjusting circuit comprising an analog-to-digital converter, an operational unit for processing an output of said analog-to-digital converter by a prestored program, and a writable memory for holding data for adjustment, 
 wherein said analog-to-digital converter is constructed by an oversampling analog-to-digital converter including an analog integrator, a comparator, and a digital-to-analog converter,    said oversampling analog-to-digital converter generates an output having the number of bits which is equal to or less than an accuracy required by a sensor as an object in a cycle which is equal to or faster than {fraction (1/10)} of a response cycle required by said sensor, and    an average value of outputs of said operational unit satisfies the requirement of said sensor.    
     
     
         7 . A circuit according to any one of  claims 3  to  6 , 
 wherein said operational unit is operated by a cyclic program which cycles from address 0 to address of the maximum counting value of a program counter so that a reset upon turn-on of a power source is unnecessary.  
 
     
     
         8 . A circuit according to any one of  claims 3  to  6 , 
 wherein said writable memory which holds data for adjustment has an error correction logic and an error detection logic.  
 
     
     
         9 . A digital sensor adjusting circuit for adjusting an output of a sensor for sensing a physical quantity by processing the output of the sensor with prestored data for characteristic adjustment, comprising: 
 an analog integrator for integrating and outputting an output of said sensor;    a comparator for converting outputs of said analog integrator into digital signals of level 1 and 0;    a 1-bit D/A converter for converting an output of said comparator into an analog signal and outputting the analog signal; and    a subtracter for subtracting an output of said 1-bit D/A converter from an input of said analog integrator,    wherein the output of said comparator is processed with said prestored data for characteristic adjustment, thereby adjusting an output of said sensor.    
     
     
         10 . A digital sensor adjusting circuit for adjusting an output of a sensor for sensing a physical quantity by a numerical process by a prestored program, comprising: a ROM for storing a program; a RAM for temporarily storing data; an accumulator for temporarily storing data for data transfer; a data bus for connecting at least said accumulator and said RAM; and a program counter for controlling execution of a program, 
 wherein said program counter is always counted up except for a subtrahend due to an overflow and    said ROM for storing programs is connected to a data bus different from said data bus.    
     
     
         11 . A digital sensor adjusting circuit for adjusting an output of a sensor for sensing a physical quantity by a numerical operation of a prestored program, comprising: a ROM for storing a program; a RAM for temporarily storing data; an accumulator for temporarily storing data for data transfer; a data bus for connecting at least said accumulator and said RAM; and at least two program counters for controlling execution of a program, 
 wherein means for controlling the program counter which is valid at present is provided.    
     
     
         12 . A digital sensor adjusting circuit for adjusting an output of a sensor for sensing a physical quantity by a numerical process of a prestored program, comprising: a ROM for storing a program; a RAM for temporarily storing data; an accumulator for temporarily storing data for data transfer; a data bus for connecting at least said accumulator and said RAM; and an operational unit for executing a numerical operation, 
 wherein said operating unit is connected to said data bus.    
     
     
         13 . A digital sensor adjusting circuit for adjusting an output of a sensor for sensing a physical quantity by a numerical process of a prestored program, comprising: a ROM for storing a program; a RAM for temporarily storing data; an accumulator for temporarily storing data for data transfer; a data bus for connecting at least said accumulator and said RAM; and an operational unit for executing a numerical operation, 
 wherein writing to said accumulator is inhibited according to an internal state of said operational unit.