Semiconductor apparatus, oscillation circuit, and signal processing system

Abstract

A semiconductor apparatus includes: first and second external terminals that are connected to respective both ends of an piezoelectric vibrator, in which the piezoelectric vibrator is externally disposed; an inverting amplifier that is disposed between the first and second external terminals; a feedback resistance that feeds back an output of the inverting amplifier to an input of the inverting amplifier; a first capacitative element that is disposed between the first external terminal and a reference voltage terminal; a first resistive element that is disposed in series with the first capacitative element; a second capacitative element that is disposed between the second external terminal and the reference voltage terminal; and a second resistive element that is disposed in series with the second capacitative element.

What is claimed is: 
     
         1 . A semiconductor apparatus comprising:
 first and second external terminals that are connected to respective both ends of an piezoelectric vibrator, the piezoelectric vibrator being externally disposed;   an inverting amplifier that is disposed between the first and second external terminals;   a feedback resistance that feeds back an output of the inverting amplifier to an input of the inverting amplifier;   a first capacitative element that is disposed between the first external terminal and a reference voltage terminal; and   a second capacitative element that is disposed between the second external terminal and the reference voltage terminal, wherein   the inverting amplifier comprises:
 a constant current source circuit that is disposed between a first power supply terminal and an output terminal; 
 a switched transistor that is disposed between the output terminal and a second power supply terminal and controlled to be on or off according to an input of the inverting amplifier; 
 a first internal capacitative element that is disposed in series with the switched transistor; and 
 a first internal resistive element that is disposed in parallel with the first internal capacitative element. 
   
     
     
         2 . The semiconductor apparatus according to  claim 1 , further comprising:
 a second internal capacitative element that is disposed in series with the constant current source circuit; and   a second internal resistive element that is disposed in parallel with the second internal capacitative element.   
     
     
         3 . The semiconductor apparatus according to  claim 1 , wherein
 each of the first and second capacitative elements is a variable capacitative element.   
     
     
         4 . The semiconductor apparatus according to  claim 3 , further comprising:
 a plurality of the inverting amplifiers that are disposed in parallel with each other; and   a plurality of gain switches that are connected in series with the respective plurality of the inverting amplifiers.   
     
     
         5 . The semiconductor apparatus according to  claim 4 , wherein
 at least one of the plurality of gain switches is switched on.