Booster circuit

Abstract

Power source voltage is supplied to a boost driver of a booster circuit. The boost driver generates a pulse signal when a boost-starting signal indicative of start of boost is input. A boost capacitor boosts voltage level of an output terminal when the pulse signal is received. A precharge circuit supplies voltage to the output terminal on standby before boosting. A constant-voltage generating circuit supplies constant voltage to the precharge circuit.

What is claimed is:  
     
         1 . A booster circuit, comprising: 
 an output terminal;    a boost driver to which power source voltage is supplied, said boost driver generating a pulse signal when a boost-starting signal indicative of start of boost is input;    a boost capacitor which boosts voltage level of said output terminal when said pulse signal is received;    a precharge circuit which supplies voltage to said output terminal on standby before boosting; and    a constant-voltage generating circuit which supplies constant voltage to said precharge circuit.    
     
     
         2 . A booster circuit, comprising: 
 an output terminal;    a boost driver which generates a pulse signal when a boost-starting signal indicative of start of boost is input;    a boost capacitor which boosts voltage level of said output terminal when said pulse signal is received;    a precharge circuit to which power source voltage is supplied, said precharge circuit supplying voltage to said output terminal on standby before boosting; and    a constant-voltage generating circuit which supplies constant voltage to said boost driver.    
     
     
         3 . A booster circuit, comprising: 
 an output terminal;    a boost driver which generates a pulse signal when a boost-starting signal indicative of start of boost is input;    a boost capacitor which boosts voltage level of said output terminal when said pulse signal is received;    a precharge circuit which supplies voltage to said output terminal on standby before boosting; and    a constant-voltage generating circuit which supplies constant voltage to said boost driver and said precharge circuit.    
     
     
         4 . A booster circuit according to    claim 1   , wherein 
 said precharge circuit comprises: 
 a field-effect transistor whose source is connected to said constant-voltage generating circuit and whose drain is connected to said output terminal; and  
 a control circuit which controls electric potential of a gate of said field-effect transistor in association with said boost-starting signal.  
   
     
     
         5 . A booster circuit according to    claim 1   , wherein 
 said boost driver comprises: 
 a first field-effect transistor whose gate inputs an inverted signal of said boost-starting signal, said power source voltage being supplied to a source of said first field-effect transistor; and  
 a second field-effect transistor whose source is grounded and whose drain is connected to a drain of said first filed-effect transistor, a gate of said second field-effect transistor inputting an inverted signal of said boost-starting signal, and a conductive type of a channel of said second field-effect transistor being different from that of said first field-effect transistor.  
   
     
     
         6 . A booster circuit according to    claim 2   , wherein 
 said precharge circuit comprises: 
 a field-effect transistor whose drain is connected to said output terminal, said power source voltage being supplied to a source of said field-effect transistor; and  
 a control circuit which controls electric potential of a gate of said field-effect transistor in association with said boost-starting signal.  
   
     
     
         7 . A booster circuit according to    claim 2   , wherein 
 said boost driver comprises: 
 a first field-effect transistor whose source is connected to said constant-voltage generating circuit, a gate of said first field-effect transistor inputting an inverted signal of said boost-starting signal; and  
 a second field-effect transistor whose source is grounded and whose drain is connected to a drain of said first filed-effect transistor, a gate of said second field-effect transistor inputting an inverted signal of said boost-starting signal, and a conductive type of a channel of said second field-effect transistor being different from that of said first field-effect transistor.  
   
     
     
         8 . A booster circuit according to    claim 3   , wherein 
 said precharge circuit comprises: 
 a first field-effect transistor whose source is connected to said constant-voltage generating circuit and whose drain is connected to said output terminal; and  
 a control circuit which controls electric potential of a gate of said first field-effect transistor in association with said boost-starting signal; and  
   said boost driver comprises: 
 a second field-effect transistor whose source is connected to said constant-voltage generating circuit, a gate of said second field-effect transistor inputting an inverted signal of said boost-starting signal; and  
 a third field-effect transistor whose source is grounded and whose drain is connected to a drain of said second filed-effect transistor, a gate of said third field-effect transistor inputting an inverted signal of said boost-starting signal, and a conductive type of a channel of said third field-effect transistor being different from that of said second field-effect transistor.