Voltage Generator With Adjustable Slope

Abstract

A charging circuit includes a first current mirror for receiving an input voltage, a second current mirror including a first branch circuit and a second branch circuit for receiving the input voltage, a switch transistor coupled to the first current mirror and the first branch circuit for determining a conduction condition of the switch transistor according to a switch signal, a first resistor including a first resistance and one end coupled to the switch transistor, and a second resistor including a second resistance and one end coupled the second branch circuit of the second current mirror, wherein the first current mirror and the second current mirror perform a charging operation of a loading circuit according to the first resistance and the second resistance.

What is claimed is: 
     
         1 . A charging circuit comprising:
 a first current mirror for receiving an input voltage;   a second current mirror coupled to the first current mirror and comprising a first branch circuit and a second branch circuit for receiving the input voltage;   a switch transistor coupled to the first current mirror and the first branch circuit of the second current mirror for determining a conduction condition of the switch transistor according to a switch signal;   a first resistor comprising a first resistance, one end coupled to the switch transistor and another end grounded; and   a second resistor comprising a second resistance, one end coupled to the second branch circuit of the second current mirror and another end grounded;   wherein the first current mirror and the second current mirror are utilized to process a charging operation of a load circuit according to the first resistance as well as the second resistance.   
     
     
         2 . The charging circuit of  claim 1 , wherein a first conduction current and a second conduction current pass through the first branch circuit and the second branch circuit of the second current mirror, and the first resistance as well as the second resistance are utilized to transform the first conduction current and the second conduction current into a first output voltage and a second output voltage, so as to process the charging operation of the load circuit. 
     
     
         3 . The charging circuit of  claim 1 , wherein the charging operation comprises to generate at least a charging slope for the load circuit. 
     
     
         4 . The charging circuit of  claim 3 , wherein a conduction condition of the switch transistor is utilized to generate the charging slope. 
     
     
         5 . The charging circuit of  claim 3 , wherein a ratio formed by the first resistance and the second resistance is utilized to adjust a slope change of the charging slope. 
     
     
         6 . The charging circuit of  claim 5 , wherein the slope change of the charging slope is utilized to adjust a charging period of the charging operation. 
     
     
         7 . The charging circuit of  claim 3 , wherein the charging slope comprises a single slope value without turning points. 
     
     
         8 . The charging circuit of  claim 1 , wherein the first current mirror comprises a first P-type MOS transistor and a second P-type MOS transistor, and the second current mirror comprises a third P-type MOS transistor and a fourth P-type MOS transistor. 
     
     
         9 . The charging circuit of  claim 8 , wherein the switch transistor is an N-type MOS transistor comprising a gate coupled to a drain of the second P-type MOS transistor, a drain coupled to a drain of the third P-type MOS transistor, and a source coupled to the first resistor. 
     
     
         10 . The charging circuit of  claim 1 , wherein the first current mirror further comprises a third conduction current and is coupled to the load circuit, and the third conduction current is utilized to process the charging operation of the load circuit. 
     
     
         11 . The charging circuit of  claim 1 , wherein the load circuit is a MOS transistor capacitor, a polysilicon capacitor or a passive circuit. 
     
     
         12 . The charging circuit of  claim 1 , wherein the charging operation provides a soft start operation for the load circuit.