Circuit for transforming signals varying between different voltages

Abstract

An interface circuit for transforming a first signal varying between a low voltage and a high voltage into a second signal varying between a lower voltage and a higher voltage, the low voltage being equal to the lower voltage and the higher voltage being greater than the high voltage, including an inverter circuit receiving the first signal and being connected to a higher voltage source through first diodes and being directly connected to the lower voltage, each of the first diodes having a threshold voltage; a conversion and storage element formed of first and second inverters head-to-tail supplied between said higher and lower voltages, the first inverter receiving the output of the inverter circuit and providing the second signal; wherein the number of said first diodes is such that the difference between the higher voltage and the high voltage is smaller than or equal to the sum of the threshold voltages of said first diodes.

1 . An interface circuit for transforming a first signal varying between a low voltage and a high voltage into a second signal varying between a lower voltage and a higher voltage, the low voltage being equal to the lower voltage and the higher voltage being greater than the high voltage, comprising: 
 an inverter circuit receiving the first signal and being connected to a higher voltage source through first diodes and being directly connected to the lower voltage, each of the first diodes having a threshold voltage;    a conversion and storage element formed of first and second inverters head-to-tail supplied between said higher and lower voltages, the first inverter receiving the output of the inverter circuit and providing the second signal;    wherein the number of said first diodes is such that the difference between the higher voltage and the high voltage is smaller than or equal to the sum of the threshold voltages of said first diodes.    
   
   
       2 . An interface circuit for transforming a first signal varying between a low voltage and a high voltage into a second signal varying between a lower voltage and a higher voltage, the lower voltage being smaller than the low voltage and the high voltage being equal to the higher voltage, comprising: 
 an inverter circuit receiving the first signal and being connected to a lower voltage source through first diodes and being directly connected to the higher voltage, each of the first diodes having a threshold voltage;    a conversion and storage element formed of first and second inverters head-to-tail supplied between said higher and lower voltages, the first inverter receiving the output of the inverter circuit and providing the second signal;    wherein the number of said first diodes is such that the difference between the low voltage and the lower voltage is smaller than or equal to the sum of the threshold voltages of said first diodes.    
   
   
       3 . A level shifter, comprising: 
 a first and second power-supply nodes respectively operable to receive low and high supply voltages;    a first inverter having an input node, an output node, a first supply node coupled to the first power-supply node, and a second supply node, the input node operable to receive an input signal having a high-voltage level that is less than the high supply voltage and having a low-voltage level that is less than the high-voltage level;    a first diode chain coupled between the second power-supply node and the second supply node of the first inverter, the first diode chain having a first threshold greater than or equal to the difference between the high supply voltage and the high-voltage level;    a second inverter having an input node coupled to the output node of the first inverter, an output node, and first and second supply nodes respectively coupled to the first and second power-supply nodes; and    a third inverter having an input node coupled to the output node of the second inverter, an output node coupled to the input node of the second inverter, and first and second supply nodes respectively coupled to the first and second power-supply nodes.    
   
   
       4 . The level shifter of  claim 3  wherein the first diode chain comprises a single diode.  
   
   
       5 . An integrated circuit, comprising: 
 a level shifter that comprises, 
 first and second power-supply nodes respectively operable to receive low and high supply voltages,  
 a first inverter having an input node, an output node, a first supply node coupled to the first power-supply node, and a second supply node, the input node operable to receive an input signal having a high-voltage level that is less than the high supply voltage and having a low-voltage level that is less than the high-voltage level,  
 a first diode chain coupled between the second power-supply node and the second supply node of the first inverter, the first diode chain comprising a plurality of serially-connected diodes and having a first threshold greater than or equal to the difference between the high supply voltage and the high-voltage level,  
 a second inverter having an input node coupled to the output node of the first inverter, an output node, and first and second supply nodes respectively coupled to the first and second power-supply nodes, and  
 a third inverter having an input node coupled to the output node of the second inverter, an output node coupled to the input node of the second inverter, and first and second supply nodes respectively coupled to the first and second power-supply nodes.  
   
   
   
       6 . An electronic system, comprising: 
 an integrated circuit, comprising, 
 a level shifter that comprises, 
 first and second power-supply nodes respectively operable to receive low and high supply voltages,  
 a first inverter having an input node, an output node, a first supply node coupled to the first power-supply node, and a second supply node, the input node operable to receive an input signal having a high-voltage level that is less than the high supply voltage and having a low-voltage level that is less than the high-voltage level,  
 a first diode chain coupled between the second power-supply node and the second supply node of the first inverter, the first diode chain comprising a plurality of serially-connected diodes and having a first threshold greater than or equal to the difference between the high supply voltage and the high-voltage level  
 a second inverter having an input node coupled to the output node of the first inverter, an output node, and first and second supply nodes respectively coupled to the first and second power-supply nodes, and  
 a third inverter having an input node coupled to the output node of the second inverter, an output node coupled to the input node of the second inverter, and first and second supply nodes respectively coupled to the first and second power-supply nodes.  
 
   
   
   
       7 . A method, comprising: 
 inverting with an inverter circuit an input signal having a high voltage that corresponds to a first logic level and having a low voltage that corresponds to a second logic level to generate an output voltage, the inverter circuit coupled to a high supply voltage through a diode chain having a threshold greater than or equal to the difference between the high supply voltage and the high voltage; and    if the input signal has the high voltage, forcing the output voltage to a lower voltage than the low voltage such that substantially zero quiescent current flows in the inverter circuit; and    if the input signal has the low voltage, forcing the output voltage to a higher voltage than the high voltage such that substantially zero quiescent current flows in the inverter circuit.    
   
   
       8 . The method of  claim 7  wherein: 
 forcing the output voltage to a lower voltage comprises forcing the output voltage to the lower voltage with a latch; and    forcing the output voltage to a higher voltage comprises forcing the output voltage to the higher voltage with the latch.