Differential input buffer with auxiliary bias pulser circuit

Abstract

An integrated circuit clock buffer is described which includes a pulser circuit having a delayed feedback to provide a pulsed signal in response to a transition in the external clock signal. The pulser circuit includes a delay element having an output node coupled to the input node of an inverter. The delay element and inverter are coupled between a first and second transistor. The buffer circuit generates non-skewed internal clock signals.

What is claimed as new and desired to be protected by Letters Patent of the United States is:  
     
         1 . A buffer circuit comprising: 
 a first input node for receiving a digital signal;    a controllable buffer circuit coupled to the first input node responsive to an enable signal, the controllable buffer circuit providing an output signal in response to the digital signal when the enable signal is in a first state, and the controllable buffer circuit being disabled when the enable signal is in a second state, said buffer circuit having a bias node; and    a pulser circuit coupled to said bias node for providing a pulse signal to said bias node in response to said enable signal switching to said first state.    
     
     
         2 . The buffer circuit of  claim 1  wherein the controllable buffer circuit is a differential buffer circuit.  
     
     
         3 . The buffer circuit of  claim 1  wherein said pulser circuit comprises a first and second transistor connected in series between said bias node and a source of potential, said first transistor directly receiving said enable signal at a gate thereof, said second transistor receiving said enable signal at a gate thereof after it passes through at least a delay element.  
     
     
         4 . The buffer circuit of  claim 3  wherein said first transistor is on and said second transistor is off while said enable signal is in a second state.  
     
     
         5 . The buffer circuit of  claim 3  wherein said first transistor is off and said second transistor is on while said enable signal is in a first state.  
     
     
         6 . The buffer circuit of  claim 3  wherein said pulser circuit creates a pulse when said enable signal returns to said first state.  
     
     
         7 . The buffer circuit of  claim 3  wherein said pulser circuit further comprises an inverter connected to said delay element.  
     
     
         8 . The buffer circuit of  claim 1  wherein said pulser circuit pulses the bias node toward ground to help said node reach a stable voltage position.  
     
     
         9 . The buffer circuit of  claim 1  wherein said digital signal is a clock signal.  
     
     
         10 . The buffer circuit of  claim 3  wherein a delay time of said delay element is adjustable.  
     
     
         11 . The buffer circuit of  claim 10  wherein said delay time is about 3 to 5 nanoseconds.  
     
     
         12 . A memory device comprising: 
 a memory array containing a plurality of memory cells; and    a buffer circuit comprising: 
 a first input node for receiving a digital signal;  
 a controllable buffer circuit coupled to the first input node responsive to an enable signal, the controllable buffer circuit providing an output signal in response to the digital signal when the enable signal is in a first state, and the controllable buffer circuit being disabled when the enable signal is in a second state said buffer circuit having a bias node; and  
 a pulser circuit coupled to said bias node for providing a pulse signal to said bias node in response to said enable signal switching to said first state.  
   
     
     
         13 . The memory device of  claim 12  wherein the controllable buffer circuit is a differential buffer circuit.  
     
     
         14 . The memory device of  claim 12  wherein said pulser circuit comprises a first and second transistor connected in series between said bias node and a source of potential, said first transistor directly receiving said enable signal at a gate thereof, said second transistor receiving said enable signal at a gate thereof after it passes through at least a delay element.  
     
     
         15 . The memory device of  claim 14  wherein said first transistor is on and said second transistor is off while said enable signal is in a second state.  
     
     
         16 . The memory device of  claim 14  wherein said first transistor is off and said second transistor is on while said enable signal is in a first state.  
     
     
         17 . The memory device of  claim 14  wherein said pulser circuit creates a pulse when said enable signal returns to said first state.  
     
     
         18 . The memory device of  claim 14  wherein said pulser circuit further comprises an inverter connected to said delay element.  
     
     
         19 . The memory device of  claim 12  wherein said pulser circuit pulses the bias node toward ground to help said node reach a stable voltage position.  
     
     
         20 . The memory device of  claim 12  wherein said digital signal is a clock signal.  
     
     
         21 . The memory device of  claim 14  wherein a delay time of said delay element is adjustable.  
     
     
         22 . The memory device of  claim 21  wherein said delay time is about 3 to 5 nanoseconds.  
     
     
         23 . The memory device of  claim 12  wherein said memory device forms part of a memory module.  
     
     
         24 . A processor based system comprising: 
 a central processing unit;    a memory device coupled to said central processing unit to receive data from and supply data to said central processing unit, said memory device comprising: 
 a buffer circuit comprising: 
 a first input node for receiving a digital signal;  
 a controllable buffer circuit coupled to the first input node responsive to an enable signal, the controllable buffer circuit providing an output signal in response to the digital signal when the enable signal is in a first state, and the controllable buffer circuit being disabled when the enable signal is in a second state said buffer circuit having a bias node; and  
 a pulser circuit coupled to said bias node for providing a pulse signal to said bias node in response to said enable signal switching to said first state.  
 
   
     
     
         25 . The processor based system of  claim 24  wherein the controllable buffer circuit is a differential buffer circuit.  
     
     
         26 . The processor based system of  claim 24  wherein said pulser circuit comprises a first and second transistor connected in series between said bias node and a source of potential, said first transistor directly receiving said enable signal at a gate thereof, said second transistor receiving said enable signal at a gate thereof after it passes through at least a delay element.  
     
     
         27 . The processor based system of  claim 26  wherein said first transistor is on and said second transistor is off while said enable signal is in a second state.  
     
     
         28 . The processor based system of  claim 26  wherein said first transistor is off and said second transistor is on while said enable signal is in a first state.  
     
     
         29 . The processor based system of  claim 26  wherein said pulser circuit creates a pulse when said enable signal returns to said first state.  
     
     
         30 . The processor based system of  claim 26  wherein said pulser circuit further comprises an inverter connected to said delay element.  
     
     
         31 . The processor based system of  claim 24  wherein said pulser circuit pulses the bias node toward ground to help said node reach a stable voltage position.  
     
     
         32 . The processor based system of  claim 24  wherein said digital signal is a clock signal.  
     
     
         33 . The processor based system of  claim 26  wherein a delay time of said delay element is adjustable.  
     
     
         34 . The processor based system of  claim 33  wherein said delay time is about 3 to 5 nanoseconds.  
     
     
         35 . A method of reducing clock skew comprising the acts of: 
 buffering a digital signal when an enable signal is in a first state and discontinuing said buffering when an enable signal is in a second state, said buffering operation relying on a bias potential;    providing a pulse voltage level as said bias potential in response to said enable signal switching to said first state.    
     
     
         36 . The method of  claim 35  wherein said digital signal is a clock signal.  
     
     
         37 . A method of reducing clock skew comprising the acts of:: 
 providing a first input node for receiving a digital signal;    providing a controllable buffer circuit coupled to the first input node responsive to an enable signal, the controllable buffer circuit providing an output signal in response to the digital signal when the enable signal is in a first state, and the controllable buffer circuit being disabled when the enable signal is in a second state, said buffer circuit having a bias node; and    providing a pulser circuit coupled to said bias node for providing a pulse signal to said bias node in response to said enable signal switching to said first state.    
     
     
         38 . The method of  claim 37  wherein said pulser circuit comprises a first and second transistor connected in series between said bias node and a source of potential, said first transistor directly receiving said enable signal at a gate thereof, said second transistor receiving said enable signal at a gate thereof after it passes through at least a delay element.  
     
     
         39 . The method of  claim 38  wherein said first transistor is on and said second transistor is off while said enable signal is in a second state.  
     
     
         40 . The method of  claim 38  wherein said first transistor is off and said second transistor is on while said enable signal is in a first state.  
     
     
         41 . The method of  claim 37  wherein said pulser circuit creates a pulse when said enable signal returns to said first state.  
     
     
         42 . The method of  claim 37  wherein said pulser circuit pulses the bias node toward ground to help said node reach a stable voltage position.  
     
     
         43 . The method of  claim 37  wherein said digital signal is a clock signal.  
     
     
         44 . The method of  claim 38  wherein a delay time of said delay element is adjustable.  
     
     
         45 . The method of  claim 44  wherein said delay time is about 3 to 5 nanoseconds.