Patent ID: 7282953

Claim:
A pre-buffer level shifter, comprising: a switchable current source for receiving a first data signal and determining whether to provide a current to a first current terminal or to a second current terminal according to the first data signal; a current mirror having a first current terminal and a second current terminal, wherein the first current terminal of the current mirror is coupled to the first current terminal of the switchable current source and the second current terminal of the current mirror for outputting a second data signal is coupled to the second current terminal of the switchable current source; a buffer unit for outputting a third data signal coupled to the second current terminal of the current mirror; a first clamping circuit for clamping the voltage swing of the second data signal coupled to the second current terminal of the current mirror; a second clamping circuit for clamping the voltage swing of the third data signal coupled to the buffer unit; and a controllable switch having a control terminal, a first terminal and a second terminal, wherein the first terminal is coupled to the output terminal of the buffer unit for determining whether to connect a voltage at its second terminal to its first terminal according to the first data signal at the control terminal thereof.