Double bootstrapped clock buffer circuit
AssigneeFujitsu Limited
InventorFumio Baba
Life of this patent
Estimating the term…
Abstract
A buffer circuit has first and second boot-strap circuits. The first boot-strap circuit charges the gate of an output MOS transistor to a voltage above a supply voltage when an input signal has a first logic level. The gate of a precharging MOS transistor in the first boot-strap circuit is driven by the second boot-strap circuit so as to precharge a capacitor in the first boot-strap circuit to a voltage above the supply voltage when the input signal has a second logic level.
Claims6
A buffer circuit, operatively connected to a supply voltage and to receive an input signal, producing an output signal in response to the input signal, comprising:
- first and second output transistors having their drain-source current paths operatively connected in series between the supply voltage and ground, thereby forming a junction between said first and second output transistors, each of said first and second output transistors having a gate;
- an output terminal operatively connected to the junction between said first and second output transistors;
- a first boot-strap circuit operatively connected to the gate of said first output transistor for charging the gate of said first output transistor to a charged voltage above the supply voltage when the input signal has a first logic level, turning on said first output transistor and charging said output terminal to the supply voltage, said first boot-strap circuit comprising:
- a capacitor operatively connected to the gate of said first output transistor;
- and
- a precharging transistor, having its drain-source current path coupled between the supply voltage and saidcapacitor, for precharging said capacitor and having a gate;
- and
- a second boot-strap circuit having an output node operatively connected to the gate of said precharging transistor in said first boot-strap circuit, for driving the gate of said precharging transistor to a precharged voltage above the supply voltage when the input signal has a second logic level.
Dependencies are inferred from the claim text.