Capacitive feedforward circuit, system, and method to reduce buffer propagation delay

Abstract

A buffer circuit, system, and method are provided. The buffer circuit includes a control circuit coupled to an output of the buffer, or possibly to an output of the first stage of a buffer. A pre-charge circuit is also provided coupled to bias an input of the control circuit to a voltage value approximately near a threshold voltage of the control circuit. The pre-charge bias amount is slightly less than the amount needed to place the control circuit in a high current conduction state. A coupling circuit is thereafter used and adapted to couple an input voltage applied to the buffer circuit to the input of the control circuit. This causes the control circuit to enter the high current conduction state. Depending on the input impedance of the coupling circuit, by pre-charging the coupling circuit input, less time is needed to cause the coupling circuit to enter and thereafter leave a high current conduction state. Therefore, by pre-charging the coupling circuit, output transitions from the buffer circuit can be accelerated and propagation delay reduced. The pre-charge circuit and the control circuit operate on one or more stages of a single or multi-stage buffer, operate on single-ended or differential/complementary input/output, and operate to speed up either the rising, falling, or both edges transitions at the output of the buffer.