Linear buffer
AssigneeBroadcom Corporation
InventorsTodd L. Brooks, Anilkumar V. Tammineedi
Life of this patent
Estimating the term…
Abstract
A source-follower transistor based buffer provides high linearity. A replica transistor is used to generate a replica voltage substantially equal to the output voltage of the buffer. The replica voltage is level shifted by a level shift circuit and applied at the drain of the source-follower transistor to improve the linearity of the buffer. The buffer may be used in conjunction with a switched-capacitor sampling circuit. A damping circuit may be used to reduce charge glitches due to sampling. The damping circuit may be a low pass filter. The buffer may be used in an interface circuit that produces an output signal from an input signal and controls the level of the output signal.
Claims18
An interface circuit for producing an output signal from an input signal and a reference signal, wherein the output signal has an output direct current (dc) voltage level that is substantially equal to a dc voltage level of the reference signal, the interface circuit comprising:
- a level translation module adapted to generate an input control signal from the reference signal;
- a level adjustment module adapted to produce an adjusted buffer input signal from the input signal, wherein the adjusted buffer input signal has a dc voltage level that is substantially equal to a dc voltage level of the input level control signal, and
- a buffer adapted to generate the output signal from the adjusted buffer input signal;
- wherein said level translation module comprises
- a replica buffer adapted to generate a replica buffer output signal from the input level control signal;
- and
- a difference amplifier having a positive input terminal adapted to receive the reference signal, a negative input terminal adapted to receive the replica buffer output signal, and an output terminal adapted to generate the input level control signal.
An apparatus that provides an output signal based on an input signal and a reference signal, comprising:
- a level translation module to generate an input level control signal having a first dc level that is based on the reference signal;
- a level adjustment module to provide an adjusted buffer input signal based on the input signal and the input level control signal, wherein the adjusted buffer input signal has a dc level that is substantially equal to the first dc level;
- and
- a buffer to provide the output signal based on the adjusted buffer input signal;
- wherein the level translation module includes
- a replica buffer to provide a replica buffer output signal based on the input level control signal;
- and
- a difference amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein the difference amplifier is configured to provide the input level control signal at the output terminal based on the reference signal at the positive input terminal and the replica buffer output signal at the negative input terminal.
Dependencies are inferred from the claim text.