| 摘要 |
A method and apparatus are provided for calibrating a ladder circuit. The apparatus includes: a logic unit for receiving a first logical signal, a second logical signal, and N control bits and for outputting N alternative control bits and an additional control bit, where N is an integer greater than 1; a core circuit for receiving the N alternative control bits, the additional control bit, and a tuning word, and for outputting an output signal, wherein the core circuit comprises N−1 series elements, N shunt elements with a connectivity controlled by the N alternative control bits, respectively, and a termination element with a connectivity controlled by the additional control bit; and a calibration circuit for receiving the first logical signal, the second logical signal, and the output signal and for outputting the tuning word. When the first logical signal is 0, the apparatus operates in a normal mode and the output signal follows the N control bits; when the first logical signal is 1, the apparatus operates in a calibration mode and the output signal follows the second logical signal. When the apparatus operates in the calibration mode, the tuning word is adjusted in a closed loop manner so as to make the output signal substantially the same regardless of a value of the second logical signal.
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