Tunable gain amplifier
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsShu-Chun Yang, Wei Chih Chen, Yu-Nan Shih
Life of this patent
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Abstract
A amplifier circuit in some embodiment includes a differential amplifier have a pair of current sources. Each of the current sources includes two or more current-generating transistors and respective switching transistors, which can be turned on and off by a gain input code to tune the gain of the amplifier. A common-mode controller includes a similar pair of current sources as the differential amplifier. The common mode controller receives a common-mode signal of the input signal and a common-mode gain input code, and maintains the common-mode gain of the amplifier circuit when the differential gain changes. The amplifier circuit is switchable between a buffer mode and an equalizer mode.
Claims20
A circuit, comprising:
- a differential amplifier adapted to receive a pair of input signals at a respective pair of input terminals and provide at an output terminal an output representing a gain of the difference between the two input signals, the differential amplifier having a gain input terminal and being adapted to set the gain in response to a gain input at the gain input terminal;
- and
- a common-mode controller adapted to receive a signal corresponding to a common-mode signal of the input signals and having an output connected to the output terminal, the common-mode controller having a common-mode gain input terminal and being adapted to set a common-mode gain of the circuit in response to a common-mode gain input at the common-mode gain input terminal.
A circuit, comprising:
- a differential amplifier, comprising:
- a first pair of transistors, each having a control electrode adapted to receive a respective input signal;
- a first main electrode adapted to provide an output signal;
- and a second main electrode;
- a pair of loads, each connected between the first main electrode of a respective one of the pair of transistors and a first voltage supply;
- and
- a pair of current sources, each connected between the second main electrode of a respective one of the pair of transistors and a second voltage supply, and adapted to output a current of a variable magnitude,
- the differential amplifier being switchable between a buffer mode and an equalizer mode.
A signal processing method, comprising:
- providing an input signal at a differential input of a variable-gain amplifier;
- providing a gain input to the amplifier to select a differential gain value of the amplifier from a plurality of available differential gain values;
- and
- selecting a mode of signal processing of the amplifier from a plurality of available modes.
Dependencies are inferred from the claim text.