Tunable gain amplifier
First Claim
Patent Images
1. A circuit, comprising:
- a differential amplifier adapted to receive a pair of input signals at an input of a respective pair of input terminals and provide at a first output a differential output signal representing a gain of the difference between the pair of 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 pair of input signals and having a second output connected to the first output, 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.
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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.
6 Citations
18 Claims
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1. A circuit, comprising:
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a differential amplifier adapted to receive a pair of input signals at an input of a respective pair of input terminals and provide at a first output a differential output signal representing a gain of the difference between the pair of 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 pair of input signals and having a second output connected to the first output, 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A circuit, comprising:
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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, wherein the differential amplifier comprises a plurality of connecting elements alternately connectable between the pair of current sources, a first one of the plurality of connecting elements being adapted to, when connected between the pair of current sources, place the differential amplifier in a buffer mode, and a second one of the plurality of connecting elements being adapted to, when connected between the pair of current sources, place the differential amplifier in an equalizer mode. - View Dependent Claims (14, 15, 16)
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17. A signal processing method, comprising:
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providing a differential input signal at a differential input of a voltage-gain amplifier having a variable gain, the voltage-gain amplifier having; a first pair of transistors, each having a control electrode adapted to receive a respective input signal of the differential 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; providing a gain input to the voltage-gain amplifier to select a differential gain value of the voltage-gain amplifier from a plurality of available differential gain values; and selecting a mode of operation of the voltage-gain amplifier between a buffer mode and an equalizer mode, wherein the selecting the mode of operation comprises alternately coupling the pair of current sources with a conductive path and a resistor-capacitor combination. - View Dependent Claims (18)
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Specification