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AssigneeAnalog Devices, Inc.
InventorsBarrie Gilbert, Eberhard Brunner
Estimating the term…
A variable gain amplifier uses a differential attenuator to provide a differential input to which a differential input signal is applied. The differential attenuator is comprised of (N-1) .pi. attenuator stages, with each stage forming a pair of attenuator taps for providing an attenuated version of the differential input signal. The differential input forms a high-impedance input, which is essentially floating. Each pair of taps is coupled to the differential inputs of a respective gm stage. The differential outputs of the gm stages are coupled to the differential inputs of a main amplifier, which has a high open-loop gain. The transconductance of each gm stage is controlled by an interpolator which provides a bias current to each of the gm stages in a sequential manner as a gain control voltage is swept from its minimum to its maximum values. The combination of the attenuated input voltage, the varying transconductances produces a gain response that is linear-in-dB relative to the gain control voltage. The output of the main amp is fed back through a gain-setting resistor network through a fixed gm stage.
A variable-gain amplifier comprising:
A differential input, variable-gain amplifier comprising:
A differential input, variable-gain amplifier comprising:
Dependencies are inferred from the claim text.