Variable gain amplifier
AssigneeRealtek Semiconductor Corp.
InventorsWen-Chi Wang, Chao-Cheng Lee, Jui-Cheng Huang, Jui-Yuan Tsai
Life of this patent
Estimating the term…
Abstract
The variable gain amplifier of the present invention includes at least an operation amplifier. By choosing one of output stages, a feedback resistor is selected and the gain of the variable gain amplifier is decided according to the resistance of the selected feedback resistor, as desired. By adjusting the gain of the variable gain amplifier, the received signals can be amplified or attenuated in accordance with design requirement. The variable gain amplifier can include a two-stage architecture, in which a first stage is used for coarse gain adjustment and a second stage is used for fine gain adjustment. The gain of the two-stage variable gain amplifier can be easily adjusted to a desired value.
Claims17
A variable gain amplifier comprising:
- a first stage operational amplification unit for providing a first gain, comprising:
- a first input resistor coupled to an input signal;
- an operational amplifier comprising:
- a pre-drive stage coupled to the input resistor;
- and
- a plurality of output stages, each output stage coupled to the pre-drive stage;
- and
- a plurality of first feedback resistors, each first feedback resistor being coupled to the pre-drive stage by one end thereof and coupled to one of the plurality of output stages by another end thereof;
- and
- a second stage operational amplification unit coupled to the first stage operational amplification unit, for providing a second gain;
- wherein a first feedback loop is formed by one of the output stages chosen by a first control signal and the first feedback resistor corresponding to the chosen output stage, and a gain of the variable gain amplifier corresponds to the first and the second gain.
A variable gain amplifier comprising:
- a pre-drive stage comprising a first input node for receiving a input signal;
- a plurality of output stages, wherein one of the output stages is selected by a control signal to couple to the pre-drive stage;
- and
- a plurality of feedback impedance, each of the feedback impedances being coupled between the pre-drive stage and one of the output stages;
- wherein the pre-drive stage comprising a first output node and a second output node, each of the output stages comprising a first input node, a second input node, and an output node, and each of the feedback impedance is coupled between the first input node of the pre-drive stage and the output node of the corresponding output stage;
- and
- wherein the gain of the variable gain amplifier is determined according to one of the feedback impedances coupled to the selected output stages and the pre-drive stage.
A variable gain amplifier comprising:
- an input resistor;
- a pre-drive stage coupled to the input resistor;
- a plurality of feedback resistors, each feedback resistor coupled to the pre-drive stage at one end;
- a plurality of output stages, each output stage coupled to one of the feedback resistors at another end thereof, forming a plurality of feedback loops;
- and
- a plurality of switches, coupled to one of the feedback loops at one end, and the switches coupled to a later stage at another end;
- wherein one of the feedback loops is chosen by one of the switches.
A variable gain amplifier comprising:
- a pre-drive stage comprising a first input node for receiving an input signal;
- a plurality of feedback elements with impedance are coupled to the pre-drive stage at one end;
- a plurality of output stages, each output stage coupled to one of the feedback elements at another end thereof, forming a plurality of feedback loops;
- and
- a plurality of switches, coupled to one of the feedback loops at one end, and the switches coupled to a later stage at another end;
- wherein the gain of the variable gain amplifier is determined according to the on and off state of the switches.
Dependencies are inferred from the claim text.