Variable gain amplifier circuit, controller of main amplifier and associated control method
First Claim
1. A variable gain amplifier circuit, comprising:
- a main amplifier, for amplifying an input signal to generate an output signal;
a current sensing circuit, coupled to the main amplifier, for providing a sensed current related to a current flowing through the main amplifier;
a variable loading, coupled to the current sensing circuit via a node, wherein the sensed current flows through the node and the variable loading to provide a loading voltage; and
a control amplifier, coupled to the node and the main amplifier, for receiving a control voltage and the loading voltage to generate an adjustment signal to control a gain of the main amplifier;
wherein a resistance of the variable loading has a nonlinear relationship with the control voltage; and
the variable loading comprises a plurality of circuit cells, and each of the circuit cells provides a specific current to the node, and a combination of the specific currents provided by the circuit cells is comprised of the sensed current flowing through the node and the variable loading.
1 Assignment
0 Petitions
Accused Products
Abstract
A variable gain amplifier circuit comprises a main amplifier, a current sensing circuit, a variable loading and a control amplifier. The main amplifier is configured for amplifying an input signal to generate an output signal. The current sensing circuit is coupled to the main amplifier, and is configured for generating a sensed current related to a current flowing through the main amplifier. The variable loading is coupled to the current mirror via a node, wherein the sensed current flows through the node and the variable loading. The control amplifier is coupled to the node and the main amplifier, and is configured for receiving a control voltage and a voltage of the node to generate an adjustment signal to control a gain of the main amplifier, wherein a resistance of the variable loading has a nonlinear relationship with the control voltage.
-
Citations
22 Claims
-
1. A variable gain amplifier circuit, comprising:
-
a main amplifier, for amplifying an input signal to generate an output signal; a current sensing circuit, coupled to the main amplifier, for providing a sensed current related to a current flowing through the main amplifier; a variable loading, coupled to the current sensing circuit via a node, wherein the sensed current flows through the node and the variable loading to provide a loading voltage; and a control amplifier, coupled to the node and the main amplifier, for receiving a control voltage and the loading voltage to generate an adjustment signal to control a gain of the main amplifier; wherein a resistance of the variable loading has a nonlinear relationship with the control voltage; and
the variable loading comprises a plurality of circuit cells, and each of the circuit cells provides a specific current to the node, and a combination of the specific currents provided by the circuit cells is comprised of the sensed current flowing through the node and the variable loading. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 20)
-
-
9. A controller of a main amplifier, comprising:
-
a current sensing circuit, for generating a sensed current related to a current flowing through the main amplifier; a variable loading, coupled to the current mirror via a node, wherein the sensed current flows through the node and the variable loading; and a control amplifier, coupled to the node, for receiving a control voltage and a loading voltage of the node to generate an adjustment signal to control a gain of the main amplifier; wherein a resistance of the variable loading has a nonlinear relationship with the control voltage; and
the variable loading comprises a plurality of circuit cells, and each of the circuit cells provides a specific current to the node, and a combination of the specific currents provided by the circuit cells is comprised of the sensed current flowing through the node and the variable loading. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 21)
-
-
17. A method for controlling a main amplifier, comprising:
-
generating a sensed current related to a current flowing through the main amplifier; providing a variable loading for receiving the sensed current at a node, wherein the variable loading comprises a plurality of circuit cells, and each of the circuit cells provides a specific current to the node, and a combination of the specific currents provided by the circuit cells is comprised of the sensed current flowing through the node and the variable loading; and generating an adjustment signal according to a control voltage and a loading voltage of the node to control a gain of the main amplifier; wherein a resistance of the variable loading has a nonlinear relationship with the control voltage. - View Dependent Claims (18, 19, 22)
-
Specification