Automatic-bias amplifier circuit
First Claim
1. An automatic-bias amplifier circuit comprising:
- an amplifier comprising an input, an output, and a signal path between and including the input and output of the amplifier, wherein the amplifier is coupled to a fixed-level DC voltage source; and
a feedback loop coupled between the signal path and a bias input of the amplifier, wherein the feedback loop comprises a power detector and a bias circuit, wherein the power detector comprises an input coupled to the signal path, and is operable for sampling a first signal on the signal path and for outputting to the feedback loop an analog voltage signal reflective of the power of the first signal, and wherein the bias circuit is on the feedback loop between the power detector and the bias input of the amplifier, and causes the amplifier to draw a quiescent current, from the fixed-level DC voltage source, that varies proportionally with the analog voltage signal.
1 Assignment
0 Petitions
Accused Products
Abstract
An automatic-bias amplifier circuit includes an amplifier having an input, an output, and a signal path between the input and output. A power detector is coupled for sampling the power of a signal passed on the signal path. The point of coupling may be the output and/or at one or more internal nodes of the amplifier. The power detector outputs an analog voltage signal reflective of the power of the signal to a bias circuit. The bias circuit causes the amplifier to draw a quiescent current, from a fixed level DC power supply, that varies in proportion to the analog voltage signal. Accordingly, the power consumption of the amplifier is optimized for all output power levels of the amplifier, while maintaining a desired degree of linearity. The automatic-bias amplifier circuit may be used in a wireless radio frequency communications device, e.g., a cellular phone.
95 Citations
36 Claims
-
1. An automatic-bias amplifier circuit comprising:
-
an amplifier comprising an input, an output, and a signal path between and including the input and output of the amplifier, wherein the amplifier is coupled to a fixed-level DC voltage source; and
a feedback loop coupled between the signal path and a bias input of the amplifier, wherein the feedback loop comprises a power detector and a bias circuit, wherein the power detector comprises an input coupled to the signal path, and is operable for sampling a first signal on the signal path and for outputting to the feedback loop an analog voltage signal reflective of the power of the first signal, and wherein the bias circuit is on the feedback loop between the power detector and the bias input of the amplifier, and causes the amplifier to draw a quiescent current, from the fixed-level DC voltage source, that varies proportionally with the analog voltage signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. An automatic-bias amplifier circuit comprising:
-
an amplifier comprising an input, an output, and a signal path between and including the input and output of the amplifier;
a power detector comprising an input coupled to the signal path, said power detector being operable for sampling a first signal on the signal path and for outputting an analog voltage signal reflective of the power of the first signal; and
a bias circuit coupled between the amplifier and the power detector, wherein the bias circuit generates an analog current that varies proportionally with analog voltage signal, and mirrors the analog current into the amplifier as at least part of a quiescent current of the amplifier. - View Dependent Claims (17, 18, 19)
-
-
20. A wireless communication device comprising:
-
a baseband processor, an antenna, and a signal path between the baseband processor and the antenna;
an amplifier comprising an input on the signal path, and an output on the signal path coupled to the antenna;
a fixed-level DC voltage source coupled to the amplifier;
a power detector operable for sampling an RF signal on the signal path and for outputting an analog voltage signal reflective of the power of the RF signal; and
a bias circuit coupled between the power detector and a bias input of the amplifier, wherein the bias circuit causes the amplifier to draw a quiescent current, from the fixed-level DC voltage source, that varies proportionally with the analog voltage signal. - View Dependent Claims (21, 22, 23, 24, 25, 26)
-
-
27. A wireless communication device comprising:
-
a baseband processor, an antenna, and a signal path between the baseband processor and the antenna;
an amplifier comprising an input on the signal path, and an output on the signal path coupled to the antenna;
a power detector operable for sampling an RF signal on the signal path and for outputting an analog voltage signal reflective of the power of the RF signal; and
a bias circuit coupled between the power detector and a bias input of the amplifier, wherein the bias circuit controls a quiescent current of the amplifier based on the analog voltage signal.
-
-
28. A method comprising:
-
providing an amplifier on a signal path, said amplifier having an input on the signal path and an output on the signal path;
receiving a first signal on the signal path at the input of the amplifier, amplifying the first signal in the amplifier, and outputting the amplified first signal at the output of the amplifier;
detecting a power level of the first signal on the signal path at a sampling point of the amplifier selected from a group consisting of the output of the amplifier and an interior node of the amplifier, said interior node being between, but exclusive of, the input and the output of the amplifier;
generating an analog voltage signal reflective of the detected power level of the first signal; and
drawing a quiescent current in the amplifier from a fixed level DC power supply, said quiescent current varying proportionally with the analog voltage signal. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36)
-
Specification