Integrated RF power sensor that compensates for bias changes
First Claim
1. A system for sensing RF amplifier output power and controlling a bias circuit comprising:
- a RF amplifier transistor configured to receive and amplify a RF signal;
a first sampling transistor configured to receive and amplify the RF signal wherein the first sampling transistor is physically smaller than the RF amplifier transistor such that the first sampling transistor is capable of producing a proportionally smaller amplified RF signal than that capable of being produced by the RF amplifier transistor for a RF input signal common to both the RF amplifier transistor and the first sampling transistor;
a second sampling transistor configured to receive and amplify a bias circuit signal;
a first current sensing circuit configured to receive a RF signal amplified by the first sampling transistor and generate a RF current proportional to a RF signal amplified by the RF amplifier transistor;
a second current sensing circuit configured to receive a bias circuit signal amplified by the second sampling transistor and generate a bias network current; and
a feedback configured to be responsive to the bias circuit current and generate the bias circuit signal.
7 Assignments
0 Petitions
Accused Products
Abstract
A system for controlling a bias circuit by sensing RF amplifier output power and compensating for a dominating quiescent bias current includes an amplifier transistor and two sampling transistors. The two sampling transistors are physically smaller than the amplifier transistor, and are preferably the same size. The first sampling transistor is configured to sample the same RF input signal that is amplified by the amplifier transistor. The second sampling transistor is configured to receive and amplify only a bias network signal. The bias network associated with the transistors includes a selection of components based upon operating parameters as well as actual physical sizes of the transistors. The selection of component values in association with transistor sizes is used to enable generation of a current sensing signal that is proportional to the power level of the RF output signal generated by the amplifier transistor. The bias current to the amplifier transistor is controlled by an operational amplifier that is fed with a reference voltage and the dc bias detected by the second small transistor.
-
Citations
33 Claims
-
1. A system for sensing RF amplifier output power and controlling a bias circuit comprising:
-
a RF amplifier transistor configured to receive and amplify a RF signal;
a first sampling transistor configured to receive and amplify the RF signal wherein the first sampling transistor is physically smaller than the RF amplifier transistor such that the first sampling transistor is capable of producing a proportionally smaller amplified RF signal than that capable of being produced by the RF amplifier transistor for a RF input signal common to both the RF amplifier transistor and the first sampling transistor;
a second sampling transistor configured to receive and amplify a bias circuit signal;
a first current sensing circuit configured to receive a RF signal amplified by the first sampling transistor and generate a RF current proportional to a RF signal amplified by the RF amplifier transistor;
a second current sensing circuit configured to receive a bias circuit signal amplified by the second sampling transistor and generate a bias network current; and
a feedback configured to be responsive to the bias circuit current and generate the bias circuit signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A system for sensing RF amplifier output power and controlling a bias circuit comprising:
-
a RF amplifier having an amplifier transistor and further having a first RF signal input port and a first RF signal output port;
a first sampling amplifier having a first sampling transistor, a second RF signal input port coupled to the first RF signal input port, and a second RF signal output port wherein the first sampling transistor is physically smaller than the amplifier transistor;
a second sampling amplifier having a second amplifying transistor, a first bias circuit input port, and a first bias circuit output port;
a first current sensing network having a third RF signal input port and a first voltage input port, wherein the third RF signal input port is coupled to the second RF signal output port;
a second current sensing network having a second bias circuit input port and a second voltage input port, wherein the second bias circuit input port is coupled to the first bias circuit output port; and
a feedback configured to be responsive to the second current sensing network and generate a bias circuit signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
-
-
26. A system for sensing RF amplifier output power and controlling a bias circuit comprising:
-
amplifying means for amplifying a RF input signal and generating a RF output signal therefrom;
first sampling means for sampling the RF input signal that is associated with the amplifying means and generating a sampled RF signal therefrom;
second sampling means for sampling a bias circuit signal and generating a sampled bias circuit signal therefrom;
first sensing means for sensing the sampled RF signal and generating a current sensing signal therefrom proportional to a power amplitude associated with the RF output signal;
second sensing means for sensing the sampled bias circuit signal and generating a bias sensing signal therefrom; and
feedback means for responding to the bias sensing signal and generating the bias circuit signal. - View Dependent Claims (27, 28, 29, 30, 31)
-
-
32. A method for sensing RF signal power amplitude and controlling a bias circuit, the method comprising the steps of:
-
(a) providing a RF signal amplifier comprising a first transistor having a first predetermined size;
(b) providing a first sampling amplifier comprising a second transistor having a second predetermined size that is smaller than the first predetermined size;
(c) providing a second sampling amplifier comprising a third transistor having a third predetermined size that is smaller than the first predetermined size;
(d) amplifying a RF input signal to produce a first RF output signal;
(e) sampling the RF input signal to produce a second RF output signal proportional to the first RF output signal, wherein the proportion is associated with a ratio determined by the first and second predetermined sizes;
(f) sampling a bias circuit signal to produce a bias circuit output signal; and
(g) controlling a bias circuit by responding to the bias circuit output signal and generating the bias circuit signal.
-
-
33. A system for sensing RF amplifier output power comprising:
-
a RF amplifier transistor configured to receive and amplify a RF signal;
a first sampling transistor configured to receive and amplify the RF signal, wherein the first sampling transistor is physically smaller than the RF amplifier transistor such that the first sampling transistor is capable of producing a proportionally smaller amplified RF signal than that capable of being produced by the RF amplifier transistor for a RF input signal common to both the RF amplifier transistor and the first sampling transistor;
a second sampling transistor configured to receive and amplify a bias circuit signal, wherein the second sampling transistor is physically smaller than the RF amplifier transistor;
a first current sensing circuit configured to receive a RF signal amplified by the first sampling transistor and generate a current proportional to a power amplitude associated with the RF signal amplified by the RF amplifier transistor;
a second current sensing circuit configured to receive a bias circuit signal amplified by the second sampling transistor and generate a sampled bias circuit current;
a feedback configured to be responsive to the sampled bias circuit current and generate the bias circuit signal to establish a quiescent operating point for the RF amplifier transistor, the first sampling transistor, and the second sampling transistor;
a first bias resistor associated with the RF amplifier transistor; and
a second bias resistor associated with the first sampling transistor; and
a third bias resistor associated with the second sampling transistor;
wherein a ratio of resistor values between the first bias resistor and the second bias resistor is substantially equal to a ratio of physical sizes between the first sampling transistor and the RF amplifier transistor and wherein a ratio of resistor values between the first bias resistor and the third bias resistor is substantially equal to a ratio of physical sizes between the second sampling transistor and the RF amplifier transistor.
-
Specification