DC CURRENT BASED ON CHIP RF POWER DETECTION SCHEME FOR A POWER AMPLIFIER

• US 20100075724A1
• Filed: 09/22/2008
• Published: 03/25/2010
• Est. Priority Date: 09/22/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Cohen, David, SIVADAS, APU, Rajendran, Gireesh, Lachhwani, Ashish
• Granted Patent: US 8,326,371 B2
• Time in Patent Office: Days
• US Class Current: 455/571
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control

Abstract

A method, system, and apparatus of a DC current based on chip RF power detection scheme for a power amplifier are disclosed. In one embodiment, a method includes generating a scaled current from an other current associated with power amplifier, transforming the scaled current (e.g., the scaled current may be scaled to the other current value) into a digital signal and using the digital signal to set a radio frequency power value of an antenna of the antenna module. The method may include transforming the scaled current into a voltage signal. The method may also include transforming the voltage signal into the digital signal. The method may also include generating a current mirror from a low dropout regulator.

Claims

1. A method comprising:

generating a scaled current from an other current associated with an antenna module;

transforming the scaled current into a digital signal; and

using the digital signal to set a radio frequency power value of an antenna of the antenna module.

2. The method of claim 1:

wherein the scaled current is generated by a current mirror circuit coupled with a low dropout regulator (LDO) coupled with a power amplifier (PA) used to drive the antenna module;

wherein the scaled current is scaled to the other current value;

further comprising transforming the scaled current into a voltage signal; and

further comprising transforming the voltage signal into the digital signal.

3. The method of claim 2:

wherein the current is scaled to a value of 50 to 500 times less than the other current; and

wherein the other current is a direct current (DC) drain current of the power amplifier.

4. The method of claim 2:

wherein the current mirror circuit is a transistor coupled to an other transistor of the LDO; and

wherein a width value and a length value of the transistor are scaled to an other width value and an other length value of the other transistor.

5. The method of claim 4:

wherein the PA is at least one of a differential PA OR a single-ended PA;

wherein the current mirror circuit is comprised of a plurality of transistors coupled to the other transistor; and

wherein the plurality of transistors are programmable according to a transistor control module.

6. The method of claim 1:

further comprising using an analog to digital converter (ADC) module to convert the scaled current to the digital signal; and

further comprising setting the value of the digital signal that is an output of the ADC module according to a specified relation equation that relates a radio frequency power value of the antenna module with a value of the other current consumed by the power amplifier (PA).

7. The method of claim 6:

wherein the ADC module is located in a receiver circuit of a transceiver circuit associated with the antenna module; and

wherein the transceiver circuit is based on time division multiplexing (TDM).

8. The method of claim 6 wherein the transceiver circuit includes a frequency division multiplexer.

9. The method of claim 8:

further comprising injecting the current through an IF amplifier in order to transform the current into the voltage signal; and

wherein the specified relation equation is P_RF=a(I_DC−

I₀)²+b(I_DC−

I₀)+c wherein a, b and c are constant gain parameters, I₀ is an offset correction, and I_DC is the value of the other current.

10. The method of claim 9 wherein the IF amplifier includes a resistor with a specified value through which the scaled current is injected into the ADC module.

11. The method of claim 10 further comprising configuring an NMOS current mirror to sink the scaled current.

12. A system comprising:

a power amplifier (PA) module to provide a drain current and wherein the PA is associated with an antenna;

a sense module to generate a mirror current proportional to the drain current with a current mirror; and

a converter module to convert the mirror current into a digital signal used to set a radio frequency power of the antenna.

13. The system of claim 12 further comprising a digital base banding (DBB) module to use the digital signal to set the radio frequency power of an antenna module in real time.

14. The system of claim 13:

wherein the converter module is an existing analog to digital converter (ADC) of a receiver circuit of a transceiver associated with the antenna module; and

wherein the transceiver is based on time division multiplexing.

15. The system of claim 12:

wherein a low dropout regulator (LDO) pass transistor provides the drain current; and

wherein the current mirror is coupled with a transistor of the LDO pass transistor.

16. The system of claim 12 wherein the PA module is selected from a group comprising of a substantially class-A PA, a class A-B PA, a class-B PA, a class-C PA, a deep class-C PA and a switch-typed PA.

17. The system of claim 12:

wherein the converter module is a resistor coupled to an Intermediate Frequency (IF) amplifier and an analog to digital converter (ADC); and

wherein to the IF amplifier is used to convert the mirror current to a voltage signal and to terminate the resistor.

18. The system of claim 17:

wherein the converter module contains at least one n-channel MOSFET current mirror to sink the mirror current; and

wherein the sense module uses a plurality of programmable current mirrors to generate the mirror current.

19. A method comprising:

configuring a power amplifier of an antenna circuit with a current mirror to generate a mirror current proportionally related to a drain current of the power amplifier;

configuring an analog to digital converter circuit to convert the mirror current to a digital signal proportionally related to the drain current of the power amplifier; and

configuring a control module to use the digital signal to set transmitted radio frequency (RF) power value of an antenna in real time according to a relationship between the digital signal and the drain current.

20. The method of claim 19:

further comprising configuring an analog to digital converter of a transceiver associated with the antenna to convert the mirror current to a digital signal;

further comprising creating an index to relate the antenna transmitted RF power value to the drain current with an equation P_RF=a(I_DC−

I₀)²+b(I_DC−

I₀)+c;

wherein a, b and c are constant gain parameters, I₀ is an offset correction, and I_DC is the value of an other current;

further comprising using the index to set the antenna transmitted RF power value of the antenna in real time according to the relationship between the digital signal and the drain current; and

wherein the current mirror is coupled to a final stage low dropout regulator (LDO) of the power amplifier.