Distributed transmitter output power control circuit and method for a radio telephone

• US 5,752,172 A
• Filed: 08/16/1996
• Issued: 05/12/1998
• Est. Priority Date: 08/16/1996
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Matero, Jorma
• Primary Examiner(s): Au, Amelia
• Application Number:
  US08/696,582
• Time in Patent Office: 634 Days
• Field of Search: 455/127, 455/126, 455/571, 455/575, 455/522, 375/297
• US Class Current: 455/127.3
• CPC Class Codes: H01Q 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them
• 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 1/04 Circuits

Abstract

Disclosed is a transmitter circuit (14) for use in radio telephone (10), the transmitter circuit including a power amplifier (17D) having an output coupled to an antenna (12) for transmitting an amplified modulated RF signal; a variable gain driver amplifier (17C) having an output coupled to an input of the power amplifier and an input coupled to an output of a modulator (14A), the variable gain driver amplifier being required to output the modulated RF signal within a predetermined dynamic power range having a maximum value; and at least one programmable gain amplifier (PGA1, PGA2) coupled in series between the output of the modulator and the input of the variable gain driver amplifier. The at least one programmable gain amplifier has a dynamic range selected for reducing the dynamic range requirement of the variable gain driver amplifier to be less than the predetermined dynamic power range. For example, the maximum predetermined dynamic range value is in excess of 60 dB, and a maximum dynamic range value of the variable gain driver amplifier is less than 50 dB (e.g., 40 dB to 44 dB).

Claims

1. A transmitter circuit for use in a radio telephone, comprising:

a power amplifier having an output coupled to an antenna for transmitting an amplified modulated RF signal;

a variable gain driver amplifier having an output coupled to an input of said power amplifier and an input coupled to an output of a modulator, said variable gain driver amplifier being required to output the modulated RF signal within a predetermined dynamic power range having a maximum value; and

at least one programmable gain amplifier coupled in series between said output of said modulator and said input of said variable gain driver amplifier, wherein said at least one programmable gain amplifier has a dynamic range selected for reducing the dynamic range requirement of said variable gain driver amplifier to be less than the maximum value of the predetermined dynamic power range.

2. A transmitter circuit as set forth in claim 1, wherein said maximum value of said predetermined dynamic range is in excess of 60 dB, and wherein a maximum value of said dynamic power range of said variable gain driver amplifier is less than 50 dB.

3. A transmitter circuit for use in a radio telephone, comprising:

a power amplifier having an output coupled to an antenna for transmitting an amplified modulated RF signal;

a variable gain driver amplifier having an output coupled to an input of said power amplifier and an input coupled to an output of a modulator, said variable gain driver amplifier being required to output the modulated RF signal within a predetermined dynamic power range having a maximum value; and

first and second programmable gain amplifiers coupled in series between said output of said modulator and said input of said variable gain driver amplifier, said first programmable gain amplifier having a first dynamic range that is adjustable in n steps, said second programmable gain amplifier having a second dynamic range that is adjustable in m steps, and wherein n is greater than m.

4. A transmitter circuit as set forth in claim 3, wherein n is equal to 12, and wherein m is equal to 3.

5. A transmitter circuit as set forth in claim 3, wherein each of the n steps is equal to 1 dB, and wherein each of the m steps is equal 12 dB.

6. A transmitter circuit as set forth in claim 3, wherein said first and second programmable gain amplifiers have a cumulative dynamic range selected for reducing the dynamic range requirement of said variable gain driver amplifier to be less than the maximum value of the predetermined dynamic power range.

7. A transmitter circuit as set forth in claim 6, wherein said maximum value of said predetermined dynamic range is in excess of 60 dB, and wherein a maximum value of said dynamic range of said variable gain driver amplifier is less than 50 dB.

8. A mobile station having an antenna coupled to an input of a receiver and to an output of a transmitter, a modulator having an output coupled to an input of said transmitter for providing a modulated RF signal to said transmitter, and a controller, said transmitter comprising:

a power control loop comprised of a power amplifier having an input coupled to an output of a variable gain driver amplifier, said variable gain amplifier having a control input for receiving a transmitter power control signal, a power sensor and detector coupled to an output of said power amplifier, and a circuit for comparing a maximum transmitted power control signal to an output of the detector for limiting a value of control signal applied to said variable gain driver amplifier; and

at least one programmable gain amplifier having an input coupled to said modulator output and an output coupled to an input of said variable gain driver amplifier, said at least one programmable gain amplifier having a dynamic range that is wide enough to compensate for variations in gain that are caused by component tolerances in at least said modulator and said power control loop.

9. A mobile station as set forth in claim 8, wherein said transmitter is comprised of first and second programmable gain amplifiers coupled in series between said output of said modulator and said input of said variable gain driver amplifier, said first programmable gain amplifier having a first dynamic range that is adjustable in n steps, said second programmable gain amplifier having a second dynamic range that is adjustable in m steps, and wherein n is greater than m.

10. A mobile station as set forth in claim in claim 9, wherein n is equal to 12, and wherein m is equal to 3.

11. A mobile station as set forth in claim 9, wherein each of the n steps is equal to 1 dB, and wherein each of the m steps is equal 12 dB.

12. A mobile station as set forth in claim 9, wherein said first and second programmable gain amplifiers have a cumulative dynamic range selected for reducing a dynamic range requirement of said variable gain driver amplifier to be less than a predetermined maximum dynamic power range.

13. A mobile station as set forth in claim 12, wherein said predetermined maximum dynamic range is in excess of 60 dB, and wherein a maximum value of said dynamic range of said variable gain driver amplifier is less than 50 dB.

14. A method of calibrating a transmitter circuit in a radio telephone, comprising the steps of:

providing the transmitter circuit so as to include a power amplifier having an output coupled to an antenna, a variable gain driver amplifier coupled to an input of the power amplifier, and at least one programmable gain amplifier coupled between an output of a modulator and an input of the variable gain driver amplifier;

setting a gain of the variable gain driver amplifier to a maximum level;

setting a gain of the at least one programmable gain amplifier to a mid-level;

measuring a power level at the output of the power amplifier;

comparing the measured power level to an expected power level; and

adjusting the gain of the at least one programmable gain amplifier to an adjusted value so as to bring the measured power level into agreement with the expected power level.

15. A method as set forth in claim 14, and further comprising a step of storing, in the radio telephone, an indication of the adjusted value for subsequent use during the operation of the radio telephone.