Polar transmitter amplifier with variable output power

• US 20080003960A1
• Filed: 06/29/2006
• Published: 01/03/2008
• Est. Priority Date: 06/29/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Zolfaghari, Alireza
• Granted Patent: US 7,817,962 B2
• Time in Patent Office: Days
• US Class Current: 455/127.3
• CPC Class Codes: H03C 5/00 Amplitude modulation and angle modulation produced simultaneously or at will by the same modulating signal H03C7/00 takes precedence
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 1/0211 with control of the supply voltage or current
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 2200/111 the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
• CPC Class Codes: H03F 2200/321 Use of a microprocessor in an amplifier circuit or its control circuit
• CPC Class Codes: H03F 2200/324 An amplitude modulator or demodulator being used in the amplifier circuit
• CPC Class Codes: H03F 2200/333 A frequency modulator or demodulator being used in the amplifier circuit
• CPC Class Codes: H03F 2200/504 the supply voltage or current being continuously controlled by a controlling signal, e.g. the controlling signal of a transistor implemented as variable resistor in a supply path for, an IC-block showed amplifier
• CPC Class Codes: H03F 2200/541 Transformer coupled at the output of an amplifier
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 1/0483 Transmitters with multiple parallel paths
• CPC Class Codes: H04B 2001/0408 with power amplifiers

Abstract

Various embodiments are disclosed relating to wireless systems, and also relating to transmitter amplifiers, such as, for example, polar transmitter amplifiers with variable output power. According to an example embodiment, a circuit is provided including a plurality of selectable amplifier cells. Each amplifier cell may receive a phase or frequency modulated signal and an amplitude modulated signal. Each amplifier cell may output a signal based upon a combination of the received amplitude modulated signal and the received phase or frequency modulated signal if the amplifier cell is selected. The circuit may provide a variable output current or output power based upon the selection of one or more of the amplifier cells.

Claims

1. An apparatus comprising:

a multiplexer adapted to receive a plurality of phase or frequency modulated signals, each phase or frequency modulated signal provided on a different frequency band, the multiplexer adapted to select and output one of the received phase or frequency modulated signals; and

a multi-band driver circuit adapted to receive the selected phase or frequency modulated signal and an amplitude modulated signal, the multi-band driver circuit adapted to output onto a selected output a signal that combines the amplitude modulated signal and the selected phase or frequency modulated signal.

2. The apparatus of claim 1 and further comprising a plurality of power amplifiers, each of the power amplifiers adapted to operate in one of the frequency bands and being coupled to one of the outputs of the multi-band driver circuit.

3. The apparatus of claim 1 wherein the multi-band driver circuit comprises a plurality of selectable amplifier cells to provide a variable output current based upon the selection of one or more of the amplifier cells, each amplifier cell adapted to output a current that is based upon a combination of the received amplitude modulated signal and the selected phase or frequency modulated signal.

4. The apparatus of claim 3 wherein each amplifier cell comprises:

a first cascode pair of transistors coupled to a positive output of the amplifier cell;

a second cascode pair of transistors coupled to a negative output of the amplifier cell; and

a cascode current source.

5. The apparatus of claim 4 wherein the first and second cascode pairs each includes:

a first transistor coupled to one of the outputs of the amplifier cell, and adapted to receive an enabling bias voltage when the amplifier cell is enabled or selected; and

a second transistor coupled in series with the first transistor, the first transistor adapted to receive as an input either a positive or negative differential phase or frequency modulated signal.

6. The apparatus of claim 4 wherein the cascode current source comprises:

a first transistor coupled to the first and second cascode pairs, the first transistor adapted to receive an enabling bias voltage when the amplifier cell is enabled or selected; and

a second transistor coupled in series with the first transistor, the second transistor adapted to receive the amplitude modulated signal as an input.

7. The apparatus of claim 4 wherein each amplifier cell further comprises a current source coupled in parallel to the cascode current source.

8. The apparatus of claim 3 wherein the multi-band driver circuit further comprises a multi-band transformer coupled to an output of each of the amplifier cells.

9. The apparatus of claim 3 wherein the multi-band driver circuit further comprises:

a power control circuit adapted to receive a digital power control signal and to output one or more bias voltages to selectively enable one or more of the amplifier cells to vary or select an output current of the multi-band driver circuit based on the digital power control signal.

10. The apparatus of claim 1 wherein the apparatus further comprises:

a current D/A converter adapted to receive a digital amplitude signal and to provide an analog current based on the received digital amplitude signal, the current provided by the current D/A converter providing a first output voltage; and

an amplifier adapted to output the amplitude modulated signal to the multi-band driver circuit based on the first voltage and in accordance with a feedback loop to the amplifier.

14. The apparatus of claim 10 wherein the cascode current source comprises:

a first transistor coupled to the first and second cascode pairs, the first transistor adapted to receive an enabling bias voltage when the amplifier cell is enabled; and

a second transistor coupled in series with the first transistor, the second transistor adapted to receive the amplitude modulated signal at an input.

11. An apparatus comprising:

a plurality of selectable amplifier cells, each amplifier cell adapted to receive a phase or frequency modulated signal and an amplitude modulated signal, each amplifier cell being adapted to output a signal based upon a combination of the received amplitude modulated signal and the received phase or frequency modulated signal if the amplifier cell is selected, wherein the apparatus is adapted to provide a variable output current based upon the selection of one or more of the amplifier cells.

12. The apparatus of claim 11 wherein each amplifier cell comprises:

a first cascode pair of transistors coupled to a positive output of the amplifier cell;

a second cascode pair of transistors coupled to a negative output of the amplifier cell; and

a cascode current source.

13. The apparatus of claim 12 wherein the first and second cascode pairs each includes:

a first transistor coupled to one of the outputs of the amplifier cell, and adapted to receive an enabling bias voltage when the amplifier cell is enabled or selected; and

a second transistor coupled in series with the first transistor, the first transistor adapted to receive as an input either a positive or negative differential phase or frequency modulated signal.

15. The apparatus of claim 12 wherein each amplifier cell further comprises a current source coupled in parallel to the cascode current source.

16. The apparatus of claim 11 and further comprising a multi-band transformer coupled to an output of each of the amplifier cells.

17. The apparatus of claim 11 wherein each of the amplifier cells comprises a single balanced active mixer to combine phase and amplitude.

18. A method comprising:

receiving a phase or frequency modulated signal and an amplitude modulated signal at each of a plurality of selectable amplifier cells;

outputting, from each amplifier cell when selected or enabled, a signal based upon a combination of the received amplitude modulated signal and the received phase or frequency modulated signal; and

varying an output current or power by selecting or enabling one or more of the amplifier cells.

19. The method of claim 18 wherein the outputting comprises outputting, from each amplifier cell when selected or enabled, an amplitude and either phase or frequency modulated signal having a current that is proportional to the received amplitude signal and received phase or frequency modulated signal.

20. The method of claim 18 wherein the varying comprises:

receiving a power control signal;

selectively enabling one or more of the amplifier cells to vary an overall output power or output current based upon the received power control signal.