High efficiency switched gain power amplifier

• US 6,208,202 B1
• Filed: 02/10/1999
• Issued: 03/27/2001
• Est. Priority Date: 09/22/1998
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Camarillo, Richard J., Hunzeker, Darin, Kaufman, Ralph E.
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): NGUYEN, KHANH V
• Application Number:
  US09/248,048
• Time in Patent Office: 776 Days
• Field of Search: 330/51, 330/53, 330/157, 330/306
• US Class Current: 330/51
• CPC Class Codes: H03F 2203/7231 the gated amplifier being switched on or off by putting into cascade or not, by choosing between amplifiers by one or more switch(es)
• CPC Class Codes: H03F 2203/7239 the gated amplifier being switched on or off by putting into parallel or not, by choosing between amplifiers and shunting lines by one or more switch(es)
• CPC Class Codes: H03F 3/602 Combinations of several amplifiers
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H03G 1/0088 using discontinuously variable devices, e.g. switch-operated

Abstract

A power amplifier circuit arrangement including a driver amplifier, a switch, an amplifier path having a band pass filter and a power amplifier, and a bypass path which bypasses the power amplifier when excess gain and output power are not needed. When an RF-analog signal from the driver amplifier is switched to the amplifier path, the signal is band-pass filtered and amplified. Then the signal is split into an in-phase and a quadrature signal. Either the in-phase or the quadrature signal is inverted and summed with the other of the in-phase or quadrature signal, and the summed signal is transmitted to an output port. When the RF-signal from the driver amplified is switched to the bypass path, the power amplifier is turned off and the bypass path directs the signal to the output of the power amplifier, which appears as a high impedance to the signal. The signal reflects off the power amplifier to the output port. This design preserves the benefits of bypassing the power amplifier by reducing the amount of switching loss introduced into the circuit.

Claims

1. A power amplifier circuit arrangement, comprising:

a driver amplifier for transmitting an analog signal;

a first switch for selectively switching the analog signal between a bypass path and an amplifier path, said amplifier path comprising;

a band-pass filter for filtering the analog signal and for producing a filtered signal;

a power amplifier for receiving the filtered signal and for producing an amplified signal;

a first hybrid circuit for splitting the amplified signal into an in-phase signal and a quadrature signal; and

a second hybrid circuit for inverting the in-phase signal to produce an inverted signal and for summing the inverted signal and the quadrature signal to produce a summed signal,

said bypass path connecting an output of said driver amplifier with an isolated port of said second hybrid circuit when said first switch switches the analog signal to said bypass path, whereby the analog signal transmitted from said driver amplifier will reflect off of said power amplifier and be routed to an output port.

2. The circuit arrangement of claim 1, further comprising:

a second switch positioned in said bypass path; and

a terminating resistor connected to a pole of said second switch,

said second switch selectively connecting the isolated port of said second hybrid circuit with either said first switch or said terminating resistor.

3. The circuit arrangement of claim 1, wherein the analog signal is a radio-frequency analog signal.

4. The power amplifier circuit arrangement of claim 1, wherein said first switch switches the analog signal to said bypass path when said power amplifier is turned off.

5. A power amplifier circuit arrangement, comprising:

a driver amplifier for transmitting an analog signal;

a first switch for selectively switching the analog signal between a bypass path and an amplifier path, said amplifier path comprising;

a band-pass filter for filtering the analog signal and for producing a filtered signal;

a power amplifier for receiving the filtered signal and for producing an amplified signal;

a first hybrid circuit for splitting the amplified signal into an in-phase signal and a quadrature signal; and

a second hybrid circuit for inverting the quadrature signal to produce an inverted signal and for summing the inverted signal and the in-phase signal to produce a summed signal,

said bypass path connecting an output of said driver amplifier with an isolated port of said second hybrid circuit when said first switch switches the analog signal to said bypass path, whereby the analog signal transmitted from said driver amplifier will reflect off of said power amplifier and be routed to an output port.

6. The circuit arrangement of claim 5, further comprising:

a second switch positioned in said bypass path; and

a terminating resistor connected to a pole of said second switch,

said second switch selectively connecting the isolated port of said second hybrid circuit with either said first switch or said terminating resistor.

7. The circuit arrangement of claim 5, wherein the analog signal is a radio-frequency analog signal.

8. The power amplifier circuit arrangement of claim 5, wherein said first switch switches the analog signal to said bypass path when said power amplifier is turned off.

9. A method for amplifying a signal in a circuit having a driver amplifier, an amplifier path comprising a first switch, a band-pass filter, a power amplifier, a first hybrid circuit and a second hybrid circuit, and a bypass path connecting an isolated port of the second hybrid circuit to the first switch, said method comprising:

(A) producing a driver signal from the driver amplifier;

(B) selectively switching the driver signal between the amplifier path and the bypass path using the first switch,

wherein when the driver signal is switched in said switching step to the amplifier path, said method further comprises the steps of;

(a) band-pass filtering the driver signal by the band-pass filter to produce a filtered signal;

(b) amplifying the filtered signal by the power amplifier to produce an amplified signal;

(c) splitting the amplified signal into an in-phase signal and a quadrature signal in the first hybrid circuit;

(d) inverting the in-phase signal to produce an inverted signal in the second hybrid circuit; and

(e) summing the inverted signal and the quadrature signal to produce a summed signal in the second hybrid circuit,

and wherein when the driver signal is switched in said switching step to the bypass path, said method further comprises the steps of;

(a) turning off the power amplifier;

(b) transmitting the driver signal to the isolated port of the second hybrid circuit;

(c) reflecting the driver signal off an output of the power amplifier to an output port.

10. The method of claim 9, wherein the circuit further comprises a second switch positioned in the bypass path, said method further comprising:

selectively switching the second switch between connecting the isolated port of the second hybrid circuit to a terminating resistor and connecting the isolated port of the second hybrid circuit to the first switch.

11. The method for amplifying a signal of claim 9, wherein the driver signal is a radio-frequency analog signal.

12. A power amplifier circuit arrangement, comprising:

a driver amplifier for transmitting an analog signal;

a first switch for switching the analog signal between a bypass path and an amplifier path, said amplifier path comprising;

a band pass filter which filters the analog signal to produce a filtered signal;

a first hybrid circuit for splitting the filtered signal into an in-phase signal and a quadrature signal;

a first power amplifier for amplifying the in-phase signal to produce a first amplified signal;

a second power amplifier for amplifying the quadrature signal to produce a second amplified signal; and

a second hybrid circuit for inverting the first amplified signal to produce an inverted signal and for summing the inverted signal and the second amplified signal,

said bypass path connecting an output of said driver amplifier and an isolated port of said second hybrid circuit when said first switch switches the analog signal to said bypass path.

13. The power amplifier circuit arrangement of claim 12, wherein the analog signal is a radio-frequency analog signal.

14. The power amplifier circuit arrangement of claim 12, wherein said switch switches to said bypass path when the power amplifier is turned off.

15. The circuit arrangement of claim 12 further comprising:

a second switch positioned in said bypass path; and

a terminating resistor connected to a pole of said second switch,

said second switch selectively connecting the isolated port of said second hybrid circuit with either said first switch or said terminating resistor.

16. The circuit arrangement of claim 12 further comprising:

a first shunt switch positioned between said first power amplifier and said second hybrid circuit; and

a second shunt switch positioned between said second power amplifier and said second hybrid circuit;

said first and second shunt switches being used to shunt the output of said first and second power amplifiers, respectively, when using said bypass path.

17. A power amplifier circuit arrangement, comprising:

a driver amplifier for transmitting an analog signal;

a first switch for switching the analog signal between a bypass path and an amplifier path, said amplifier path comprising;

a band pass filter which filters the analog signal to produce a filtered signal;

a first hybrid circuit for splitting the filtered signal into an in-phase signal and a quadrature signal;

a first power amplifier for amplifying the in-phase signal to produce a first amplified signal;

a second power amplifier for amplifying the quadrature signal to produce a second amplified signal; and

a second hybrid circuit for inverting the second amplified signal to produce an inverted signal and for summing the inverted signal and the first amplified signal,

said bypass path connecting an output of said driver amplifier and an isolated port of said second hybrid circuit when said first switch switches the analog signal to said bypass path.

18. The power amplifier circuit arrangement of claim 17, wherein the analog signal is a radio-frequency analog signal.

19. The power amplifier circuit arrangement of claim 17, wherein said switch switches to said bypass path when the power amplifier is turned off.

20. The circuit arrangement of claim 17 further comprising:

a second switch positioned in said bypass path; and

a terminating resistor connected to a pole of said second switch,

said second switch selectively connecting the isolated port of said second hybrid circuit with either said first switch or said terminating resistor.

21. The circuit arrangement of claim 17 further comprising:

a first shunt switch positioned between said first power amplifier and said second hybrid circuit; and

a second shunt switch positioned between said second power amplifier and said second hybrid circuit;

said first and second shunt switches being used to shunt the output of said first and second power amplifiers, respectively, when using said bypass path.

22. A method for amplifying a signal in a circuit having a driver amplifier, an amplifier path comprising a first switch, a band-pass filter, a first power amplifier, a second power amplifier, a first hybrid circuit and a second hybrid circuit, and a bypass path connecting an isolated port of the second hybrid circuit with the first switch, said method comprising:

(A) producing a driver signal from the driver amplifier;

(B) selectively switching the driver signal between the amplifier path and the bypass path using the first switch,

wherein when the driver signal is switched in said switching step to the amplifier path, said method further comprises;

(a) band-pass filtering the driver signal by the band-pass filter to produce a filtered signal;

(b) splitting the filtered signal in the first hybrid circuit into an in-phase signal and a quadrature signal;

(c) amplifying the in-phase signal by the first power amplifier to produce an amplified in-phase signal;

(d) amplifying the quadrature signal by the second power amplifier to produce an amplified quadrature signal;

(e) inverting the amplified in-phase signal in the second hybrid circuit to produce an inverted signal; and

(f) summing the inverted signal and the amplified quadrature signal in the second hybrid circuit to produce a summed signal,

and wherein when the driver signal is switched in said switching step to the bypass path, said method further comprises;

(a) turning off the first power amplifier and the second power amplifier;

(b) transmitting the driver signal to the isolated port of the second hybrid circuit;

(c) splitting the driver signal into an in-phase signal and a quadrature signal in the second hybrid circuit;

(d) reflecting the in-phase signal off of the first amplifier signal;

(e) reflecting the quadrature signal off of the second power amplifier;

(f) inverting the reflected in-phase signal in the second hybrid circuit to produce an inverted signal;

(g) summing the inverted signal and the quadrature signal in the second hybrid circuit to produce a summed signal; and

(h) outputting the summed signal to an output port.

23. The method for amplifying a signal of claim 22 wherein the driver signal is a radio-frequency analog signal.

24. The method of claim 22 wherein the circuit further comprises a second switch positioned in the bypass path, said method further comprising:

selectively switching the second switch between connecting the isolated port of the second hybrid circuit to a terminating resistor and connecting the isolated port of the second hybrid circuit to the first switch.

25. A method for amplifying a signal in a circuit having a driver amplifier, an amplifier path comprising a first switch, a band-pass filter, a first power amplifier, a second power amplifier, a first hybrid circuit and a second hybrid circuit, and a bypass path connecting an isolated port of the second hybrid circuit with the first switch, said method comprising:

(A) producing a driver signal from the driver amplifier;

(B) selectively switching the driver signal between the amplifier path and the bypass path using the first switch,

wherein when the driver signal is switched in said switching step to the amplifier path, said method further comprises;

(a) band-pass filtering the driver signal by the band-pass filter to produce a filtered signal;

(b) splitting the filtered signal in the first hybrid circuit into an in-phase signal and a quadrature signal;

(c) amplifying the in-phase signal by the first power amplifier to produce an amplified in-phase signal;

(d) amplifying the quadrature signal by the second power amplifier to produce an amplified quadrature signal;

(e) inverting the amplified quadrature signal in the second hybrid circuit to produce an inverted signal; and

(f) summing the inverted signal and the amplified in-phase signal in the second hybrid circuit to produce a summed signal,

and wherein when the driver signal is switched in said switching step to the bypass path, said method further comprises;

(a) turning off the first power amplifier and the second power amplifier;

(b) transmitting the driver signal to the isolated port of the second hybrid circuit;

(c) splitting the driver signal into an in-phase signal and a quadrature signal in the second hybrid circuit;

(d) reflecting the in-phase signal off of the first amplifier signal;

(e) reflecting the quadrature signal off of the second power amplifier;

(f) inverting the reflected quadrature signal in the second hybrid circuit to produce an inverted signal;

(g) summing the inverted signal and the in-phase in the second hybrid circuit to produce a summed signal; and

(h) outputting the summed signal to an output port.

26. The method for amplifying a signal of claim 25 wherein the driver signal is a radio-frequency analog signal.

27. The method of claim 25 wherein the circuit further comprises a second switch positioned in the bypass path, said method further comprising:

selectively switching the second switch between connecting the isolated port of the second hybrid circuit to a terminating resistor and connecting the isolated port of the second hybrid circuit to the first switch.

28. A mobile communication unit having a power supply, a digital processor, a receiving chain, a transmitting chain, a duplexer, an antenna, and user interfacing means, said mobile communication unit comprising:

a power amplifier circuit arrangement in said transmitting chain, said power amplifier circuit comprising;

a driver amplifier for transmitting an analog signal;

a first switch for selectively switching the analog signal between a bypass path and an amplifier path, said amplifier path comprising;

a band-pass filter for filtering the analog signal and for producing a filtered signal;

a power amplifier for receiving the filtered signal and for producing an amplified signal;

a first hybrid circuit for splitting the amplified signal into an in-phase signal and a quadrature signal; and

a second hybrid circuit for inverting the in-phase signal to produce an inverted signal and for summing the inverted signal and the quadrature signal to produce a summed signal,

said bypass path connecting an output of said driver amplifier with an isolated port of said second hybrid circuit when said first switch switches the analog signal to said bypass path, whereby the analog signal transmitted from said driver amplifier will reflect off of said power amplifier and be routed to an output port.

29. The mobile communication unit of claim 28, wherein said power amplifier circuit arrangement further comprises:

a second switch positioned in said bypass path; and

a terminating resistor connected to a pole of said second switch,

said second switch selectively connecting the isolated port of said second hybrid circuit with either said first switch or said terminating resistor.

30. The mobile communication unit of claim 28, wherein said first switch switches the analog signal to said bypass path when said power amplifier is turned off.

31. A mobile communication unit having a power supply, a digital processor, a receiving chain, a transmitting chain, a duplexer, an antenna, and user interfacing means, said mobile communication unit comprising:

a power amplifier circuit arrangement in said transmitting chain, said power amplifier circuit arrangement comprising;

a driver amplifier for transmitting an analog signal;

a first switch for switching the analog signal between a bypass path and an amplifier path, said amplifier path comprising;

a band pass filter which filters the analog signal to produce a filtered signal;

a first hybrid circuit for splitting the filtered signal into an in-phase signal and a quadrature signal;

a first power amplifier for amplifying the in-phase signal to produce a first amplified signal;

a second power amplifier for amplifying the quadrature signal to produce a second amplified signal; and

a second hybrid circuit for inverting the first amplified signal to produce an inverted signal and for summing the inverted signal and the second amplified signal,

said bypass path connecting an output of said driver amplifier and an isolated port of said second hybrid circuit when said first switch switches the analog signal to said bypass path.

32. The mobile communication unit of claim 31, wherein said power amplifier circuit arrangement further comprises:

a second switch positioned in said bypass path; and

a terminating resistor connected to a pole of said second switch;

said second switch selectively connecting the isolated port of said second hybrid circuit with either said first switch or said terminating resistor.

33. The mobile communication unit of claim 31, wherein said power amplifier circuit arrangement further comprises:

a first shunt switch positioned between said first power amplifier and said second hybrid; and

a second shunt switch positioned between said second power amplifier and said second hybrid circuit;

said first and second shunt switches being used to shunt the output of said first and second power amplifiers, respectively, when using said bypass path.