Amplifier dynamic bias adjustment for envelope tracking

• US 9,973,145 B2
• Filed: 12/03/2015
• Issued: 05/15/2018
• Est. Priority Date: 12/28/2012
• Status: Active Grant

• Current Assignee: pSemi Corporation (Murata Manufacturing Co Limited)
• Original Assignee: pSemi Corporation (Murata Manufacturing Co Limited)
• Inventors: Nobbe, Dan William, Dykstra, Jeffrey A., Olson, Chris, Cable, James S.
• Primary Examiner(s): Nguyen, Khanh V
• Assistant Examiner(s): NGUYEN, KHIEM D
• Application Number:
  US14/958,848
• Publication Number:
  US 20160164469A1
• Time in Patent Office: 894 Days
• Field of Search: 330136, 330127, 330295, 330296, 330297
• CPC Class Codes: H03D 1/18 of semiconductor devices
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 1/0216 Continuous control
• CPC Class Codes: H03F 1/0222 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/0227 using supply converters
• CPC Class Codes: H03F 1/0244 Stepped control
• CPC Class Codes: H03F 1/025 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 1/223 with MOSFET's
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3282 Acting on the phase and the amplitude of the input signal
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03F 2200/102 A non-specified detector of a signal envelope being used in an amplifying circuit
• CPC Class Codes: H03F 2200/108 A coil being added in the drain circuit of a FET amplifier stage, e.g. for noise reducing purposes
• CPC Class Codes: H03F 2200/129 there being a feedback over the complete amplifier
• CPC Class Codes: H03F 2200/15 the supply or bias voltage or current at the drain side of a FET being continuously controlled by a controlling signal
• CPC Class Codes: H03F 2200/18 the bias of the gate of a FET being controlled by a control signal
• CPC Class Codes: H03F 2200/213 A variable capacitor being added in the input circuit, e.g. base, gate, of an amplifier stage
• CPC Class Codes: H03F 2200/222 A circuit being added at the input of an amplifier to adapt the input impedance of the amplifier
• CPC Class Codes: H03F 2200/336 A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit
• CPC Class Codes: H03F 2200/387 : A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier
• CPC Class Codes: H03F 2200/408 : the output amplifying stage of an amplifier comprising three power stages
• CPC Class Codes: H03F 2200/411 : the output amplifying stage of an amplifier comprising two power stages
• CPC Class Codes: H03F 2200/451 : the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/534 : Transformer coupled at the input of an amplifier
• CPC Class Codes: H03F 2200/537 : A transformer being used as coupling element between two amplifying stages
• CPC Class Codes: H03F 2200/541 : Transformer coupled at the output of an amplifier
• CPC Class Codes: H03F 2200/546 : A tunable capacitance being present in an amplifier circuit
• CPC Class Codes: H03F 2200/78 : A comparator being used in a controlling circuit of an amplifier
• CPC Class Codes: H03F 2201/3233 : Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion
• CPC Class Codes: H03F 2203/45112 : the biasing of the differential amplifier being controlled from the input or the output signal
• CPC Class Codes: H03F 2203/45366 : the AAC comprising multiple transistors parallel coupled at their gates only, e.g. in a cascode dif amp, only those forming the composite common source transistor
• CPC Class Codes: H03F 2203/45544 : the IC comprising one or more capacitors, e.g. coupling capacitors
• CPC Class Codes: H03F 2203/45638 : the LC comprising one or more coils
• CPC Class Codes: H03F 2203/45731 : the LC comprising a transformer
• CPC Class Codes: H03F 3/191 : Tuned amplifiers H03F3/193, H03F3/195 take precedence
• CPC Class Codes: H03F 3/193 : with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/195 : in integrated circuits
• CPC Class Codes: H03F 3/21 : with semiconductor devices only H03F3/245 takes precedence
• CPC Class Codes: H03F 3/211 : using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/24 : of transmitter output stages
• CPC Class Codes: H03F 3/45179 : using MOSFET transistors as the active amplifying circuit H03F3/45278 takes precedence
• CPC Class Codes: H03F 3/45183 : Long tailed pairs H03F3/4521, H03F3/45237 take precedence
• CPC Class Codes: H03F 3/45188 : Non-folded cascode stages

Abstract

An envelope tracking amplifier having stacked transistors is presented. The envelope tracking amplifier uses dynamic bias voltages at one or more gates of the stacked transistors in addition to a dynamic bias voltage at a drain of a transistor.

Claims

1. A circuital arrangement comprising:

an amplifier comprising;

stacked transistors having a plurality of gate terminals configured to operatively provide a plurality of dynamic bias voltages or currents to the stacked transistors;

an input port operatively connected to a gate terminal of an input transistor of the stacked transistors configured to receive a radio frequency (RF) signal;

an output port operatively connected to an output transistor of the stacked transistors configured to output an amplified version of the RF signal; and

a reference terminal operatively coupling the input transistor to a reference potential, wherein the stacked transistors comprise a first subset and a second subset of transistors operatively arranged in series;

a) the first subset comprising the input transistor operatively connected between the reference potential at the reference terminal and the second subset; and

b) the second subset comprises;

i) one or more transistors operatively connected in series with each other, at least one transistor of the one or more transistors being the output transistor, the second subset operatively connected between the first subset and a variable output supply bias voltage or current provided to a drain terminal of the output transistor; and

ii) one or more gate capacitors, each gate capacitor of the one or more gate capacitors connected between a respective gate terminal of each transistor of the one or more transistors of the second subset and the reference potential, wherein the each gate capacitor is configured to allow a gate voltage at the respective gate terminal to vary along with a radio frequency (RF) voltage at a drain of the each transistor.

2. The circuital arrangement according to claim 1, further comprising a variable voltage or current source operatively coupled to the circuital arrangement and configured to output one or more variable voltages or currents according to a control signal applied to the variable voltage or current source.

3. The circuital arrangement according to claim 2, wherein the control signal is a function of an envelope signal of an input signal to the amplifier, such as the applying of the control signal impresses said function upon the one or more variable voltages or currents output by the variable voltage or current source.

4. The circuital arrangement according to claim 3, wherein the amplifier is configured to operate in at least one of:

a) linear region, b) compression region, or c) switching between compression and linear regions.

5. The circuital arrangement according to claim 4, wherein the dynamic bias voltages or currents are operatively generated from a first variable voltage or current of the one or more variable voltages or currents and the variable output supply bias voltage or current is operatively generated from a second variable voltage or current of the one or more variable voltages or currents.

6. The circuital arrangement according to claim 1, wherein the one or more capacitors are configured to perform any combination of:

a) optimize a bias voltage across each of the one or more transistors for a desired operation of the amplifier, b) optimize an envelope signal voltage across each of the one or more transistors for a desired operation of the amplifier, and c) optimize an RF voltage swing across each of the one or more transistors for a desired operation of the amplifier.

7. The circuital arrangement according to claim 1, further comprising one or more resistors connected in series between the gate terminals of the one more transistors of the second subset and the provided plurality of dynamic bias voltages or currents.

8. The circuital arrangement according to claim 5 further comprising a circuital arrangement connected in series between at least one gate terminal of the one or more transistors of the second subset and the provided plurality of dynamic bias voltages or currents, the circuital arrangement comprising at least one active device.

9. The circuital arrangement according to claim 8, wherein the circuital arrangement is configured to operate in a frequency range spanning from DC to a frequency content of the input signal.

10. The circuital arrangement according to claim 5, wherein at least one of the plurality of the dynamic bias voltages or currents is generated from the first variable voltage or current using a gate modifier function, wherein the gate modifier function comprises at least one of:

a) a scaling function, b) an amplitude shifting function, c) a phase shifting function, and d) an inverting function.

11. The circuital arrangement according to claim 10 further comprising a gate modifier circuital arrangement to generate said gate modifier function, wherein the gate modifier circuital arrangement comprises at least one of:

a) a resistive-inductive-capacitive (RLC) network, b) a current mirror, c) one or more operational amplifiers, and d) one or more digital integrated circuits.

12. The circuital arrangement according to claim 11, wherein the first variable voltage or current is different from the second variable voltage or current.

13. The circuital arrangement according to claim 11, wherein the first variable voltage or current is the same as the second variable voltage or current.

14. The circuital arrangement according to claim 12, wherein the gate terminal of the input transistor is adapted to receive a bias input gate voltage or current which is not generated from the first or the second variable voltage or current.

15. The circuital arrangement according to claim 13, wherein the gate terminal of the input transistor is adapted to receive a bias input gate voltage or current which is not generated from the first or the second variable voltage or current.

16. The circuital arrangement according to claim 5, wherein the gate terminal of the input transistor is adapted to receive a bias input gate voltage or current which is not generated from the first or the second variable voltage or current.

17. The circuital arrangement according to claim 5, further comprising an inductor configured as a choke operatively connected between the output transistor and the variable output supply bias voltage or current provided to the output transistor.

18. The circuital arrangement according to claim 5, wherein the variable voltage or current source is a DC-DC converter.

19. The circuital arrangement according to claim 5, wherein the variable voltage or current source is a DC-DC converter and a linear regulator operatively connected in parallel or in series with each other.

20. The circuital arrangement according to claim 5, wherein the variable voltage or current source is operatively coupled to the drain terminal of the output transistor and is adapted to vary a voltage of the variable output supply bias voltage or current.

21. The circuital arrangement according to claim 5, wherein the variable voltage or current source is operatively coupled to a source terminal of the input transistor and is adapted to vary a current of the variable output supply bias voltage or current.

22. The circuital arrangement according to claim 5, wherein a direct current (DC) component of an at least one of the plurality of the dynamic bias voltages or currents is not operatively generated from the first variable voltage or current.

23. The circuital arrangement according to claim 5, wherein the stacked transistors are configured in a cascode configuration.

24. The circuital arrangement according to claim 5, wherein the stacked transistors are configured in a differential cascode configuration and further comprise differential input and output ports operatively coupled to differential pairs of input and output transistors of the differential cascode configuration.

25. The circuital arrangement according to claim 5, wherein the amplifier is a driver or a final stage amplifier.

26. The circuital arrangement according to claim 5, wherein the reference potential is one of a) a reference ground, b) a virtual ground, and c) an RF ground.

27. The circuital arrangement according to claim 5, wherein the stacked transistors are field effect transistors (FETs) or bipolar junction transistors (BJTs).

28. The circuital arrangement according to claim 5, wherein the amplifier is configured to amplify an input signal with a frequency content above 100 MHz provided at the input port of the amplifier, and reproduce an amplified output signal at the output port of the amplifier, wherein a measured power of the amplified output signal into an output load is above 50 mW.

29. The circuital arrangement according to claim 5, wherein the amplifier is configured to amplify an input signal with a frequency content below 100 MHz provided at the input port of the amplifier, and reproduce an amplified output signal at the output port of the amplifier, wherein a measured power of the amplified output signal into an output load is above 50 mW.

30. The circuital arrangement according to claim 15, wherein the stacked transistors comprise one of:

a) three transistors, b) four transistors, c) five transistors, and d) more than five transistors in a stacked configuration.

31. The circuital arrangement according to claim 1, wherein the variable output supply bias voltage or current is operatively generated from an envelope signal of an input signal.

32. The circuital arrangement according to claim 1, wherein at least one of the plurality of the dynamic bias voltages or currents is operatively generated using an arbitrary function.

33. The circuital arrangement according to claim 31, wherein at least one of the plurality of the dynamic bias voltages or currents is operatively generated from the envelope signal of the input signal using a gate modifier function, wherein the gate modifier function comprises at least one of:

a) a scaling function, b) an amplitude shifting function, c) a phase shifting function, and d) an inverting function.

34. The circuital arrangement according to claim 31, wherein at least one of the plurality of the dynamic bias voltages or currents is operatively generated from the variable output supply bias voltage or current using a gate modifier function, wherein the gate modifier function comprises at least one of:

a) a scaling function, b) an amplitude shifting function, c) a phase shifting function, and d) an inverting function.

35. The circuital arrangement according to claim 33 further comprising a gate modifier circuital arrangement to generate said gate modifier function, wherein the gate modifier circuital arrangement comprises at least one of:

a) a resistive-inductive-capacitive (RLC) network, b) a current mirror, c) one or more operational amplifiers, and d) one or more digital integrated circuits.

36. The circuital arrangement according to claim 34 further comprising a gate modifier circuital arrangement to generate said gate modifier function, wherein the gate modifier circuital arrangement comprises at least one of:

a) a resistive-inductive-capacitive (RLC) network, b) a current mirror, c) one or more operational amplifiers, and d) one or more digital integrated circuits.

37. The circuital arrangement according to claim 33, wherein phase shifting of at least one of the plurality of the dynamic bias voltages or currents is used as a pre-distortion operation of an at least one corresponding transistor of the stacked transistors such as to compensate for unintended effects of providing the variable output drain voltage or current to the output transistor.

38. The circuital arrangement according to claim 34, wherein phase shifting of at least one of the plurality of the dynamic bias voltages or currents is used as a pre-distortion operation of an at least one corresponding transistor of the stacked transistors such as to compensate for unintended effects of providing the variable output drain voltage or current to the output transistor.

39. The circuital arrangement according to claim 35 or claim 36, wherein generating of the gate modifier function for the input transistor comprises a current mirror.

40. A method of amplifying a radio frequency (RF) signal in a circuital arrangement, the method comprising:

providing an amplifier comprising stacked transistors in a cascode configuration;

connecting, for each transistor of the stacked transistors with the exception of an input transistor of the stacked transistors, gate capacitor between a gate terminal of the each transistor and a reference potential;

adapting the circuital arrangement to operatively connect a plurality of bias supplies to a plurality of gate terminals of the stacked transistors and to a drain terminal of an output transistor of the stacked transistors;

applying an input RF signal to an input port of the circuital arrangement operatively connected to the input transistor of the stacked transistors;

varying a bias supply of the plurality of bias supplies operatively connected to the drain of the output transistor, and

impressing a desired amplification on the input RF signal to obtain an amplified output RF signal by varying at least one bias supply of the plurality of bias supplies operatively connected to a gate terminal of one transistor of the stacked transistors,

wherein each gate capacitor is configured to allow a voltage at a gate of a corresponding transistor to vary along with an RF voltage at a drain of the corresponding transistor.

41. The method of claim 40, wherein varying the bias supply operatively connected to the drain of the output transistor is based on an envelope signal of the input RF signal applied to the input port of the circuital arrangement.

42. The method of claim 40, wherein varying the at least one bias supply comprises applying to the gate terminal of the one transistor a signal obtained by applying at least one of:

a) a scaling function, b) an amplitude shifting function, c) a phase shifting function, and d) an inverting function, to an envelope signal of the input signal.

43. The method of claim 42, wherein the scaling, amplitude shifting, phase shifting or inverting functions are implemented using at least one of:

a) RLC networks, b) circuital arrangements including op-amps, or c) circuital arrangements including digital ICs.

44. A circuital arrangement comprising:

an amplifier comprising;

stacked transistors having a plurality of gate terminals configured to operatively provide a plurality of dynamic bias voltages or currents to the stacked transistors;

a variable voltage or current source operatively coupled to the stacked transistors, the variable voltage or current source comprising a DC/DC converter;

an input port operatively connected to a gate terminal of an input transistor of the stacked transistors configured to receive a radio frequency (RF) signal;

an output port operatively connected to an output transistor of the stacked transistors configured to output an amplified version of the RF signal; and

a reference terminal operatively coupling the input transistor to a reference potential, wherein the stacked transistors comprise a first subset and a second subset of transistors operatively arranged in series, wherein;

a) the first subset comprises the input transistor operatively connected between the reference potential at the reference terminal and the second subset; and

b) the second subset comprises;

i) one or more transistors operatively connected in series with each other, at least one transistor of the one or more transistors being the output transistor, the second subset operatively connected between the first subset and a variable output supply bias voltage or current provided to a drain terminal of the output transistor; and

ii) one or more gate capacitors connected between gate terminals of the one or more transistors of the second subset and the reference potential, wherein each gate capacitor of the one or more gate capacitors is configured to allow a gate voltage at a gate terminal of a transistor of the one or more transistors of the second subset to vary along with a radio frequency (RF) voltage at a drain of the transistor, and

c) the dynamic bias voltages or currents, and the variable output supply bias voltage or current, are operatively generated from the variable voltage or current source.

45. A method of amplifying a radio frequency (RF) signal in a circuital arrangement, the method comprising:

providing an amplifier comprising stacked transistors in a cascode configuration;

connecting, for all transistors of the stacked transistors with the exception of an input transistor of the stacked transistors, gate capacitors between gate terminals of corresponding transistors of the stacked transistors and a reference potential;

adapting the circuital arrangement to operatively connect a plurality of bias supplies to a plurality of gate terminals of the stacked transistors and to a drain terminal of an output transistor of the stacked transistors;

applying an input RF signal to an input port of the circuital arrangement operatively connected to the input transistor of the stacked transistors;

varying, by way of a variable voltage or current source comprising a DC/DC converter, a bias supply of the plurality of bias supplies operatively connected to the drain of the output transistor, and

impressing a desired amplification on the input RF signal to obtain an amplified output RF signal by varying, by way of the variable voltage or current source, at least one bias supply of the plurality of bias supplies operatively connected to a gate terminal of one transistor of the stacked transistors,

wherein each of the gate capacitors is configured to allow a voltage at a gate of a corresponding transistor to vary along with an RF voltage at a drain of the corresponding transistor.