circuits and methods for use in amplifying amplitude and phase modulated signals. A circuit uses a combiner with dual parallel signal amplifiers feeding it. The signal amplifiers have a low output impedance while the combiner does not provide any isolation between its inputs from the signal amplifiers. As in other Chireix architectures, the signals from the signal amplifiers are phase modulated prior to being fed to the combiner. The combiner then combines these two signals and, depending on how these two signals are combined, the resulting output of the combiner is amplitude modulated. The signal amplifiers may be class D or class f amplifiers to provide high efficiency amplification of the signals.
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0. 27. A method, comprising:
amplifying two or more phase modulated signals received at two or more amplifiers;
combining the two or more amplified signals with a balanced magnetic transformer without requiring a center tap to ground to produce a resulting signal; and
amplitude modulating the resulting signal responsive to the two or more phase modulated signals received at the two or more amplifiers;
wherein outputs of said two or more amplifiers are configured to be coupled to terminals of an input winding of said transformer; and
wherein at least one of the two or more amplifiers is configured to operate as a class f amplifier.
0. 21. An apparatus, comprising:
means for amplifying two or more phase modulated signals; and
means for combining outputs of said means for amplifying produce a resulting signal;
wherein said means for combining includes a balanced magnetic transformer means not requiring a center tap to ground; and
wherein the resulting signal is configured to be amplitude modulated responsive to the two or more phase modulated signals amplified by said means for amplifying;
wherein said outputs of said means for amplifying are configured to be coupled to terminals of an input winding of said transformer means; and
wherein the means for amplifying includes at least one class f amplifier.
0. 13. An apparatus, comprising:
at least two amplifiers each configured to amplify a corresponding phase modulated signal; and
a signal combiner configured to combine outputs of said at least two amplifiers to produce a resulting signal;
wherein said combiner includes a balanced magnetic transformer not requiring a center tap to ground;
wherein the resulting signal is configured to be amplitude modulated via the corresponding phase modulated signal amplified by each of said at least two amplifiers;
wherein at least one of the at least two amplifiers is configured to operate as a class f amplifier; and
wherein said outputs of said at least two amplifiers are configured to be coupled to terminals of an input winding of said transformer.
0. 25. An apparatus, comprising:
means for amplifying two or more phase modulated signals; and
means for combining outputs of said means for amplifying to generate a resulting signal;
wherein said means for combining is configured to provide little or no isolation between the outputs of said means for amplifying;
wherein said means for combining includes means for changing a voltage of a varying current and does not require a center tap means to ground connection;
wherein the resulting signal is configured to be amplitude modulated via the two or more phase modulated signals amplified by said means for amplifying;
wherein said means for amplifying is configured to operate as at least one class f amplifier; and
wherein said outputs of said means for amplifying are configured to be coupled to terminals of an input winding of said means for combining.
0. 31. A method, comprising:
amplifying two or more phase modulated signals corresponding to two or more amplifiers; and
combining the two or more amplified signals with a balanced magnetic transformer without requiring a center tap to ground to produce a resulting signal;
wherein said combining includes providing little or no isolation between the two or more signals;
wherein said amplifying includes operating the two or more amplifiers in a switch mode;
wherein said combining includes amplitude modulating the resulting signal responsive to the two or more phase modulated signals corresponding to the two or more amplifiers;
wherein outputs of said two or more amplifiers are configured to be coupled to terminals of an input winding of said transformer; and
wherein at least one of the two or more amplifiers is configured to operate as a class f amplifier.
0. 38. A wireless device, comprising:
a baseband processor; and
a radio-frequency transmitter coupled to said baseband processor, comprising:
at least two amplifiers configured to amplify corresponding phase modulated signals; and
a signal combiner configured to combine outputs from said at least two amplifiers to generate a resulting signal;
wherein said signal combiner includes a balanced magnetic transformer not requiring a center tap to ground connection;
wherein the resulting signal is configured to be amplitude modulated responsive to the phase modulated signal corresponding to each of said at least two amplifiers;
wherein said outputs of said at least two amplifiers are configured to be coupled to terminals of an input winding of said transformer; and
wherein at least one of the at least two amplifiers is configured to operate as a class f amplifier.
0. 18. An apparatus, comprising:
at least two amplifiers configured to amplify a corresponding phase modulated signal; and
a signal combiner configured to combine outputs from said at least two amplifiers to generate a resulting signal;
wherein said signal combiner is configured to provide little or no isolation between the outputs of said at least two amplifiers;
wherein said signal combiner includes a balanced magnetic transformer not requiring a center tap to ground connection;
wherein the resulting signal is capable of being amplitude modulated via the corresponding phase modulated signal amplified by each of said at least two amplifiers;
wherein one of said at least two amplifiers is configured to operate as a class f amplifier; and
wherein said outputs of said at least two amplifiers are configured to be coupled to terminals of an input winding of said transformer.
0. 33. A wireless device, comprising:
a baseband processor; and
a radio-frequency transmitter coupled to said baseband processor, said radio-frequency transmitter comprising;
at least two amplifiers each configured to amplify a corresponding phase modulated signal; and
a signal combiner configured to combine outputs of said at least two low output impedance amplifiers to produce a resulting signal;
wherein said combiner includes a balanced magnetic transformer not requiring a center tap to ground connection;
wherein the resulting signal is capable of being amplitude modulated via the phase modulated signals corresponding to each of said at least two amplifiers;
wherein said outputs of said at least two amplifiers are configured to be coupled to terminals of an input winding of said transformer; and
wherein at least one of the at least two amplifiers is configured to operate as a class f amplifier.
1. A circuit for providing amplification to signals, the circuit comprising:
a signal combiner, wherein said combiner is a modified balanced magnetic transformer, said transformer being devoid of a center tap to ground connection;
at least two signal amplifiers each receiving and amplifying a signal, said signal amplifiers being coupled in parallel to said combiner, each of said signal amplifiers having a low output impedance and acting as a voltage source, wherein each signal received and amplified by each of said signal amplifiers is phase modulated, and wherein at least one of the at least two amplifiers is configured to operate as a class f amplifier;
outputs of each of said signal amplifiers are added by said combiner to produce a resulting signal, said signal amplifier outputs being coupled to terminals of an input winding of said transformer; and
amplitude modulation of said resulting signal from said combiner is achieved by an addition of said outputs.
7. A circuit for providing amplification to signals, the circuit comprising:
at least two signal amplifiers each receiving and amplifying a phase modulated signal and, each producing an amplifier output, and at least one of the at least two signal amplifiers operating as a class f amplifier; and
a signal combiner receiving each of said amplifier outputs in parallel, said signal combiner providing no isolation between said amplifier outputs,
wherein
each signal received and amplified by each of said signal amplifiers is phase modulated;
said signal combiner is a modified balanced magnetic transformer, said transformer being devoid of a center tan tap to ground connection;
said amplifier outputs are added by said combiner to produce a resulting signals signal,
said amplifier outputs being coupled to terminals of an input winding of said transformer; and
amplitude modulation of said resulting signal from said combiner is achieved by an addition of said amplifier outputs.
2. A circuit according to
3. A circuit according to
0. 5. A circuit according to
class D signal amplifiers; and
class f signal amplifiers.
6. A circuit according to
0. 8. A circuit according to
9. A circuit according to claim 8 7 wherein each of said signal amplifiers has switch mode operation.
0. 10. A circuit according to
class D signal amplifiers; and
class f signal amplifiers.
0. 11. A circuit according to
class D signal amplifiers; and
class f signal amplifiers.
0. 12. A circuit according to
0. 14. The apparatus of claim 13, wherein said combiner is configured to provide minimum isolation between the outputs of said at least two amplifiers.
0. 15. The apparatus of claim 13, wherein said combiner is configured to provide little or no isolation between the outputs of said at least two amplifiers.
0. 16. The apparatus of claim 13, wherein one or more of said at least two amplifiers is configured to operate in a switch mode.
0. 17. The apparatus of claim 13, wherein all or nearly all of said at least two amplifiers include a substantially similar type of amplifier.
0. 19. The apparatus of claim 18, wherein one or more of said at least two amplifiers includes a low output impedance.
0. 20. The apparatus of claim 18, wherein one of said at least two amplifiers includes a same or similar type of amplifier.
0. 22. The apparatus of claim 21, wherein said means for combining is configured to provide a minimum isolation between the outputs of said amplifying means.
0. 23. The apparatus of claim 21, wherein said means for combining is configured to provide little or no isolation between the outputs of said means for amplifying.
0. 24. The apparatus of claim 21, wherein said means for amplifying is configured to operate in a switch mode.
0. 26. The apparatus of claim 25, wherein said means for amplifying includes a low output impedance.
0. 28. The method of claim 27, wherein said combining includes providing a minimum isolation between the two or more amplified signals.
0. 29. The method of claim 27, wherein said combining includes providing little or no isolation between the two or more amplified signals.
0. 30. The method of claim 27, wherein said amplifying includes operating in a switch mode.
0. 32. The method of claim 31, wherein said amplifying includes amplifying using two or more low output impedance amplifiers.
0. 34. The wireless device of claim 33, wherein said combiner is configured to provide a minimum isolation between the outputs of said at least two amplifiers.
0. 35. The wireless device of claim 33, wherein said combiner is configured to provide little or no isolation between the outputs of said at least two amplifiers.
0. 36. The wireless device of claim 33, wherein one or more of said at least two amplifiers is configured to operate in a switch mode.
0. 37. The wireless device of claim 33, wherein all or nearly all of said at least two amplifiers include a same or similar type of amplifier.
0. 39. The wireless device of claim 38, wherein one or more of said at least two amplifiers includes a low output impedance.
0. 40. The wireless device of claim 38, wherein one or more of said at least two amplifiers includes a same or similar type of amplifier.
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The present invention relates to signal processing and is particularly applicable but not limited to circuits for amplifying amplitude and phase modulated signals.
The communications revolution of the 1990's has led to an increasing need for further and better means of transporting both data and voice communications. One offshoot of this revolution has been the burgeoning growth in wireless communications as more and more data is being transmitted by wireless means. For wireless handsets, wireless PDAs (personal digital assistants), and other wireless devices, one overarching concern is power consumption—the less power a device consumes the more desirable it is. To this end, higher efficiency components, such as amplifiers, are desirable in these wireless devices.
One type of architecture which was used in the past but has fallen out of recent favor is the so called Chireix architecture. First suggested by Henry Chireix in 1935, the technique also known as “outphasing” involves separately phase modulating two signals and recombining them in a combiner or combining network. By judiciously adjusting the phase modulation of the two signals, the combined resulting signal can become amplitude modulated as well as phase modulated. This technique enables the use of saturated amplifiers or switching amplifiers for amplitude modulated signals.
Also called “ampliphase” by the RCA Corporation when used in some of their radio transmitters, the technique has recently fallen out of favor due to its seeming inapplicability when amplifying signals. Previous attempts used common forms of linear and saturating amplifiers such as Class A and Class AB amplifiers to try and amplify the two signals prior to their being combined. Unfortunately, these efforts have yielded unacceptable results as the resulting circuits were found to be insufficiently efficient. A Chireix based architecture, if properly working with sufficient efficiency, would offer advantages in not only power consumption but in other areas as well.
Based on the above, there is a need for, methods or circuits which overcome or at least mitigate the drawback of the prior art. Such a solution should provide the advantages of a Chireix or outphasing architecture while providing sufficient amplification efficiency to be useful.
The present invention provides circuits and methods for use in amplifying amplitude and phase modulated signals. A circuit uses a combiner with dual parallel signal amplifiers feeding it. The signal amplifiers have a low output impedance while the combiner does not provide any isolation between its inputs from the signal amplifiers. As in other Chireix architectures, the signals from the signal amplifiers are phase modulated prior to being fed to the combiner. The combiner then combines these two signals and, depending on how these two signals are phase modulated, the resulting output of the combiner is amplitude modulated as well as phase modulated. The signal amplifiers may be Class D or Class F amplifiers to provide high efficiency amplification of the signals.
In a first aspect, the present invention provides a circuit for providing amplification to signals, the circuit comprising:
In a second aspect, the present invention provides a circuit for providing amplification to signals, the circuit comprising:
A better understanding of the invention will be obtained by considering the detailed description below, with reference to the following drawings in which:
Referring to
As in well known Chireix architectures, the signals received and amplified by the signal amplifiers 20a, 20B are phase modulated signals. These phase modulated signals, after being amplified by the signal amplifiers 20A, 20B, are combined or added by the combiner 30 to result in the output signal 40. By judiciously phase modulating the signals using appropriate phase modulators (not shown), the resulting signal 40 from the addition of the two signals is an amplitude modulated signal. Not only that, but the resulting signal is, in effect, an amplified version of a phase and an amplitude modulated signal.
It should be noted that similar architectures as that illustrated in
The dynamic nature of the load impedance is a result of the appropriate combiner for a Chireix architecture. Such an appropriate combiner not only reinserts the amplitude modulation to the resulting signal 40, it also provides a dynamic adjustment of the load impedance presented to each one of the signal amplifiers. This outphasing adjustment of the load impedance is such that the DC current through each signal amplifier decreases as the combined output amplitude decreases thereby maintaining high efficiency.
Two appropriate combiners are illustrated in
Another appropriate combiner is a modified Wilkinson combiner 110 as illustrated in
Regarding a proper choice of amplifiers for use in the block diagram of
As is known, Class F amplifiers provide a good approximation to a voltage square-wave across the output terminals of a device by “shorting” all even-harmonic voltages and “supporting” all odd-harmonic voltages. As a result, the voltage waveform across the output terminals of a device contains only odd-harmonic components. In addition, this sorting of odd- and even-harmonics results in a current passing through the output terminals of the device that contains the fundamental, and only even-harmonic components.
This “shorting” and “supporting” of harmonics is conveniently achieved with a shorted quarter-wave shunt-stub connected across the device's output terminals, a shown in
In a practical situation, with a stub effectively shorting only the second harmonic voltage, and passing only the fundamental and third harmonic voltage, the power-added efficiency can be more than 85%.
As an example of a Class D amplifier which may be used with the invention,
For such Class D (voltage switching) amplifiers, the active device passes no current between its output terminals when the voltage across its output terminals is at the voltage rail, and passes maximum current between its output terminals when the voltage across its output terminals is zero. As a result, the device does not absorb any power, and all power taken from the bias supply is converted into the output signal (100% power-added efficiency).
It should be noted that the amplifiers in the amplifier pair 20A, 20B in
It should also be noted that while the circuit of
A person understanding this invention may now conceive of alternative structures and embodiments or variations of the above all of which are intended to fall within the scope of the invention as defined in the claims that follow.
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