Chireix architecture using low impedance amplifiers

Abstract

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.

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. 
 
     
     
       2. A circuit according to  claim 1  wherein said combiner provides minimum isolation between said outputs of said signal amplifiers. 
     
     
       3. A circuit according to  claim 1  wherein said combiner provides no isolation between said outputs of said signal amplifiers. 
     
     
       4. A circuit according to  claim 1  wherein each of said amplifiers has switch mode operation. 
     
     
       5. A circuit according to  claim 4  wherein each of said amplifiers is chosen from a group comprising:
 class D signal amplifiers; and 
 class F signal amplifiers. 
 
     
     
       6. A circuit according to  claim 1  wherein all of said at least two signal amplifiers are of the same type. 
     
     
       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. 
 
     
     
       8. A circuit according to  claim 7  wherein each of said signal amplifiers has a very low output impedance. 
     
     
       9. A circuit according to claim  8  7 wherein each of said signal amplifiers has switch mode operation. 
     
     
       10. A circuit according to  claim 9  wherein each of said signal amplifiers is chosen from a group comprising:
 class D signal amplifiers; and 
 class F signal amplifiers. 
 
     
     
       11. A circuit according to  claims 7  wherein each of said signal amplifiers is chosen from a group comprising:
 class D signal amplifiers; and 
 class F signal amplifiers. 
 
     
     
       12. A circuit according to  claim 7  wherein all of said at least two signal amplifiers are of the same type. 
     
     
       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.   
     
     
       14. The apparatus of claim 13, wherein said combiner is configured to provide minimum isolation between the outputs of said at least two amplifiers. 
     
     
       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. 
     
     
       16. The apparatus of claim 13, wherein one or more of said at least two amplifiers is configured to operate in a switch mode. 
     
     
       17. The apparatus of claim 13, wherein all or nearly all of said at least two amplifiers include a substantially similar type of amplifier. 
     
     
       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.   
     
     
       19. The apparatus of claim 18, wherein one or more of said at least two amplifiers includes a low output impedance. 
     
     
       20. The apparatus of claim 18, wherein one of said at least two amplifiers includes a same or similar type of amplifier. 
     
     
       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.   
     
     
       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. 
     
     
       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. 
     
     
       24. The apparatus of claim 21, wherein said means for amplifying is configured to operate in a switch mode. 
     
     
       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.   
     
     
       26. The apparatus of claim 25, wherein said means for amplifying includes a low output impedance. 
     
     
       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.   
     
     
       28. The method of claim 27, wherein said combining includes providing a minimum isolation between the two or more amplified signals. 
     
     
       29. The method of claim 27, wherein said combining includes providing little or no isolation between the two or more amplified signals. 
     
     
       30. The method of claim 27, wherein said amplifying includes operating in a switch mode. 
     
     
       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.   
     
     
       32. The method of claim 31, wherein said amplifying includes amplifying using two or more low output impedance amplifiers. 
     
     
       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. 
   
     
     
       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. 
     
     
       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. 
     
     
       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. 
     
     
       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. 
     
     
       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. 
   
     
     
       39. The wireless device of claim 38, wherein one or more of said at least two amplifiers includes a low output impedance. 
     
     
       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.