Amplifier circuit

Abstract

An amplifier circuit for amplifying an input signal to generate an amplifier output signal incorporates a cascaded series of reflection amplifiers arranged along a signal path and operative to amplify signals propagating in a forward direction along the signal path. The circuit is operative to counteract signal propagation in a reverse direction along the signal path, thereby hindering spontaneous oscillation from arising within the circuit. Incorporation of reflection amplifiers into the circuit enables it to provide high gain, for example 50 dB, while consuming low currents, for example, tens of microamperes. The circuit is especially suitable for use at intermediate frequencies in radio receivers such as mobile telephones.

1. An amplifier circuit for receiving an input signal and providing a corresponding amplified output signal, the circuit comprising:
 a) a plurality of reflection amplifiers cascaded in series along a signal path and operative to amplify the input signal propagating in a forward direction therealong to provide the output signal; and  
 b) connecting means for connecting the reflection amplifiers to form the signal path and for hindering signal propagation in a reverse direction therealong, thereby counteracting spontaneous oscillation from arising within the circuit, the connecting means incorporating filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from the associated sideband signal components along the path, the filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong.  
 
     
     
       2. The circuit according to  claim 1 , wherein the filters are arranged in series along the signal path, the filters alternating between sideband transmissive filters and sideband rejective filters along the path, and the modulating means is arranged to convert the input signal as it propagates along the signal path alternately between a corresponding carrier signal transmissible substantially through the sideband rejective filters only and a corresponding sideband signal transmissible substantially through the sideband transmissive filters only, thereby promoting input signal propagation in the forward direction along the path and hindering signal propagation in the reverse direction therealong. 
     
     
       3. The circuit according to  claim 1 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective reflection amplifier associated therewith. 
     
     
       4. The circuit according to  claim 3 , wherein the phase switches are interposed between the filters and their associated amplifiers. 
     
     
       5. The circuit according to  claim 1 , wherein the modulating means is operable at a rate having an associated frequency which is half a frequency separation of transmission peaks of the sideband transmission characteristics of the si and  sideband transmissive filters. 
     
     
       6. The circuit according to  claim 3 , wherein the phase switches each incorporate a tuned circuit comprising an inductor and a modulated varactor. 
     
     
       7. An intermediate frequency strip incorporating an amplifier circuit for receiving an input signal and providing a corresponding amplified output signal, the circuit comprising:
 a) a plurality of reflection amplifiers cascaded in series along a signal path and operative to amplify the input signal propagating in a forward direction therealong to provide the output signal; and  
 b) connecting means for connecting the reflection amplifiers to form the signal path and for hindering signal propagation in a reverse direction therealong, thereby counteracting spontaneous oscillation from arising within the circuit, the connecting means incorporating filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from the associated sideband signal components along the path, the filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong.  
 
     
     
       8. An intermediate frequency receiver incorporating an amplifier circuit for receiving an input signal and providing a corresponding amplified output signal, the circuit comprising:
 a) a plurality of reflection amplifiers cascaded in series along a signal path and operative to amplify the input signal propagating in a forward direction therealong to provide the output signal; and  
 b) connecting means for connecting the reflection amplifiers to form the signal path and for hindering signal propagation in a reverse direction therealong, thereby counteracting spontaneous oscillation from arising within the circuit, the connecting means incorporating-filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from the associated sideband signal components along the path, the filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong.  
 
     
     
       9. A mobile telephone incorporating an amplifier circuit for receiving an input signal and providing a corresponding amplified output signal, the circuit comprising:
 a) a plurality of reflection amplifiers cascaded in series along a signal path and operative to amplify the input signal propagating in a forward direction therealong to provide the output signal; and  
 b) connecting means for connecting the reflection amplifiers to form the signal path and for hindering signal propagation in a reverse direction therealong, thereby counteracting spontaneous oscillation from arising within the circuit, the connecting means incorporating-filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from the associated sideband signal components along the path, the filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong.  
 
     
     
       10. A method of amplifying an input signal and providing a corresponding amplified output signal, the method comprising the steps of:
 a) providing a plurality of reflection amplifiers cascaded in series along a signal path, and connecting means for connecting the reflection amplifiers to the signal path and operative to promote signal propagation in a forward direction along the path and counteract signal propagation in a reverse direction therealong, the connecting means incorporating filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from associated sideband signal components along the path, the filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong;  
 b) receiving the input signal at the signal path;  
 c) directing the input signal through the connecting means to one of the reflection amplifiers for amplification therein to provide an amplified signal;  
 d) directing the amplified signal in the forward direction to another of the reflection amplifiers for further amplification therein;  
 e) repeating step (d) until the amplified signal reaches an output of the signal path; and  
 f) outputting the amplified signal as the output signal from the signal path.  
 
     
     
       11. An amplifier circuit for receiving an input signal and providing a corresponding amplified output signal, the circuit comprising:
   a )  a plurality of reflection amplifiers cascaded in series along a signal path and operative to amplify the input signal propagating in a forward direction therealong to provide the output signal; and        b )  connecting means for connecting the reflection amplifiers to form the signal path and for hindering signal propagation in a reverse direction therealong, thereby counteracting spontaneous oscillation from arising within the circuit, the connecting means incorporating one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from the associated sideband signal components along the path, the one or more filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong.     
     
     
       12. The circuit according to  claim 11 , wherein the one or more filters are arranged in series along the signal path, the one or more filters alternating between sideband transmissive filters and sideband rejective filters along the path, and the modulating means is arranged to convert the input signal as it propagates along the signal path alternately between a corresponding carrier signal transmission substantially through the sideband rejective filters only and a corresponding sideband signal transmissible substantially through the sideband transmissive filters only, thereby promoting input signal propagation in the forward direction along the path and hindering signal propagation in the reverse direction therealong. 
     
     
       13. The circuit according to  claim 11 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective reflection amplifier associated therewith. 
     
     
       14. The circuit according to  claim 13 , wherein the phase switches are interposed between the one or more filters and their associated amplifiers. 
     
     
       15. The circuit according to  claim 13 , wherein the phase switches each incorporate a tuned circuit comprising an inductor and a modulated varactor. 
     
     
       16. The circuit according to  claim 11 , wherein the modulating means is operable at a rate having an associated frequency which is half a frequency separation of transmission peaks of the sideband transmission characteristics of the sideband transmissive filters. 
     
     
       17. The circuit according to  claim 11  further comprising a first filter preceding the first reflection amplifier in the series along the signal path. 
     
     
       18. The circuit according to  claim 17  further comprising a last filter succeeding the last reflection amplifier in the series along the signal path. 
     
     
       19. The circuit according to  claim 18 , wherein the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter are arranged in series along the signal path, all of said filters alternating between sideband transmissive filters and sideband rejective filters along the path, and the modulating means is arranged to convert the input signal as it propagates along the signal path alternately between a corresponding carrier signal transmissible substantially through the sideband rejective filters only and a corresponding sideband signal transmissible substantially through the sideband transmissive filters only, thereby promoting input signal propagation in the forward direction along the path and hindering signal propagation in the reverse direction therealong. 
     
     
       20. The circuit according to  claim 19 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective amplifier associated therewith. 
     
     
       21. The circuit according to  claim 20 , wherein the phase switches are interposed between the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter and their associated amplifiers. 
     
     
       22. The circuit according to  claim 19 , wherein the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter are selected from the group consisting of SAW filters, ceramic filters, tuned inductance/capacitance filters, and bulk acoustic wave filters. 
     
     
       23. The circuit according to  claim 11 , wherein the plurality of reflection amplifiers are connected to a bias controller arranged to control transistor currents within the amplifiers. 
     
     
       24. The circuit according to  claim 19 , wherein the phase switches each incorporate a tuned circuit comprising an inductor and a modulated varactor. 
     
     
       25. An intermediate frequency strip incorporating an amplifier circuit for receiving an input signal and providing a corresponding amplified output signal, the circuit comprising:
   a )  a plurality of reflection amplifiers cascaded in series along a signal path and operative to amplify the input signal propagating in a forward direction therealong to provide the output signal; and        b )  connecting means for connecting the reflection amplifiers to form the signal path and for hindering signal propagation in a reverse direction therealong, thereby counteracting spontaneous oscillation from arising within the circuit, the connecting means incorporating one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from the associated sideband signal components along the path, the one or more filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong.     
     
     
       26. The circuit according to  claim 25 , the one or more filters are arranged in series along the signal path, the one or more filters alternating between sideband transmissive filters and sideband rejective filters along the path, and the modulating means is arranged to convert the input signal as it propagates along the signal path alternately between a corresponding carrier signal transmissible substantially through the sideband rejective filters only and a corresponding sideband signal transmissible substantially through the sideband transmissive filters only, thereby promoting input signal propagation in the forward direction along the path and hindering signal propagation in the reverse direction therealong. 
     
     
       27. The circuit according to  claim 25 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective amplifier associated therewith. 
     
     
       28. The circuit according to  claim 27  wherein the phase switches are interposed between the one or more filters and their associated amplifiers. 
     
     
       29. The circuit according to  claim 25 , wherein the modulating means is operable at a rate having an associated frequency which is half a frequency separation of transmission peaks of the sideband transmission characteristics of the sideband transmissive filters. 
     
     
       30. The circuit according to  claim 25  further comprising a first filter preceding the first reflection amplifier in the series along the signal path. 
     
     
       31. The circuit according to  claim 30  further comprising a last filter succeeding the last reflection amplifier in the series along the signal path. 
     
     
       32. The circuit according to  claim 31 , wherein the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter are arranged in series along the signal path, all of said filters alternating between sideband transmissive filters and sideband rejective filters along the path, and the modulating means is arranged to convert the input signal as it propagates along the signal path alternately between a corresponding carrier signal transmissible substantially through the sideband rejective filters only and a corresponding sideband signal transmissible substantially through the sideband transmissive filters only, thereby promoting input signal propagation in the forward direction along the path and hindering signal propagation in the reverse direction therealong. 
     
     
       33. The circuit according to  claim 32 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective amplifier associated therewith. 
     
     
       34. The circuit according to  claim 33  wherein the phase switches are interposed between the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter and their associated amplifiers. 
     
     
       35. The circuit according to  claim 32 , wherein the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter are selected from the group consisting of SAW filters, ceramic filters, tuned inductance/capacitance filters, and bulk acoustic wave filters. 
     
     
       36. The circuit according to  claim 25 , wherein the plurality of reflection amplifiers are connected to a bias controller arranged to control transistor currents within the amplifiers. 
     
     
       37. An intermediate frequency receiver incorporating an amplifier circuit for receiving an input signal and providing a corresponding amplified output signal, the circuit comprising:
   a )  a plurality of reflection amplifiers cascaded in series along a signal path and operative to amplify the input signal propagating in a forward direction therealong to provide the output signal; and        b )  connecting means for connecting the reflection amplifiers to form the signal path and for hindering signal propagation in a reverse direction therealong, thereby counteracting spontaneous oscillation from arising within the circuit, the connecting means incorporating one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from the associated sideband signal components along the path, the one or more filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong.     
     
     
       38. The circuit according to  claim 37 , the one or more filters are arranged in series along the signal path, the one or more filters alternating between sideband transmissive filters and sideband rejective filters along the path, and the modulating means is arranged to convert the input signal as it propagates along the signal path alternately between a corresponding carrier signal transmissible substantially through the sideband rejective filters only and a corresponding sideband signal transmissible substantially through the sideband transmissive filters only, thereby promoting input signal propagation in the forward direction along the path and hindering signal propagation in the reverse direction therealong. 
     
     
       39. The circuit according to  claim 37 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective amplifier associated therewith. 
     
     
       40. The circuit according to  claim 39 , wherein the phase switches are interposed between the one or more filters and their associated amplifiers. 
     
     
       41. The circuit according to  claim 39 , wherein the phase switches each incorporate a tuned circuit comprising an inductor and a modulated varactor. 
     
     
       42. The circuit according to  claim 37 , wherein the modulating means is operable at a rate having an associated frequency which is half a frequency separation of transmission peaks of the sideband transmission characteristics of the sideband transmissive filters. 
     
     
       43. The circuit according to  claim 37  further comprising a first filter preceding the first reflection amplifier in the series along the signal path. 
     
     
       44. The circuit according to  claim 43  further comprising a last filter succeeding the last reflection amplifier in the series along the signal path. 
     
     
       45. The circuit according to  claim 44 , wherein the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter are arranged in series along the signal path, all of said filters alternating between sideband transmissive filters and sideband rejective filters along the path, and the modulating means is arranged to convert the input signal as it propagates along the signal path alternately between a corresponding carrier signal transmissible substantially through the sideband rejective filters only and a corresponding sideband signal transmissible substantially through the sideband transmissive filters only, thereby promoting input signal propagation in the forward direction along the path and hindering signal propagation in the reverse direction therealong. 
     
     
       46. The circuit according to  claim 45 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective amplifier associated therewith. 
     
     
       47. The circuit according to  claim 46 , wherein the phase switches are interposed between the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter and their associated amplifiers. 
     
     
       48. The circuit according to  claim 45 , wherein the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter are selected from the group consisting of SAW filters, ceramic filters, tuned inductance/capacitance filters, and bulk acoustic wave filters. 
     
     
       49. The circuit according to  claim 37 , wherein the plurality of reflection amplifiers are connected to a bias controller arranged to control transistor currents within the amplifiers. 
     
     
       50. A mobile telephone incorporating an amplifier circuit for receiving an input signal and providing a corresponding amplified output signal, the circuit comprising:
   a )  a plurality of reflection amplifiers cascaded in series along a signal path and operative to amplify the input signal propagating in a forward direction therealong to provide the output signal; and        b )  connecting means for connecting the reflection amplifiers to form the signal path and for hindering signal propagation in a reverse direction therealong, thereby counteracting spontaneous oscillation from arising within the circuit, the connecting means incorporating one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from the associated sideband signal components along the path, the one or more filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong.     
     
     
       51. The circuit according to  claim 50 , the one or more filters are arranged in series along the signal path, the one or more filters alternating between sideband transmissive filters and sideband rejective filters along the path, and the modulating means is arranged to convert the input signal as it propagates along the signal path alternately between a corresponding carrier signal transmissible substantially through the sideband rejective filters only and a corresponding sideband signal transmissible substantially through the sideband transmissive filters only, thereby promoting input signal propagation in the forward direction along the path and hindering signal propagation in the reverse direction therealong. 
     
     
       52. The circuit according to  claim 50 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective amplifier associated therewith. 
     
     
       53. The circuit according to  claim 52 , wherein the phase switches are interposed between the one or more filters and their associated amplifiers. 
     
     
       54. The circuit according to  claim 52 , wherein the phase switches each incorporate a tuned circuit comprising an inductor and a modulated varactor. 
     
     
       55. The circuit according to  claim 50 , wherein the modulating means is operable at a rate having an associated frequency which is half a frequency separation of transmission peaks of the sideband transmission characteristics of the sideband transmissive filters. 
     
     
       56. The circuit according to  claim 50  further comprising a first filter preceding the first reflection amplifier in the series along the signal path. 
     
     
       57. The circuit according to  claim 56  further comprising a last filter succeeding the last reflection amplifier in the series along the signal path. 
     
     
       58. The circuit according to  claim 57 , wherein the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter are arranged in series along the signal path, all of said filters alternating between sideband transmissive filters and sideband rejective filters along the path, and the modulating means is arranged to convert the input signal as it propagates along the signal path alternately between a corresponding carrier signal transmissible substantially through the sideband rejective filters only and a corresponding sideband signal transmissible substantially through the sideband transmissive filters only, thereby promoting input signal propagation in the forward direction along the path and hindering signal propagation in the reverse direction therealong. 
     
     
       59. The circuit according to  claim 58 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective amplifier associated therewith. 
     
     
       60. The circuit according to  claim 59 , wherein the phase switches are interposed between the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter and their associated amplifiers. 
     
     
       61. The circuit according to  claim 57 , wherein the first filter, the one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and the last filter are selected from the group consisting of SAW filters, ceramic filters, tuned inductance/capacitance filters, and bulk acoustic wave filters. 
     
     
       62. The circuit according to  claim 50 , wherein the plurality of reflection amplifiers are connected to a bias controller arranged to control transistor currents within the amplifiers. 
     
     
       63. A method of amplifying an input signal and providing a corresponding amplified output signal, the method comprising the steps of:
   a )  a plurality of reflection amplifiers cascaded in series along a signal path and operative to amplify the input signal propagating in a forward direction therealong to provide the output signal; and        b )  connecting means for connecting the reflection amplifiers to form the signal path and for hindering signal propagation in a reverse direction therealong, thereby counteracting spontaneous oscillation from arising within the circuit, the connecting means incorporating one or more filters which are interposed between neighboring reflection amplifiers along the signal path, and modulating means for modulating the input signal to associated sideband signal components and converting to and from the associated sideband signal components along the path, the one or more filters and the modulating means being operative to promote signal propagation in the forward direction along the path and hinder signal propagation in the reverse direction therealong.     
     
     
       64. The method according to  claim 63  further comprising providing a first filter preceding the first reflection amplifier in the series along the signal path. 
     
     
       65. The method according to  claim 64  further comprising providing a last filter succeeding the last reflection amplifier in the series along the signal path. 
     
     
       66. The method according to  claim 65 , wherein the modulating means comprises a plurality of phase switches, each phase switch having a respective reflection amplifier associated therewith. 
     
     
       67. The method according to  claim 66 , wherein directing the input signal through the connecting means to one of the reflection amplifiers comprises directing the input signal through the first filter and through a first of the plurality of phase switches. 
     
     
       68. The method according to  claim 67 , wherein directing the amplified signal in the forward direction to another of the reflection amplifiers comprises directing the amplified signal back through the first of the plurality of phase switches, through one of the one or more filters, and through a second of the plurality of phase switches.