Communications signal amplifiers having independent power control and amplitude modulation
First Claim
1. A method of producing an amplitude modulated communications signal using an amplifier having at least one stage including a three-terminal active device having a signal input terminal, a signal output terminal, and a power supply input terminal, the method comprising:
- applying a carrier signal to the signal input terminal; and
applying a power supply input signal to the power supply input terminal, the power supply input signal being derived at least in part from an amplitude modulation signal, wherein the one stage produces the amplitude modulated communications signal in response to the carrier signal and the amplitude modulation signal, a signal level of the amplitude modulated communications signal at a given instant being proportional to a signal level of the carrier signal and to a signal level of the power supply input signal.
6 Assignments
0 Petitions
Accused Products
Abstract
The present invention, generally speaking, provides methods and apparatus for producing an amplitude modulated communications signal, in which a constant-envelope carrier signal is modified in response to a power control signal to produce a modified constant-envelope carrier signal. The modified constant-envelope carrier signal is amplified in response to an amplitude modulation signal to produce a communications signal having amplitude modulation and having an average output power proportional to a signal level of the modified constant-envelope carrier signal. This manner of operation allows wide dynamic range of average output power to be achieved. Because amplitude modulation is applied after amplitude varying circuitry used to produce the modified constant-envelope carrier signal, the amplitude modulation is unaffected by possible non-linearities of such circuitry. In accordance with another aspect of the invention, operation in the foregoing manner at comparatively low average output power levels is combined with switch mode operation at comparatively high average output power levels, enabling high overall efficiency to be achieved. Hence, the disclosed modulator and amplifier combination, in addition to supporting very low power signals, also supports high power signals.
32 Citations
47 Claims
-
1. A method of producing an amplitude modulated communications signal using an amplifier having at least one stage including a three-terminal active device having a signal input terminal, a signal output terminal, and a power supply input terminal, the method comprising:
-
applying a carrier signal to the signal input terminal; and
applying a power supply input signal to the power supply input terminal, the power supply input signal being derived at least in part from an amplitude modulation signal, wherein the one stage produces the amplitude modulated communications signal in response to the carrier signal and the amplitude modulation signal, a signal level of the amplitude modulated communications signal at a given instant being proportional to a signal level of the carrier signal and to a signal level of the power supply input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20)
-
-
12. Circuitry for producing an amplitude modulated communications signal, comprising:
-
an amplifier having at least one stage including a three-terminal active device having a signal input terminal, a signal output terminal, and a power supply input terminal;
means for generating a carrier signal, the carrier signal being applied to the signal input terminal;
means for generating a power supply input signal derived at least in part from an amplitude modulation signal, the power supply input signal being applied to the power supply input terminal;
wherein the one stage produces the amplitude modulated communications signal in response to the carrier signal and the power supply input signal, a signal level of the amplitude modulated communications signal at a given instant being proportional to a signal level of the carrier signal and to a signal level of the power supply input signal.
-
-
21. A method of producing an amplitude modulated communications signal using an amplifier having at least one stage including a three-terminal active device having a signal input terminal, a signal output terminal, and a power supply input terminal, the method comprising:
-
producing a carrier signal;
passing the carrier signal through an amplitude varying block, and controlling the amplitude varying block, taking into account any known non-linearity of the same, to produce a signal input related to a desired average power of the communications signal;
applying the signal input to the signal input terminal;
producing a power supply input signal derived at least in part from an amplitude modulation signal; and
applying the power supply input signal to the power supply input terminal, the one stage producing the amplitude modulated communications signal in response to the carrier signal and the power supply input signal;
whereby amplitude modulation is achieved independently of the amplitude varying block. - View Dependent Claims (22, 23, 24, 25, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41)
-
-
26. A communications apparatus comprising:
-
an amplitude varying circuit receiving a constant-envelope carrier signal and producing a modified constant-envelope carrier signal in response to a power control signal; and
an amplification chain including at least one stage, the amplification chain receiving the modified constant-envelope carrier signal and an amplitude modulation signal and amplifying the modified constant-envelope carrier signal to produce a communications signal having amplitude modulation and having an average output power proportional to a signal level of the modified constant-envelope carrier signal.
-
-
27. A method of producing a communications signal, comprising:
-
modifying a constant-envelope carrier signal in response to a power control signal to produce a modified constant-envelope carrier signal; and
amplifying the modified constant-envelope carrier signal in response to an amplitude modulation signal to produce a communications signal having amplitude modulation and having an average output power proportional to a signal level of the modified constant-envelope carrier signal.
-
-
28. Circuitry for producing a communications output signal having complex modulation, comprising:
-
an amplification chain having at least a final stage including a power source input and a signal input;
control paths whereby the power source input is controlled and the signal input is controlled; and
a control circuit for, through the control paths, controlling the communications output signal over a wide range of average output power levels, including;
during a first period of time, controlling the power source input level and the signal input level to be comparatively high, the final stage being operated in switch mode, thereby causing the communications output signal to have a comparatively high average power level; and
during a second period of time, modulating the power source input level and controlling the power source input level and the signal input level to be comparatively low, the final stage being operated in triode mode, thereby causing the communications output signal to have a comparatively low average power level.
-
-
36. A method of producing a communications output signal having complex modulation, using an amplification chain having at least a final stage including a power source input and a signal input, the method comprising:
-
during a first period of time, controlling the power source input level and the signal input level to be comparatively high, the final stage being operated in switch mode, thereby causing the communications output signal to have a comparatively high average power level; and
during a second period of time, modulating the power source input level and controlling the power source input level and the signal input level to be comparatively low, the final stage being operated in triode mode, thereby causing the communications output signal to have a comparatively low average power level;
whereby the communications output signal is controlled over a wide range of average output power levels.
-
-
42. A method of producing a communications output signal over a wide range of average power levels using an amplification chain having at least a final stage including a power source input and a drive signal input, comprising:
-
for a first, higher range of power levels, holding the drive signal input strength constant and modulating the power source input;
for a second, lower range of power levels, varying the drive signal input strength and modulating the power source input. - View Dependent Claims (43, 44, 45, 46, 47)
-
Specification