Method and apparatus for modulating a radio signal using digital amplitude and phase control signals
View Patent ↗A transmitter for modulating an RF carrier signal with an input digital data stream is disclosed. The transmitter has a processor for generating digital phase and digital amplitude signals which characterise the input digital data stream, a signal generator for generating an RF carrier signal with a phase property defined by the generated digital phase signal, an amplifier arranged to receive the RF carrier signal as an input, and a bi-level switching circuit responsive to the generated digital amplitude signal to switch between the two levels to generate a voltage signal for supplying power to the amplifier.
1. An apparatus, comprising:
a transmitter for modulating an RF carrier signal with an input digital data stream, the transmitter including
a processor for generating digital phase and digital amplitude signals which characterise the input digital data stream,
a signal generator for generating an RF carrier signal with a phase property defined by the generated digital phase signal,
an amplifier arranged to receive the RF carrier signal as an input, and
a bi-level switching circuit responsive to the generated digital amplitude signal to switch between a first fixed voltage level and a second fixed voltage level to generate a voltage signal for supplying power to the amplifier.
2. The apparatus of claim 1 wherein the switching circuit is an H-Bridge circuit.
3. The apparatus of any one of the preceding claims wherein the digital amplitude signal comprises a plurality of coded data streams for controlling the switching circuit.
4. The apparatus of claim 3 wherein the plurality of coded data streams includes a first stream for controlling charging of the amplifier and a second stream for controlling discharging of the amplifier.
5. The apparatus of claim 1 wherein the digital amplitude signal is a pulse width modulated (PWM) signal.
6. The apparatus of claim 1 wherein the generated digital amplitude signal comprises amplitude information exclusively.
7. The apparatus of claim 1 wherein the generated digital phase signal comprises phase information exclusively.
8. The apparatus of claim 1 wherein the amplifier is arranged to operate in a switched mode.
9. The apparatus of claim 1 wherein the signal generator is a frequency synthesiser.
10. The apparatus of claim 1 wherein the switching circuit comprises a reconstruction filter at its output.
11. The apparatus of claim 1 wherein the processor for generating digital phase information is a Phase Engine.
12. The apparatus of claim 1 wherein the processor for generating digital amplitude information is an Amplitude Engine.
13. The apparatus of claim 1 wherein the digital amplitude signal is MEG (Modulation Energy Gain) signal.
14. A method, comprising:
generating from a digital data stream, in a transmitter suitable for modulating an RF carrier signal with the digital data stream, a digital phase signal and a digital amplitude signal which characterise the digital data stream;
generating an RF carrier signal having a phase property defined by the digital phase signal;
passing the RF carrier signal to an RF amplifier;
causing, in response to the digital amplitude signal, a bi-level switching circuit to switch between a first fixed voltage level and a second fixed voltage level to generate a voltage supply signal; and
applying the voltage supply signal to a power supply input of the amplifier.
15. The method of claim 14 , wherein the bi-level switching circuit is an H Bridge circuit.
16. The method of claim 14 , wherein the digital amplitude signal comprises a plurality of coded data streams for controlling the bi-level switching circuit.
17. The method of claim 16 , wherein the plurality of coded data streams includes a first stream for controlling charging of the amplifier and a second stream for controlling discharging of the amplifier.
18. The method of claim 14 , wherein the amplifier is arranged to operate in a switched mode.
19. An apparatus, comprising:
a transmitter for modulating an RF carrier signal with an input digital data stream, the transmitter including
a processor for generating a digital phase signal and a digital amplitude signal which characterise the input digital data stream,
a signal generator for generating an RF carrier signal with a phase property defined by the generated digital phase signal,
an amplifier arranged to receive the RF carrier signal as an input, and
a bi-level switching circuit comprising a first fixed electrical configuration and a second fixed electrical configuration, responsive to the generated digital amplitude signal to switch between the first electrical configuration and the second electrical configuration, for generating a voltage signal, for supplying power to the amplifier, dependent upon the electrical configuration of the bi-level switching circuit.
20. A method, comprising:
generating from a digital data stream, in a transmitter suitable for modulating an RF carrier signal with the digital data stream, a digital phase signal and a digital amplitude signal which characterise the digital data stream;
generating an RF carrier signal having a phase property defined by the digital phase signal;
passing the RF carrier signal to an RF amplifier;
causing, in response to the digital amplitude signal, a bi-level switching circuit comprising a first fixed electrical configuration and a second fixed electrical configuration, to switch between the first electrical configuration and the second electrical configuration, to generate a voltage supply signal, dependent upon the electrical configuration of the bi-level switching circuit; and
applying the voltage supply signal to a power supply input of the amplifier.