Method and system for creating a spectral null in a switching amplifier
A method and system for creating a spectral null in a switching amplifier system is provided. The method includes receiving an input signal in a first modulated form at an input stage 104 of the amplifier. The method further includes converting the input signal to a second modulated form. The input signal in the second modulated form is referred to as a first switching signal. Further, the method includes determining switching frequency of the first switching signal from a predefined cycle time of the first switching signal. Thereafter, the method includes inverting the first switching signal and delaying it by a predefined delay amount. The inverted and delayed first switching signal is referred to as a second switching signal The method further includes summing the first switching signal from the second switching signal, which results in a two-state output signal. The two-state output signal is free of any components at the switching frequency and its odd harmonics.
1. A method for creating at least one spectral null in a switching amplifier system, the method comprising:
receiving input signal in a first modulated form;
converting the input signal to a first switching signal, wherein the first switching signal is in a second modulated form;
determining a switch frequency from a predefined cycle time of the first switching signal;
generating a second switching signal from the first switching signal, the second switching signal being inverted and delayed by a delay amount as compared to the first switching signal; and
summing the first switching signal with the second switching signal to provide only a two-state output signal in order to create the at least one spectral null.
2. The method of claim 1 further comprising prorating the input signal by a first predefined constant.
3. The method of claim 1 further comprising applying an offset to the first switching signal and the second switching signal by respectively adding and subtracting a second predefined constant.
4. The method of claim 1 further comprising removing the offset by prorating the output signal by inverse of a first predefined constant.
5. The method of claim 1 , wherein pulse width of the second switching signal is the same as that of a corresponding pulse of the first switching signal.
6. The method of claim 1 , wherein the second modulated form can be at least one of pulse width modulation (PWM) form and pulse density modulation (PDM) form.
7. The method of claim 6 , wherein each of the first switching signal and the second switching signal is of a signal type selected from a group consisting of a PWM signal and a PDM signal.
8. The method of claim 7 , wherein each of the first switching signal and the second switching signal is at least one of a single sided and a double sided PWM signal.
9. A circuitry for creating at least one spectral null in a switching amplifier system, the circuitry comprising:
an input module that receives an input signal in a first modulation form;
a modulation conversion circuitry coupled to the input for modulating the input signal and generating a first switching signal from the input signal;
a frequency determining circuitry for determining a switching frequency of the first switching signal;
an inverting delay circuitry coupled to the modulation conversion circuitry for generating a second switching signal from the first switching signal, the second switching signal being inverted and delayed by a delay amount as compared to the first switching signal; and
a summing circuitry for summing the first switching signal from the second switching signal to provide only a two-state output signal in order to create the at least one spectral null.
10. The circuitry of claim 9 further comprising a prorating circuitry for prorating the input signal by a first predefined constant.
11. The circuitry of claim 9 , wherein the modulation conversion circuitry comprises at least one of pulse width modulation (PWM) and pulse density modulation (PDM) circuitry.
12. The circuitry of claim 11 , wherein each of the first switching signal and the second switching signal is of a signal type selected from a group consisting of a PWM signal and a PDM signal.
13. The circuitry of claim 11 , wherein each of the first switching signal and the second switching signal is a two sided PWM signal.
14. The circuitry of claim 9 , wherein the pulse width of the second switching signal is the same as that of a corresponding pulse of the first switching signal.