Feedback controller for PWM amplifier
First Claim
1. A feedback controller for a PWM amplifier, the controller comprising:
- a signal input for receiving a pulse width modulated (PWM) input signal whose duty cycle represents a desired analogue output signal;
a feedback input for receiving a feedback signal representing an actual PWM output signal of the amplifier;
means for generating a filtered error signal comprising a filtered representation of differences between the input signal and the feedback signal;
means for comparing the filtered error signal with a reference to generate a provisional PWM switching control signal for controlling the PWM amplifier; and
a pulse conditioner comprising a sequential logic circuit arranged to receive both the provisional PWM switching control signal and the PWM input signal for outputting to the amplifier a conditioned PWM switching control signal comprising the provisional PWM switching control signal modified so as to inhibit a transition in the switching control signal under conditions defined by reference to past transitions in the PWM input signal.
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Accused Products
Abstract
A feedback controller in a PWM amplifier comprises a signal input for receiving a pulse width modulated (PWM) input signal (Vin) whose duty cycle represents a desired analogue output signal. A feedback loop filter 518 generates a filtered error signal (Vint) comprising a filtered representation of differences between the input signal (Vin) and a feedback signal (Vfb). A comparator (520) compares the filtered error signal with a reference to generate a provisional PWM switching control signal (C) for controlling the PWM amplifier (500). A pulse conditioner (532) receives both the provisional PWM switching control signal (C) and the PWM input signal (X=Vin) and outputs to the amplifier (500) a conditioned PWM switching control signal (Y), modified in accordance with predetermined constraints in relation to the PWM input signal. The pulse conditioner includes a single pulse function (534) whereby only a single pulse is permitted for every pulse in the input signal, thereby eliminating oscillations that can otherwise Occur under over-voltage supply conditions. Missing pulse and minimum pulse width functions (536, 538) can also be provided.
46 Citations
30 Claims
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1. A feedback controller for a PWM amplifier, the controller comprising:
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a signal input for receiving a pulse width modulated (PWM) input signal whose duty cycle represents a desired analogue output signal; a feedback input for receiving a feedback signal representing an actual PWM output signal of the amplifier; means for generating a filtered error signal comprising a filtered representation of differences between the input signal and the feedback signal; means for comparing the filtered error signal with a reference to generate a provisional PWM switching control signal for controlling the PWM amplifier; and a pulse conditioner comprising a sequential logic circuit arranged to receive both the provisional PWM switching control signal and the PWM input signal for outputting to the amplifier a conditioned PWM switching control signal comprising the provisional PWM switching control signal modified so as to inhibit a transition in the switching control signal under conditions defined by reference to past transitions in the PWM input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 18, 19, 20)
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11. A feedback controller for a PWM amplifier, the controller comprising:
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a signal input for receiving a pulse width modulated (PWM) input signal whose duty cycle represents a desired analogue output signal; a feedback input for receiving a feedback signal representing an actual PWM output signal of the amplifier; a feedback loop filter for generating a filtered error signal comprising a filtered representation of differences between the input signal and the feedback signal; a comparator for comparing the filtered error signal with a reference to generate a provisional PWM switching control signal for controlling the PWM amplifier; and a pulse conditioner comprising a sequential logic circuit arranged to receive both the provisional PWM switching control signal and the PWM input signal for outputting to the amplifier a conditioned PWM switching control signal comprising the provisional PWM switching control signal modified to inhibit a transition in the switching control signal under conditions defined by reference to past transitions in the PWM input signal. - View Dependent Claims (12, 13, 14)
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21. A method of controlling a PWM amplifier, the method comprising:
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receiving a pulse width modulated (PWM) input signal whose duty cycle represents a desired analogue output signal; receiving a feedback signal representing an actual PWM output signal of the amplifier; generating a filtered error signal comprising a filtered representation of differences between the input signal and the feedback signal; comparing the filtered error signal with a reference to generate a provisional PWM switching control signal for controlling the PWM amplifier; and outputting to the amplifier a conditioned PWM switching control signal comprising the provisional PWM switching signal modified to inhibit a transition in the switching control signal under conditions defined by reference to past transitions in the PWM input signal. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification