Method and device for generating PWM signals
AssigneeEtel S.A.
InventorClaude Froidevaux
Life of this patent
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Abstract
A PWM signal for driving power transistors of a half-bridge of a converter is generated with the aid of a digital circuit, in which an internal reference value is compared to the counter content of a counting ramp. In this context, a logic state of the PWM signal depends upon whether the internal reference value is greater than the counter content of the counting ramp. After each comparison between the internal reference value and the counter content, an n-bit long data word dependent on the result of this comparison is output serially as PWM signal, n being greater than or equal to 2. The resolution of the PWM signal is thereby improved by the factor n in comparison to conventional systems, without markedly increasing the circuit expenditure.
Claims9
A method for generating a PWM signal with the aid of a digital circuit to drive power transistors of a half-bridge of a converter, comprising:
- comparing an internal reference value to a counter value of a counting ramp, a logic state of the PWM signal being dependent upon whether the internal reference value is greater than the counter value of the counting ramp;
- and
- after each comparison between the internal reference value and the counter value, serially outputting as the PWM signal an n-bit long data word dependent on the result of the comparison, n being greater than or equal to 2;
- wherein the internal reference value is derived from an external reference value, the internal reference value being an integer component of a quotient of the external reference value and n.
The method according to claim herein the data word is made up exclusively of bits of a first logic value, if the counter value is smaller than the internal reference value.
A device for generating a PWM signal with the aid of a digital circuit in order to drive power transistors of a half-bridge of a converter, comprising:
- a comparison device adapted to compare an internal reference value to a counter value of a counting ramp, a logic state of the PWM signal being dependent upon whether the internal reference value is greater than the counter value of the counting ramp;
- and
- a serializer-type converter adapted to serially output, after each comparison between the internal reference value and the counter value, an n-bit long data word dependent on a result of the comparison as the PWM signal, n being greater than or equal to 2;
- wherein the internal reference value is derived from an external reference value, the internal reference value being an integer component of a quotient of the external reference value and n.
Dependencies are inferred from the claim text.