Cross current minimization
AssigneeST-Ericsson SA
InventorNedialko Slavov
Life of this patent
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Abstract
A method of optimising cross current in class D amplifiers and simultaneously minimizing the harmonic distortion is provided. The method overcomes the problem of using the limited speed voltage comparators often used in cross current preventing circuits. Method embodiments are based on introducing a replica amplifier with a current sensor matched to a main amplifier. The duration of a sensed cross current within the replica amplifier is compared by a current comparator with a small enough reference current. The comparator output generates a pulse with a duration equal to the duration of the cross current event in the replica amplifier. The duration of that pulse is measured and used to generate a dead time pulse for blanking amplifier pre-driver inputs.
Claims17
1-15. (canceled)
A method for minimizing cross current in an amplifier comprising switches, the amplifier being coupled to a replica amplifier comprising a current sensor, the amplifier being further coupled to a current comparator, the method comprising:
- extracting, by the current sensor, an image of a replica cross current;
- comparing, by the comparator, the replica cross current image to a reference current;
- creating, by the comparator, a first pulse having a duration substantially equal to a replica cross current duration sensed by the current sensor, the first pulse being adapted to enable generation of a second pulse comprising a second pulse duration substantially equal to the replica cross current duration;
- providing the second pulse of the amplifier, the second pulse adapted to prevent at least some of the switches from switching ON during the pulse duration of the second pulse in order to minimize the cross current in the amplifier.
A module arranged to minimize cross current in an amplifier comprising switches, the module further comprising:
- a replica amplifier comprising:
- a current sensor adapted to extract an image of a replica cross current in the replica amplifier;
- and
- a comparator adapted to compare the image of the replica cross current to a reference current, and adapted to create a first pulse having a duration substantially equal to a replica cross current duration sensed by the current sensor, the first pulse being adapted to enable generation of at least one second pulse provided to the amplifier and adapted to prevent, during the second pulse, at least some of the switches from switching ON in order to minimize a cross current in the amplifier.
Dependencies are inferred from the claim text.