Title: Class D amplifier

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Claims: What is claimed is:

1. A class D amplifier comprising:

first and second serially coupled active current conducting devices;

first and second unidirectional current conducting devices respectively parallelly coupled to said first and second active devices and poled for conducting forward current in a direction opposite to forward current conduction in said first and second active devices;

means coupling the junction of said first and second active devices to the junction of said first and second unidirectional devices for forming an output terminal adapted for supplying current to a load; and

means coupled to control electrodes of said first and second active devices for providing signals for alternately enabling said first and second active devices for conduction such that during a first portion of an amplifying cycle said first active device conducts in the forward direction and said second active device conducts in its reverse direction, and during a second portion of said amplifying cycle said second active device conducts in its forward direction and said first active device conducts in its reverse direction for minimizing crossover distortion in said amplifier.

2. A class D amplifier according to claim 1 wherein said means coupled to said control electrodes includes biasing means for maintaining forward conduction of said respective first and second unidirectional devices when the reverse current through said respective first and second active devices exceeds a predetermined amount.

3. A class D deflection amplifier comprising:

first and second serially coupled active current conducting devices;

first and second unidirectional current conducting devices respectively parallelly coupled to said first and second active devices and poled for conducting forward current in a direction opposite to forward current conduction in said first and second active devices;

means coupling the junction of said first and second active devices to the junction of said first and second unidirectional devices for forming an output terminal adapted for supplying scanning current to a deflection winding; and

means coupled to control electrodes of said first and second active devices for providing a pulse width modulated signal having a first frequency, said modulation being representative of the amplitude of a second frequency signal for alternately enabling said first and second active devices for conduction such that during a first portion of said second frequency signal said first active device conducts in the forward direction and said second active device and said second unidirectional device conduct in their reverse and forward directions, respectively, and during a second portion of said second frequency signal said second active device conducts in its forward direction and said first active device and said first unidirectional device conduct in their reverse and forward directions, respectively.

4. A class D deflection amplifier according to claim 3 wherein said first and second active devices comprise first and second transistors having their main conduction paths coupled for forming a push-pull amplifier configuration, said first frequency signal is a signal at a multiple including one of the horizontal deflection rate and said second frequency signal is at the vertical deflection rate.

5. A class D deflection amplifier according to claim 4 wherein said vertical deflection rate signal comprises a sawtooth waveform for effecting modulation of said horizontal rate signals coupled to said push-pull amplifier such that the average current obtained from said output terminal comprises a sawtooth current waveform at the vertical deflection rate for application to said deflection winding.

6. A class D deflection amplifier comprising:

first and second active current conducting devices serially coupled between first and second terminals of a source of operating current;

first and second unidirectional current conducting devices each coupled to a junction of said first and second active current conducting devices and each coupled to a respective one of said first and second terminals of said source of current, said first and second unidirectional devices respectively being poled for conducting current in their forward direction in directions opposite to the forward current paths of said first and second active devices, respectively, said junction forming an output terminal adapted to supply scanning current to a deflection winding;

a source of first signals having a first frequency;

a source of second signals having a second frequency;

modulating means coupled to said source of first and second signals for pulse width modulating said first signals in accordance with the amplitude of said second signals, said modulating means being coupled to control electrodes of said first and second active devices for enabling conduction thereof by said pulse width modulated first signals, such that when average current is flowing in a first direction in said deflection winding said first active device conducts in its forward direction and said second active device and said second unidirectional device conduct in their reverse and forward directions, respectively, and when average current is flowing in the opposite direction in said deflection winding said second active device conducts in its forward direction and said first active device and said first unidirectional device conduct in their reverse and forward directions, respectively.

7. A class D deflection amplifier according to claim 6 wherein said first signals comprise signals at a multiple including one of the horizontal deflection rate and said second signals comprise sawtooth signals at the vertical deflection rate.
Other info:

Inventors: Peer, John Charles (Indianapolis, IN, US)

Application Number: 444405
Filing Date: 1974-02-21
Publication_date: 1976-02-17
Assignee: RCA Corporation (New York, NY)
Primary Class(es): 315/397 315/387, 315/407, 330/207A, 330/251
Other Classes:
US Patent Ref:

3015781	Jan, 1962	Eklov	330/207.
3336538	Aug, 1967	Crowhurst	330/207.
3548329	Dec, 1970	Camenzind	330/207.
3636380	Jan, 1972	Anderson	330/13.
3781589	Dec, 1973	Brockmann	315/397.

Other Refs:
Primary Examiner: Tubbesing, T. H.
Assistant Examiner: Blum, T. M.
Attorney: Whitacre; Eugene M., Rasmussen; Paul J.