Transient suppression circuit for push-pull switching amplifiers

Claim 2

A push-pull amplifier comprising: first and second switching amplifier elements operating to alternately conduct an input signal for 180° intervals, means for phase shifting the input signals to said first switching amplifier element 180° relative to the input signal of said second switching amplifier element, an output transformer having a primary coil with first and second end terminals located at respective ends of the coil and a grounded center tap, said first end terminal being coupled to the output of said first switching amplifier element, said second end terminal being coupled to the output of said second switching amplifier element, and a secondary coil connected to a load, A d.c. power source; and protective coupling means connecting said D.C. power source to said first and second end terminals of said primary coil and the outputs of the first and second switching amplifier elements, said protective coupling means limiting the voltage level of said primary coil switching amplifier elements to inhibit high transient voltages caused during conductive switching of said amplifier elements.

Claim 3

A push-pull amplifier as set forth in claim 1 wherein said protective coupling means comprises: a power supply filter comprising a filter capacitor and an inductor coil with first and second end terminals, the center tap of said inductor coil connected to said D.C. power source, said first end terminals of the inductor coil coupled to said first end terminals of said output transformer primary coil and the output of said first switching amplifier element, said second end terminal of the inductor coil coupled to said second end terminal of said output transformer primary coil and the output of said second switching amplifier element, and said filter capacitor coupled between the inductor coil center tap and ground.

Claim 4

A push-pull amplifier as set forth in claim 2 wherein said protective coupling means further includes a first feedback diode having its cathode coupled to the inductor coil center tap and its anode coupled between the first end terminal of said output transformer primary coil and said first end terminal of said inductor coil, and a second feedback diode having its cathod coupled to said inductor coil center tap and its anode coupled between said second end terminal of said output transformer primary coil and said second end terminal of said inductor coil, whereby transient currents caused during switching of said switching amplifier elements will feedback from said output transformer primary coil to said power supply filter.

Claim 5

A push-pull amplifier as set forth in claim 3 wherein said first and second feedback diodes limit the voltage across each half of the primary coil of said output transformer to substantially the voltage of said D.C. power source.

Claim 6

A push-pull amplifier as set forth in claim 3 wherein said protective coupling means further includes a first capacitor coupled between the anode of said first feedback diode and said first end terminal of said inductor coil, and a second capacitor coupled between the cathode of said second feedback diode and said second end terminal of said inductor coil, whereby the maximum voltage across said first and second switching amplifier elements is limited.

Claim 7

A push-pull amplifier as set forth in claim 5 wherein said first and second capacitors, said first and second feedback diodes, and said inductor coil limit the voltage across said first and second switching amplifier elements to approximately twice the voltage of said D.C. power source.

Claim 8

A push-pull amplifier as set forth in claim 3 wherein said first and second switching amplifier elements each include a diode coupled by its cathode to the switching amplifier element output and by its anode to ground.

Claim 9

A push-pull amplifier as set forth in claim 2 wherein the inductor coil is an auxiliary winding wound adjacent to the primary coil on the core of said output transformer.

Claim 10

A push-pull amplifier as set forth in claim 8 wherein said protective coupling means further includes a first feedback diode having its cathode connected to the inductor coil center tap and its anode connected between said first end terminal of said output transformer primary coil and said first end terminal of said inductor coil, and a second feedback diode having its cathode connected to said inductor coil center tap and its anode connected between said second end terminal of said output transformer primary coil and said second end terminal of the inductor coil, whereby transient currents caused during switching of said first and second switching amplifier elements will be fed back from said output transformer primary coil to said power supply filter.

Claim 11

A push-pull amplifier as set forth in claim 9 wherein said first and second feedback diodes limit the voltage across said output transformer one-half primary coil to the voltage of said D.C. power source.

Claim 12

A push-pull amplifier as set forth in claim 9 wherein said protective coupling means further includes a first capacitor connected between the anode of said first feedback diode and said first end terminal of said inductor coil, and a second capacitor connected between the anode of said second feedback diode and said second end terminal of said inductor coil, whereby the maximum voltage across the switching amplifier element is limited.

Claim 13

A push-pull amplifier as set forth in claim 11 wherein the first and second capacitors limit the voltage across said first and second switching amplifier elements to approximately twice the voltage of said D.C. power source.

Claim 14

A push-pull amplifier as set forth in claim 8 wherein said output transformer primary coil is wound with a smaller conductor than said inductor coil conductor.

Claim 15

A push-pull amplifier as set forth in claim 8 wherein said inductor coil has the same number of winding turns as the primary coil.

Claim 16

A push-pull amplifier comprising: first and second switching amplifier elements operating to alternately conduct an input signal for 180° intervals; means for phase shifting the input signals to said first switching amplifier element 180° relative to the input signal of said second switching amplifier element; an output transformer having a primary coil with first and second end terminals located at respective ends of the coil and a grounded center tap, said first end terminal being coupled to the output of said first switching amplifier element, said second end terminal being coupled to the output of said second switching amplifier element, and a secondary coil connected to a load; a D.C. power source; and protective coupling means connecting said D.C. power source to said first and second end terminals of said primary coil and the outputs of the first and second switching amplifier elements, said protective coupling means comprising a first feedback diode having its cathode coupled to said D.C. power source and its anode coupled to the first end terminal of said output transformer primary coil and to the output of said first switching amplifier element, and a second feedback diode having its cathode coupled to said D.C. power source and its anode coupled to the second end terminal of said output transformer primary coil and to the output of said second switching amplifier element whereby transient currents caused during switching of said switching amplifier elements will feedback from said output transformer primary coil to said D.C. power source thereby inhibiting high transient voltages caused during conductive switching of said amplifier elements.

Claim 17

A push-pull amplifier comprising: first and second switching amplifier elements operating to alternately conduct an input signal for 180° intervals; means for phase shifting the input signals to said first switching amplifier element 180° relative to the input signal of said second switching amplifier element; an output transformer having a primary coil with first and second end terminals located at respective ends of the coil and a grounded center tap, said first end terminal being coupled to the output of said first switching amplifier element, said second end terminal being coupled to the output of said second switching amplifier element, and a secondary coil connected to a load; a D.C. power source; and protective coupling means connecting said D.C. power source to said first and second end terminals of said primary coil and the outputs of the first and second switching amplifier elements, said protective coupling means comprising a first feedback diode having its cathode coupled to said D.C. power source and its anode coupled to the first end terminal of said output transformer primary coil and to the output of said first switching amplifier element, and a second feedback diode having its cathode coupled to said D.C. power source and its anode coupled to the second end terminal of said output transformer primary coil and to the output of said second switching amplifier element whereby transient currents caused during switching of said switching amplifier elements will feedback from said output transformer primary coil to said D.C. power source thereby inhibiting high transient voltages caused during conductive switching of said amplifier elements.

Claim 18

A push-pull amplifier comprising: first and second switching amplifier elements operating to alternately conduct an input signal for 180° intervals; means for phase shifting the input signals to said first switching amplifier element 180° relative to the input signal of said second switching amplifier element; an output transformer having a primary coil with first and second end terminals located at respective ends of the coil and a grounded center tap, said first end terminal being coupled to the output of said first switching amplifier element, said second end terminal being coupled to the output of said second switching amplifier element, and a secondary coil connected to a load; a D.C. power source, and protective coupling means connecting said D.C. power source to said first and second end terminals of said primary coil and the outputs of the first and second switching amplifier elements, said protective coupling means comprising: an inductor coil wound on the core of said output transformer adjacent to the primary coil having a center tap connected to said D.C. power source; a first feedback diode having its cathode coupled to the inductor coil center tap and D.C. power source and its anode coupled to the first end terminal of said output transformer primary coil and said first end terminal of said inductor coil; and a second feedback diode having its cathode coupled to the inductor coil center tap and D.C. power source and its anode coupled to the second end terminal of said output transformer primary coil and said second end terminal of said inductor coil, whereby transient currents caused during switching of said switching amplifier elements will feedback from said output transformer primary coil to said D.C. power source thereby inhibiting high transient voltages caused during conductive switching of said amplifier elements.

Claim 19

A push-pull amplifier comprising: first and second switching amplifier elements operating to alternately conduct an input signal for 180° intervals; means for phase shifting the input signals to said first switching amplifier element 180° relative to the input signal of said second switching amplifier element; an output transformer having a primary coil with first and second end terminals located at respective ends of the coil and a grounded center tap, said first end terminal being coupled to the output of said first switching amplifier element, said second end terminal being coupled to the output of said second switching amplifier element, and a secondary coil connected to a load; a D.C. power source, and protective coupling means connecting said D.C. power source to said first and second end terminals of said primary coil and the outputs of the first and second switching amplifier elements, said protective coupling means comprising: an inductor coil wound on the core of said output transformer adjacent to the primary coil having a center tap connected to said D.C. power source; a first feedback diode having its cathode coupled to the inductor coil center tap and D.C. power source and its anode coupled to the first end terminal of said output transformer primary coil and said first end terminal of said inductor coil; and a second feedback diode having its cathode coupled to the inductor coil center tap and D.C. power source and its anode coupled to the second end terminal of said output transformer primary coil and said second end terminal of said inductor coil, whereby transient currents caused during switching of said switching amplifier elements will feedback from said output transformer primary coil to said D.C. power source thereby inhibiting high transient voltages caused during conductive switching of said amplifier elements.