Transient suppression circuit for push-pull switching amplifiers

A push-pull amplifier comprising:

• first and second switching amplifier elements operating to alternately conduct an input signal for 180.degree. intervals;
• means for phase shifting the input signals to said first switching amplifier element 180.degree. 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.

A push-pull amplifier comprising:

• first and second switching amplifier elements operating to alternately conduct an input signal for 180.degree. intervals;
• means for phase shifting the input signals to said first switching amplifier element 180.degree. 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.