Apparatus and method for paralleling power field effect transistors in high frequency amplifiers

Claim 2

Apparatus for providing a constant duty cycle rectangular wave signal in response to an input sine wave signal over the 1.6 MHz to 30 MHz frequency range and above, comprising: wave shaping means for converting said input sine wave signal into a square wave signal, said square wave signal having a same frequency as said input sine wave signal; voltage means coupled to said wave shaping means for providing a voltage signal having an amplitude determined by said square wave signal frequency; integrator circuit means for providing a triangular wave signal in response to said square wave signal, triangular wave signal having a slope determined by said voltage signal amplitude; and comparator means for controlling a duty cycle of said rectangular wave signal in response to said triangular wave signal.

Claim 3

The apparatus for providing a constant duty cycle rectangular wave signal of claim 1 wherein said integrator circuit means includes an amplifier circuit with a voltage-controlled capacitor coupled in a feedback circuit of said amplifiers.

Claim 4

The apparatus for providing a constant duty cycle rectangular wave signal of claim 2 wherein said voltage-controlled capacitor coupled in said feedback circuit has a capacitance determined by said voltage signal amplitude.

Claim 5

The apparatus for providing a constant duty cycle rectangular wave signal of claim 3 wherein said voltage means includes a monostable multivibrator.

Claim 6

The apparatus for providing a constant duty cycle rectangular wave signal of claim 4 wherein said voltage means includes a second amplifier circuit coupled to said monostable multivibrator, said second amplifier circuit having a feedback circuit with a capacitor and a resistor coupled in parallel, wherein an output terminal of said amplifier circuit coupled to said voltage-controlled capacitor.

Claim 7

The apparatus for providing a constant duty cycle rectangular wave of claim 5 wherein said second amplifier circuit has Zener diode and a resistor coupled in series with said Zener diode coupled in parallel with said feedback circuit.

Claim 8

The apparatus for providing a constant duty cycle rectangular wave signal of claim 5 further comprising second comparator means responsive to said triangular wave signal for controlling a negative portion of said rectangular wave signal.

Claim 9

The apparatus for providing a constant duty cycle rectangular wave signal of claim 7 wherein further comprising a network means coupled to a second terminal of said comparator means and a second terminal of said second comparator means, said network means controlling said rectangular wave duty cycle and rectangular wave symmetry.

Claim 10

The apparatus for providing a constant duty cycle rectangular signal of claim 8 wherein said wave shaping means includes a diode clipping circuit and a plurality of amplifiers.

Claim 11

The apparatus for providing a constant duty cycle rectangular wave of claim 9 wherein said triangular wave slope is substantially proportional to said sine wave frequency.

Claim 14

The method for providing a constant duty cycle rectangular wave signal of claim 11 wherein said using step includes the step of coupling said voltage controlled capacitor in a feedback path of an amplifier.

Claim 15

The method for providing a constant duty cycle rectangular wave signal of claim 12 further comprising the step of generating said triangular wave signal in response to said square wave signal, said triangular wave signal having a same frequency as said square wave signal.

Claim 16

The method of providing a constant duty cycle rectangular wave signal of claim 13 further comprising the step of selecting component values to provide a slope of said triangular wave signal that is substantially proportional to said sine wave frequency.

Claim 17

A switching amplifier for use in a Class D, Class E, Class F and Class S modes of operation, said switching amplifier capable of operation in the frequency range of 1.6 MHz to 30 MHz and above, said switching amplifier comprising: a signal processing unit for providing a constant duty rectangular wave output signal in response to a sine wave input signal, wherein said signal processing unit comprises; square wave means for providing a square wave signal in response to said sine wave signal, said square wave signal and said sine wave signal having the same frequency, triangle wave signal means for providing a triangle wave signal in response to said square wave signal, a slope of said triangle wave determined by said square wave signal frequency, and comparator means for controlling said rectangular wave in response to said triangular wave signal; a power amplifier responsive to said rectangular wave signal for amplifying said rectangular wave signal; and voltage source means for supplying power to said power amplifier, said voltage means responsive to said sine wave input signal for modulating a voltage supplied to said amplifier.

Claim 18

A switching amplifier for use in a Class D, Class E, Class F and Class S modes of operation, said switching amplifier capable of operation in the frequency range of 1.6 MHz to 30 MHz and above, said switching amplifier comprising: a signal processing unit for providing a constant duty rectangular wave output signal in response to a sine wave input signal, wherein said signal processing unit comprises; square wave means for providing a square wave signal in response to said sine wave signal, said square wave signal and said sine wave signal having the same frequency, triangle wave signal means for providing a triangle wave signal in response to said square wave signal, a slope of said triangle wave determined by said square wave signal frequency, and comparator means for controlling said rectangular wave in response to said triangular wave signal; a power amplifier responsive to said rectangular wave signal for amplifying said rectangular wave signal; and voltage source means for supplying power to said power amplifier, said voltage means responsive to said sine wave input signal for modulating a voltage supplied to said amplifier.

Claim 19

The switching amplifier of claim 15 wherein said power amplifier includes a positive rectangular wave signal amplifier and a negative rectangular wave signal amplifier, said switching amplifier further comprising a combining network for combining an amplified signal from said positive rectangular wave signal amplifier and an amplified signal from said negative rectangular wave amplifier.

Claim 20

The switching amplifier of claim 16 wherein said signal processing unit includes modulation means for applying a modulation signal modulating said input sine wave signal to said voltage source means.

Claim 21

The switching amplifier of claim 17 wherein triangular wave means includes; a frequency to voltage converter providing a voltage signal having an amplitude determined by said square wave frequency, and an integrator circuit having a voltage controlled capacitor in a feedback circuit, a capacitance of said voltage controlled capacitor determined by said voltage signal.

Claim 22

The switching amplifier of claim 18 wherein said signal processing unit further includes network means for controlling said rectangular wave duty cycle and a symmetry begin positive and negative portions of said rectangular wave.