Experience

Design and Development

Dr. Weaver has over 30 years of design and development experience in the fields of power electronics, analog and RF power systems serving the military, industrial, scientific and medical industries. Representative examples of his design and development experience include:

• Analog Audio Processor for radio station loudness control. (Designed)
• High Voltage Pulse Width Modulator which utilized a power tetrode and solid-state diode array in a buck configuration for use in 250 kW and 500 kW shortwave transmitters. (Designed, Developed)
• Solid-State Modulator utilizing all solid-state medium voltage series connected power switches for use in AM medium wave and shortwave transmitters ranging from 100 kW to 600 kW. (Designed, Developed)
• 600 kW AM medium wave transmitter which utilized a solid-state modulator, RF driver and a single tetrode RF power amplifier. (Designed, Developed)
• 42 MHz RF power amplifier for use in a 1.0 Tesla MRI power amplifier. (Designed)
• Analog pre-processor and data acquisition hardware for a naval sonar system. (Designed, Developed)
• 100 kV at 20 Amp power supply for a linear accelerator. (Designed)
• RF lead for 80 kW high power microwave project. (Developed)
• Advisor for a 40 kV high voltage power supply for 80 kW X-band transmitter. (Designed power switch assembly)
• Project engineer for a 100 kW shortwave transmitter modernization program. (Designed, Developed)
• Power electronics assembly for a 0.5 Tesla MRI RF power amplifier. (Designed, Developed)

Troubleshooting and Redesign

• Identified slow driver transistors as cause of erratic shutdown of an airborne radar jamming transmitter housekeeping power supply.
• Identified transformer core saturation as cause for high voltage power supply intermittent failures.
• Improved the efficiency of a fire alarm panel power supply with power factor correction.
• Identified an over heating coaxial cable was due to sneak path of low voltage power supply return current.

Litigation Support

• Participated in prosecution activities for 5 U.S. Patents.
• Supported litigation activities to defend patented device.

Industries and Clients

• Commercial and International Broadcasting
• Product Manufacturing
• Department of Defense (through subcontractors)
• Medical Electronics
• Consumer Electronics
• Industrial Electronics
• United States National Laboratories

US Patents

US Patent 4,747,161

AM-RF Transmitter with Compensation for Power Supply Variations

This invention provides compensation for distortion that is caused by DC supply voltage variations in amplitude modulated, radio frequency transmitters. These variations are usually caused by a combination of line voltage fluctuations, power supply hum and a resonance of the HV transformer leakage reactance and the filter capacitance which is excited by low frequency modulation. Read More…

US Patent 4,776,036

RF-AM Transmitter with Pulse Width Modulator

This invention provides compensation for pulse width stretching which can occur in high voltage pulse width modulated power amplifiers during short pulse width conditions. The increase in pulse area that results from pulse width stretching is corrected by reducing the amplitude of only short duration pulses applied to the power amplifier. Read More…

US Patent 4,896,372

Pulse Width Modulator for AM-RF Transmitter

This invention provides for increasing the overall efficiency of a pulse width modulated power amplifier. The pulse width modulated waveform must have a relatively high switching frequency to faithfully reproduce simultaneously occurring high frequency, high amplitude modulation. Since high frequency, high amplitude signals seldom occur simultaneously, the constantly high switching frequency results in unnecessarily high switching losses. To provide low overall switching loss and good high frequency high amplitude reproduction, the switching frequency is a function of the frequency and amplitude of the modulation signal. Read More…

US Patent 5,099,203

Power Amplifier Having Multiple Switched Stages and Method of Operating Same

This invention provides for further improving the overall efficiency of a pulse width modulated power amplifier by reducing both switching and conduction losses. Multiple stages are used for selectively coupling power from a DC power supply to the load. The use of multiple stages reduces the voltage across the switching amplifier and therefore switching losses by approximately the number of stages that are utilized. In addition, reducing the voltage across the switching element allows for replacing a single vacuum tube power switch with multiple transistor power switches allowing for the reduction in conduction losses. Read More…

US Patent 5,200,707

Amplifier with Multiple Switched Stages and Noise Suppression

This invention provides compensation for distortion that is caused by DC supply voltage variations in amplitude modulated, radio frequency transmitters using a multiple-switch modulator. The multiple switching stages which are controlled in response to the modulating signal, are also controlled by DC supply voltage variations that change the threshold levels which are used to select how many switched sources are enabled. Read More…