Jeffrey Morris Keefer

Title: The Innovations of Jeffrey Morris Keefer

Introduction

Jeffrey Morris Keefer is a notable inventor based in San Diego, CA. He has made significant contributions to the field of microwave synthesizers, particularly with his innovative designs that enhance frequency-hopping capabilities. His work is characterized by a focus on efficiency and performance in electronic systems.

Latest Patents

Keefer holds a patent for a "Numerically-controlled nyquist-boundary hopping frequency synthesizer." This invention is an inexpensive numerically-controlled fast frequency-hopping microwave synthesizer. The synthesizer's design allows a voltage-controlled oscillator (VCO) output phase to remain locked to an internal direct digital synthesizer (DDS) reference signal over a wide output frequency band. This band is significantly larger than the internal sampling clock frequency. The "Nyquist-boundary hopping" scheme compares signals from an alias band of the DDS with signals from an alias band of the sampled VCO output. This comparison derives an output phase error signal, which is forced to zero, effectively locking the VCO output phase to the DDS output phase over a frequency hop-distance greater than the DDS bandwidth. The synthesizer can hop phase-continuously in a single clock cycle to each of hundreds of thousands of different microwave output frequencies within a second, utilizing relatively low clock rates of up to 100 MHz. This capability is particularly advantageous for silicon application-specific integrated circuits (ASICs). Additional features enhance the synthesizer's performance, including a digital "whitening" filter, a digital VCO control linearization loop, a digital cyclic error removal loop, and a Sigma-Delta quantizer.

Career Highlights

Keefer is currently employed at Cubic Defense Systems, Inc., where he continues to innovate and develop advanced technologies. His work at Cubic Defense Systems has allowed him to apply his expertise in frequency synthesis to various defense applications.

Collaborations

One of Keefer's notable collaborators is Wayne Edward Richards. Their partnership has contributed to the advancement of technologies in their field.

Conclusion

Jeffrey Morris Keefer's contributions to microwave synthesizer technology exemplify the impact of innovative thinking in engineering. His patent for a numerically-controlled frequency synthesizer showcases his ability to solve complex problems in electronic design. Keefer's work continues to influence advancements in the field, demonstrating the importance of innovation in technology.