Suppression in Active Devices-Circuits. Volume III. Noise in Gunn Effect Devices.
Abstract
Measurements of the FM noise of CW X-band Gunn oscillators indicate that two noise sources must be considered in developing an oscillator noise model. One source is the thermal noise in the vicinity of the carrier frequency, which may be generated by hot electrons in the high field domain. The second source is low frequency flicker (1/f) noise current, which is thought to be generated by traps associated with impurity states. An expression for the FM noise deviation caused by a thermal noise source has been derived by Edson. This component of a Gunn diode's FM noise is white (i.e., constant with frequency from the carrier). The author has calculated the flicker noise sources' contribution by considering it as a small signal frequency modulation. The FM noise produced by this source falls roughly as 1/f with frequency from the carrier. Since the two sources are physically unrelated, their noise spectra are uncorrelated and will add as mean squares. This model agrees well with measured noise spectra. Once three parameters of the model are established for a particular device, its noise performance in any circuit may be calculated from data obtained by simple microwave measurements. Typically, FM noise is below 10 Hz in a 1 KHz bandwidth to within 2 KHz of the carrier, for circuit loaded Q's between 50 and 100. A high loaded Q (approximately 1000) circuit produced FM noise below .7 Hz in a 1 KHz bandwidth at 1 MHz from the carrier. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1971
- Accession Number
- AD0883608
Entities
People
- A. Sweet
- J. Baukus
- Joe M. Ballantyne
Organizations
- Cornell University College of Engineering