Feedback techniques rule GaAsFET amplifier designs
Abstract
Negative feedback effects which allow bandwidths over 10 octaves in balanced amplifier GaAs FET applications are examined analytically, along with thermal noise characteristics of GaAs FETs. S parameters are calculated for a simplified feedback equivalent circuit for an amplifier. An S-matrix is defined, and conditions under which a GaAs FET is acceptable as an amplifier are found. A curve of the FET noise with respect to the ambient temperature is provided and a relationship between the noise and temperature is formulated. The relationship is determined to be linear, indicating that low-noise amplifiers can be designed with carbonic gas, liquid N, or liquid He cooling techniques.
- Publication:
-
Microwaves
- Pub Date:
- September 1982
- Bibcode:
- 1982MicWa..21..101B
- Keywords:
-
- Amplifier Design;
- Feedback Amplifiers;
- Field Effect Transistors;
- Gallium Arsenides;
- Low Noise;
- Microwave Amplifiers;
- Cryogenics;
- Equivalent Circuits;
- Liquid Helium;
- Noise Temperature;
- Thermal Noise;
- Electronics and Electrical Engineering