These reactance-diode parametric amplifiers are designed for applications at all microwave frequencies. The heart of the line is the gallium- arsenide, variable-reactance diode, which gives improved noise performance over a wide range of temperatures. Typical models in the series include the following:
- Model S-21, an S-band amplifier, which is tunable from 2.7 to 2.9 gigacycles, and carries ratings of 3-db over-all noise figure (double sideband) with a 15-db gain over a 15-mc bandwidth;
- Model C-11, a C-band amplifier tunable from 4.4 to 5 gigacycles, with a 3-db over-all noise figure (double sideband) with 15-db gain over a 20-mc bandwidth;
- Model L-11, tunable from 0.9 to 1.2 gigacycles, with a noise figure of 1 db (double sideband) with 16-db gain over a 50-mc bandwidth. For further information, contact Texas Instruments, 6000 Lemmon Ave., Dallas, Tex. (Electronic Design, Oct. 26, 1960, p. 112)
Texas Instruments made many contributions to rf and microwave semiconductor devices and circuitry, even at the amplifier equipment level, such as these parametric amplifiers. Paramps reduced the noise figure of microwave receivers without the complexity and cost of masers. The tunnel diode was another contender for such applications, but its negative resistance characteristics were difficult to handle, and it fell out of favor among designers.
