- What:
- The portion of the radio spectrum over which the transistor has useful performance (as an amplifier). A common definition of "useful" is greater than 6 dB of gain.
- Amplifier performance varies with frequency. Many gainblocks (INAs, most MSAs) have a gain vs. frequency characteristic that exhibits constant (or small signal) gain from very low frequencies up to some corner frequency and then begins to "roll off" or decrease. f3dB is the frequency at which the gain has decreased 3 dB from the small signal gain level.
- Amplifiers with minimal feedback (MSA-08, 99) will lack the "flat gain" region. For these products it is more useful to quote gain performance at specific frequencies.
- GaAs based amplifiers (MGAs) typically have a low frequency roll-off as well as a high frequency roll-off. In this case the useful frequency range is quoted as a bandwidth (BW). Certain MSAs (MSA-05,09,10,11) use DC blocked feedback resistors and have a low frequency corner around 50 MHz below which match deteriorates and gain increases. Tuned amplifiers (HPMX-3002) will also typically be quoted as operating over a specific bandwidth.
- Direction:
- needs to be sufficient to meet application, but not excessive. Too much gain can result in distortion from early saturation.
- Range:
- kHz to 10 GHz (RF/uw)
- kHz to 50 GHz (mmw)
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