  Radio telescope front ends must have simultaneously low noise and
sufficiently-high linearity to accommodate interfering signals. Typically these
are opposing design goals. For modern radio telescopes operating in the HF
(3-30 MHz) and VHF-low (30-88 MHz) bands, the problem is more nuanced in that
front end noise temperature may be a relatively small component of the system
temperature, and increased linearity may be required due to the particular
interference problems associated with this spectrum. In this paper we present
an analysis of the sensitivity-linearity trade off at these frequencies,
applicable to existing commercially-available monolithic microwave integrated
circuit (MMIC) amplifiers in single-ended, differential, and parallelized
configurations. This analysis and associated findings should be useful in the
design and upgrade of front ends for low frequency radio telescopes. The
analysis is demonstrated explicitly for one of the better-performing amplifiers
encountered in this study, the Mini-Circuits PGA-103, and is confirmed by
hardware measurements. We also present a design based on the Mini-Circuits
HELA-10 amplifier, which is better-suited for applications where linearity is a
primary concern.
