Plasma particles and waves are important observation targets in space plasmas for understanding the mechanisms of energy and momentum transfer between waves and particles because space plasmas are essentially collisionless. Multi-point observations are crucial for understanding the spatial–temporal variations of space plasmas. To realize such observations by a large number of satellites, onboard instruments should be miniaturized to reduce their required resources. This paper proposes a small amplifier for plasma particle detectors onboard satellites. This charge-sensitive amplifier converts an electron cloud emitted from the detector, for example a microchannel plate, to a current pulse that can be handled by a time-of-flight measurement circuit to determine the particle velocity and thus mass. The amplifier is realized using application-specific integrated circuit technology to minimize size. Its dimensions are estimated to be $$2120\,\mathrm{ \mu m }\times 1680\,\mathrm{ \mu m}$$ 2120 μ m × 1680 μ m , which are much smaller than those of a conventional amplifier. The response time of the proposed amplifier has a variation of less than $$1.2\,\mathrm{ ns}$$ 1.2 ns over the range of expected input levels. The amplifier can handle up to $$2\times {10}^{7}$$ 2 × 10 7 signals per second and has a sensitivity of $$1.5\,\mathrm{ V}/\mathrm{pC}$$ 1.5 V / pC at $$20\,\mathrm{^\circ{\rm C} }$$ 20 ∘ C . Graphical Abstract