| 摘要 |
Microwave circuit comprising a low-noise amplifier with three stages, each stage of which is formed by a field-effect transistor and input and output matching circuits intended to minimise the noise factor and maximise the gain within a useful frequency band and also comprising means for filtering the noise outside this useful frequency band, characterised in that the filtering means are band-pass structures whose pass band is exactly centred on the useful frequency band of the circuit, in that the input, output and inter-stage matching networks of the amplifier consist of such a structure, and in that each stage of the amplifier participates in reducing the noise factor, in increasing the gain and in rejecting undesirable frequencies. Application: monolithic construction of a microwave reception head. <IMAGE>
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