Microwave transistor amplifier
AssigneeCommunications Satellite Corporation (Comsat)
InventorRonald E. Stegens
Life of this patent
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Abstract
A low noise, multistage microwave transistor amplifier constructed using microwave integrated circuit techniques is disclosed. The illustrated embodiment is a two-stage transistor amplifier which is the basic building block for broadband, high-gain cascades. This amplifier features an interstage network consisting of a very short transmission line which minimizes the size and frequency dependence of the amplifier. This is achieved in the satellite communications band of 3.7 to 4.2 GHz by constructing the amplifier on a suitably low dielectric constant substrate rather than the usual high dielectric constant substrates used in microwave amplifier applications.
Claims7
A broadband, low noise microwave transistor amplifier comprising:
- a first bipolar transistor connected as a first common emitter amplifier stage,
- an input distributed parameter impedance matching network connected to the base of said first transistor and having a source admittance selected to minimize the noise measure, M, of said first transistor defined by the equation ##EQU20## where F is the noise figure and G is the gain, a second bipolar transistor connected as a second common emitter amplifier stage,
- an interstage distributed parameter impedance matching network connected to the base of said second transistor and producing a second stage source admittance selected to minimize the noise measure, M, of said second transistor over at least a part of the amplifier bandwidth while yielding a net constant gain for the composite two stage amplifier,
- said interstage network connecting the collector of said first transistor to the base of said second transistor and consisting of a short transmission line, and
- an output matching network connected to the collector of said second transistor which produces a constant output impedance over a broad frequency range.
Dependencies are inferred from the claim text.