| 摘要 |
A wideband amplifier comprises a dual-emitter bipolar transistor arrangement with coaxial transformers, each having a high turns ratio and tight coupling between a first toroidal winding on an annular ferrite core and a second, single-turn, winding constituted by a metal container of the transformer. The second windings are coupled between respective emitters and signal ground, and the first windings are connected between the transistor base and collector, respectively, and signal ground. An input signal is supplied to the base, and an output signal is derived from the collector. The dual-emitter bipolar transistor, which has four terminals, is thereby transformed into a two-port (input port and output port) device which facilitates impedance matching, provides a linear and constant gain over a large bandwidth, provides high isolation of the input from the output, and provides low noise at the input and a high level at the output.
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