| 摘要 |
A differential amplifier is configured in a cascode configuration that includes input transistors that are connected to corresponding cascode transistors. The gates of the cascode transistors are tied together to form a common bias for the cascode devices. The input transistors of the differential amplifier receive a differential input signal that is amplified and outputted to an output circuit that is connected to the cascode transistors. The cascode devices require a bias voltage for proper operation. Preferably, the bias voltage puts the cascode devices into the saturation region. The gates of cascode devices are coupled together and connected to a bias terminal. In embodiments of the invention, the bias terminal is connected to another terminal of the chip to provide the bias for the cascode devices. This can include the input and output nodes if they have a well-defined and relatively fixed voltage. In one embodiment, the output circuit includes a second stage amplifier that generates the DC voltage necessary to bias the cascode devices. In this way, there is no need for external bias circuitry.
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