Adjustable gain for multi-stacked amplifiers

摘要

Techniques for providing adjustable gain in an amplifier. In an aspect, a composite amplifier having adjustable gain includes a plurality of amplifiers coupled in parallel, wherein each of the amplifiers may be turned on or off to adjust the overall gain of the composite amplifier. Each amplifier may include an input transistor and at least two cascode transistors. To turn each amplifier off, the gate voltage of a second or lowermost cascode transistor coupled to the input transistor may be grounded, and the gate voltage of a first cascode transistor coupled to the output voltage may be coupled to a first turn-off voltage to reduce the drain-to-gate voltage drop across the first cascode transistor. Further aspects provide for decoupling a capacitor coupled to the gates of the cascode transistors from AC ground when the amplifier is turned off.

主权项

1. An apparatus comprising:
at least two amplifiers coupled in parallel, each amplifier comprising:
a first cascode transistor coupled to a first configurable gate bias voltage;a second cascode transistor coupled to a second configurable gate bias voltage; andan input transistor coupled to an input voltage; wherein the first configurable gate voltage is set to a first turn-off voltage when such amplifier is turned off and when at least one other of the at least two amplifiers is turned on, the first turn-off voltage selected to reduce a drain-to-gate voltage of the first cascode transistor relative to setting the gate voltage of the first cascode transistor to ground; wherein, when one of the at least two amplifiers is turned off, the second configurable gate voltage is set to ground.