ACTIVE CASCODE CIRCUIT USING BACKGATE CONTROL

摘要

An example embodiment of an active cascode circuit has a control circuit for control of the gate to source voltage (VGS) of at least one transistor in the active cascode circuit. The embodiment may be configured so that control of the VGS also controls the voltage Vin on the input. Vin may be adjusted without altering the device geometry or changing the drain current. This allows for better control and optimization of available headroom for the input voltage in low voltage designs and also results in higher active cascode circuit bandwidth and/or higher output impedance (Rout) for a given power level.

主权项

1. An active cascode circuit, comprising:
an input and an output; a first transistor coupled between the input and the output and having a gate; a load coupled between the gate and a first node; a second transistor having a backgate and a first, second and third terminal, the first terminal coupled to the gate, the second terminal coupled to the input, and the third terminal coupled to a second node; and, a control circuit having a control output coupled to the backgate of the second transistor, the control circuit configured to provide a voltage on the backgate of the second transistor to adjust the gate to source voltage (VGS) of the second transistor.