A power amplifier of the present invention comprises a first cascode including a MOSFET and a JFET and a first capacitor electrically connected between the source and the drain of the JFET. Two such power amplifiers in parallel form a differential power amplifier. In the differential amplifier a second capacitor can be electrically connected between the source and the drain of the second JFET. Another differential power amplifier comprises a first capacitor electrically connected between the gate of the first MOSFET and the source of the second MOSFET, and a second capacitor electrically connected between the gate of the second MOSFET and the source of the first MOSFET. Some of these differential power amplifiers also include capacitors electrically connected between the sources and the drains of the JFETs.

Some examples of the disclosure are directed to systems and methods for calibrating and operating transconductance amplifiers for high-bandwidth applications configured in open loop configurations. Some examples of the disclosure are directed to setting a gain of the transconductance amplifiers based upon a value of an output load. Some examples of the disclosure are directed to using auto-zeroing circuitry and gain correction circuitry to modify a biasing of a transconductance amplifier.

The present application discloses an amplifier and a method for controlling a common mode voltage thereof. The method includes: generating a control signal according to a positive-terminal input signal, a negative-terminal input signal and a target common mode voltage; and coupling the controlling signal to a first terminal of a positive-terminal capacitor and a first terminal of a negative-terminal capacitor, to adjust degree of conduction of a positive-terminal p-type transistor and degree of conduction of a negative-terminal p-type transistor, or to adjust degree of conduction of a positive-terminal n-type transistor and degree of conduction of a negative-terminal n-type transistor, thereby changing a common mode voltage.