A current feedback amplifier (CFA). The CFA includes a common-gate input stage, a biasing circuitry, and a differential pair coupled in parallel between the supply voltage node and the reference voltage node. The common-gate input stage amplifies an input signal received at an input node and supplies it to a gate of the complementary transistors of the differential pair. The biasing circuitry supplies a bias voltage to a gate of the transistors of the common-gate input stage. The input node of the common-gate input stage and a node between the complementary transistors in the first path of the differential pair are shorted.

A balanced differential transimpedance amplifier with a single-ended input operational over a wide variation in the dynamic range of input signals. A threshold circuit is employed to either or a combination of (1) generate a varying decision threshold to ensure a proper slicing over a wide range of input current signal levels; and (2) generate a bias current and voltage applied to an input of a transimpedance stage to cancel out a dependence of the transimpedance stage voltage input on input current signal levels.

A system may include a front end differential amplifier having two input terminals, two input resistors, each of the two input resistors coupled to a respective one of the two input terminals, and an input common mode biasing circuit for an output stage of the front end differential amplifier, the input common mode biasing circuit comprising two current sources configured to generate currents for biasing the output stage of the front end differential amplifier.

A system may include a front end differential amplifier having two input terminals, two input resistors, each of the two input resistors coupled to a respective one of the two input terminals, and an input common mode biasing circuit for an output stage of the front end differential amplifier, the input common mode biasing circuit comprising two current sources configured to generate currents for biasing the output stage of the front end differential amplifier.

Bidirectional variable gain amplifiers (VGAs) for radio frequency (RF) communication systems are provided. In certain embodiments, a bidirectional VGA includes a first amplifier having an input coupled to a transmit/receive port, a second amplifier having an output coupled to a transmit port, a third amplifier having an input coupled to a receive port, a fourth amplifier having an output coupled to the transmit/receive port and to the input of the first amplifier, and a switch circuit that connects an output of the first amplifier to an input of the second amplifier in a transmit mode, and that connects an output of the third amplifier to an input of the fourth amplifier in a receive mode.

An amplifier that amplifies a differential signal includes first and second input terminals for receiving two input signals; first and second diodes each including an anode and a cathode, the anodes being electrically connected to the first and second input terminals; first and second bias current sources being respectively electrically connected to the cathodes of the first and second diodes; an operational amplifier connected to the cathode of the first diode and the cathode of the second diode and configured to amplify a differential signal between signals generated at the cathodes of the first and second diodes; a capacitive element being electrically connected between an input and an output of the operational amplifier; and a differential amplifier provided between the operational amplifier and the first and second input terminals and configured to amplify the two input signals. The first and second bias current sources include a current mirror circuit.

An amplifier that amplifies a differential signal includes first and second input terminals for receiving two input signals; first and second diodes each including anode and cathode, the anodes being electrically connected to the first and second input terminals; first and second bias current sources being respectively electrically connected to the cathodes of the first and second diodes; an operational amplifier connected to the cathode of the first diode and the cathode of the second diode and configured to amplify a differential signal between signals generated at the cathodes of the first and second diodes; a capacitive element being electrically connected between an input and an output of the operational amplifier; and a differential amplifier provided between the operational amplifier and the first and second input terminals and configured to amplify the two input signals. The first and second bias current sources include a current mirror circuit.

A current feedback amplifier (CFA). The CFA includes a common-gate input stage, a biasing circuitry, and a differential pair coupled in parallel between the supply voltage node and the reference voltage node. The common-gate input stage amplifies an input signal received at an input node and supplies it to a gate of the complementary transistors of the differential pair. The biasing circuitry supplies a bias voltage to a gate of the transistors of the common-gate input stage. The input node of the common-gate input stage and a node between the complementary transistors in the first path of the differential pair are shorted.