A radio frequency low noise amplifier circuit with a receive signal input, a receive signal output, and a voltage source include a low noise amplifier and a coupled inductor circuit with a primary inductive chain connected to the output of the low noise amplifier and to the voltage source. The coupled inductor circuit further includes a secondary inductive chain with a first inductor electromagnetically coupled to the primary inductive chain, and a second inductor in series with the first inductor and magnetically coupled to the primary inductive chain. The second inductor is connected to a feedback node of the low noise amplifier. There is an output matching network connected to the first inductor of the secondary inductive chain and to the receive signal output.

An amplifier includes a gain transistor including a control terminal to receive an input signal. A degeneration inductor is coupled between the first terminal of the gain transistor and ground. A shunt inductor and a capacitor are coupled in series between the control terminal of the gain transistor and ground, and form a filter to attenuate frequencies of the input signal within a frequency range. The degeneration inductor and the shunt inductor form a transformer to provide impedance matching.

Aspects of this disclosure relate to an impedance transformation circuit for use in an amplifier, such as a low noise amplifier. The impedance transformation circuit includes a matching circuit including a first inductor. The impedance transformation circuit also includes a second inductor. The first and second inductors are magnetically coupled to each other to provide negative feedback to linearize the amplifier.

An amplifier includes an input node, an output node, a transistor and a transformer. The input node is configured to receive a first signal. The output node is configured to output an amplified first signal. The transistor includes a first terminal, a second terminal and a third terminal. The first terminal is coupled to the input node and a first supply voltage source. The second terminal is coupled to a second supply voltage source and the output node. The third terminal is coupled to a reference node. The transformer is coupled to the first terminal and the third terminal. The transistor is configured to operate in a sub-threshold region and a near-triode region.

A radio frequency low noise amplifier circuit with a receive signal input, a receive signal output, and a voltage source include a low noise amplifier and a coupled inductor circuit with a primary inductive chain connected to the output of the low noise amplifier and to the voltage source. The coupled inductor circuit further includes a secondary inductive chain with a first inductor electromagnetically coupled to the primary inductive chain, and a second inductor in series with the first inductor and magnetically coupled to the primary inductive chain. The second inductor is connected to a feedback node of the low noise amplifier. There is an output matching network connected to the first inductor of the secondary inductive chain and to the receive signal output.

A transceiver circuit for transmitting and receiving via a single antenna interface, the transceiver circuit comprising: a transmitter arranged to send a transmit signal to the antenna interface; an amplifier arranged to receive a receive signal from the antenna interface; and a filter arranged between the antenna and the amplifier; wherein the transmitter circuit is arranged to source and/or sink current through an inductive element and wherein the inductive element is part of either the filter or the amplifier. This arrangement re-uses an inductive element that is already present within the circuit for other reasons (e.g., filtering, impedance matching, etc.). The inductive element may be any winding or coil. For example, it may be a stand-alone inductor, or it may be a transformer winding. Therefore, using an inductive element that is already present for other reasons saves area and in turn cost.

A transceiver circuit for transmitting and receiving via a single antenna interface, the transceiver circuit comprising: a transmitter and a receiver, wherein the receiver comprises: a first circuit branch arranged to selectively connect the receiver input to the receiver output; and a second circuit branch arranged to selectively connect the receiver input to a signal ground node. The receiver can be operated to choose which of the two circuit branches to send the signal. In receive mode, the receiver can send the signal over the first circuit branch to the receiver output as normal. In transmit mode, the receiver can send the signal instead over the second circuit branch to ground, thereby dumping the incoming signal, while protecting sensitive processing components downstream of the first circuit branch that are unable to handle the large signal swing of the direct path or reflected transmit pulse.

A push-pull amplifier includes a pair of active devices driving the primary side of a double distributed active transformer (DDAT). The primary side of the DDAT includes a cascaded arrangement of primary windings of a first set of transformers with the active devices coupled ends of cascaded arrangement of primary windings. The secondary side of the DDAT includes a cascaded arrangement of secondary windings of a second set of transformers coupled to a load. Secondary windings of the first set of transformers drive inputs of respective active stages. Outputs of the active stages drive respective primary windings of the second set of transformers.

An apparatus includes: first and second transistors, each of the first and second transistors includes a gate terminal, a source terminal, and a drain terminal; and a transformer including a primary winding and first and second secondary windings, the primary winding is coupled to a first input node configured to receive an input signal and a second input node configured to receive a potential, the first and second secondary windings are coupled to gate terminals of the first and second transistors and cross-coupled to source terminals of the first and second transistors.

Disclosed are apparatuses and methods to overcome technology limitations to achieve linearity and efficiency performance suitable for practical wireless communications systems. In an embodiment, an amplifier is provided that superimposes the transconductance from a common source amplifier with inductor degeneration with the transconductance from a common source amplifier without degeneration. In an embodiment, an amplifier is provided having a feedback-balun-transformer that provides electro-magnetic coupling between primary, secondary, and negative feedback degeneration inductors and a differential to single-ended conversion output.