A low-noise amplifier (LNA) includes a first transistor, a second transistor, and a load coupled to a drain of the first transistor and a drain of the second transistor. The LNA also includes a first reactive impedance matching network including a first inductor and a second inductor inductively coupled with the first inductor, wherein the first inductor is coupled to a source of the first transistor, and the second inductor is coupled to a gate of the first transistor. The LNA also includes a second reactive impedance matching network including a third inductor and a fourth inductor inductively coupled with the third inductor, wherein the third inductor is coupled to a source of the second transistor, and the fourth inductor is coupled to a gate of the second transistor. The LNA also includes a switching circuit configured to enable or disable each of the reactive impedance matching networks.

In some aspects, a programmable amplifier may comprise an n-channel metal-oxide-semiconductor (NMOS) amplification path and a complementary metal-oxide-semiconductor (CMOS) amplification path. In some aspects, the NMOS amplification path may include a first NMOS transistor and a second NMOS transistor that are connected in parallel between an input and an output. In some aspects, the CMOS amplification path may include a p-channel metal-oxide-semiconductor (PMOS) transistor connected in parallel with the first NMOS transistor between the input and the output. In some aspects, the programmable amplifier may further comprise a plurality of switches that are programmable to switch the PMOS transistor off in a first mode, such as an NMOS mode or a high linearity mode, and to switch the second NMOS transistor off in a second mode, such as a CMOS mode or a low current mode. Numerous other aspects are described.

A system and method which includes receiving an input signal having an envelope and generating an envelope detection signal corresponding to the envelope. A bias current provided to an amplifier circuit is adjusted based upon the envelope detection signal, the amplifier circuit including an amplifier and a transformer. The transformer is configured to establish a magnetically coupled feedback loop from an output of the amplifier to an input of the amplifier. An output signal is provided, by the amplifier circuit, in response to the input signal.

Examples of the disclosure include a balun comprising a primary winding disposed in a first plane, the primary winding being characterized by a longitudinal axis and a first outer radial distance extending from the longitudinal axis to an outermost edge of the primary winding, and a secondary winding disposed in a second plane, the secondary winding being characterized by the longitudinal axis and a second outer radial distance extending from the longitudinal axis to an outermost edge of the secondary winding, the first outer radial distance being equal to or greater than the second outer radial distance.

Aspects of the present disclosure provide a circuit configured to adjust an input impedance of an amplifier such as a low-noise amplifier. In certain aspects, the circuit is coupled to a node, wherein the node is between a first transistor and a second transistor of the amplifier. The circuit may include an inductor and a capacitor coupled in series, wherein the inductor is coupled with one or more load inductors of the amplifier through negative magnetic coupling.

A LNA comprises an input, a transformer structure and a first transistor and a second transistor, each having with gate, source, and drain terminals. The transformer structure has a first winding pair, a second winding pair and a third winding pair. Each winding of the first winding pair connects to the input node and one source terminals of the transistors. The second winding pair is proximate the first winding pair. The second winding pair connects to a ground node and the transistor source terminals. The third winding pair is proximate the first winding pair and it connects to a bias signal source and a gate terminal of the transistors. An output connects to the transistor drain terminals. The winds of the first and second winding pairs are off set and rotated 180 degrees with respect to the other winding in the pair. The third winding performs a Gm boost function.

A circuit comprising: an input terminal; a first amplifier coupled to the input terminal of the circuit to receive an input signal; a first inductor having a first terminal coupled to the input terminal and a second terminal configured to be coupled to the ground terminal, wherein the first inductor is arranged with a second inductor and configured to magnetically couple therewith, wherein said second inductor is coupled to the first amplifier and is configured to sense a current through the amplifier.