Abstract: Circuits and methods for a radio frequency amplifier, such as an LNA, that include a wideband coupled input impedance matching network. One embodiment includes a first inductor coupled between a first terminal and a first node, the first terminal couplable to a degeneration terminal of an amplifier core; a second inductor coupled between a second terminal and either the first node or a second node, the second terminal couplable to an input terminal of the amplifier core; a third inductor coupled between the first node and a third terminal, the third terminal couplable to a reference potential; and, in a variant embodiment, a fourth inductor coupled between the second node and a fourth terminal, the fourth terminal couplable to the reference potential; wherein the first inductor and the second inductor are mutually coupled. Some embodiments allow multiple modes to allow tradeoffs of gain versus linearity and NF characteristics.

Abstract: Circuits and methods for an amplifier (particularly LNAs) that achieve wideband output impedance matching and high gain while simultaneously rejecting out-of-band (OOB) harmonic frequencies. Some embodiments allow multiple modes of operation to allow selection of gain versus linearity characteristics. One aspect of the present invention is improvement of the linearity and sensitivity of a whole RF “front end” (RFFE) receiver chain by suppressing OOB gain within an LNA component at higher order harmonic frequencies. Another aspect of the present invention are new wideband and ultra-wideband LNA load circuits that, while achieving high frequency OOB rejection, maintain in-band high gain and wideband output impedance matching at the same time. Yet another aspect of the present invention are new ultra-wideband LNA output impedance matching circuits.

Abstract: Methods and devices for reducing DC current consumption of a multi-stage LNA amplifier. According to one aspect, first and second amplification stages are stacked to provide a common conduction path of a DC current. The first stage includes a common-source amplifier, the second stage includes a common-drain amplifier. Coupling between the two stages is provided by series connection of load inductors of the respective stages and a capacitor coupled at a common node between the inductors. According to another aspect, a current splitter circuit is used to split a current to the first stage according to two separate conduction paths, one common path to the two stages, and another separate from the second stage. According to yet another aspect, the current splitter circuit includes a feedback loop that controls the splitting of the current so to maintain a constant current through the common path.

Abstract: Circuits and methods for a multi-gain mode amplifier, particularly an LNA, that achieves wideband output impedance matching and high gain while maintaining low power and a low NF in a highest gain mode, and which can switch to one or more lower gain modes that achieve higher linearity with lower power. In a highest gain mode, an inductor is selectively inserted between the amplified-signal terminal of an amplification core and an output LC output matching network. The inductor, when inserted, provides wideband output impedance matching, functioning as a series peaking inductor; accordingly, the inserted inductor delays current flow to the output capacitor and lowers the rise time of signal changes across the output capacitor. In addition, higher gain can be achieved compared to a conventional LC output impedance matching topology due to a higher impedance at the amplified-signal terminal of the amplification core.