A low noise amplifier includes at least two variable gain amplifier stages, each variable gain amplifier configured to accept an input signal and to provide a load driving signal; a tunable bandpass filter connected as a load to each variable gain amplifier stage, wherein each bandpass filter includes a resonant tank, each resonant tank including an inductor, wherein each inductor of each resonant tank is oriented in orthogonal relation with respect to each respective longitudinal axis of each next inductor, the orthogonal relation of the respective longitudinal axes configured to reduce mutual coupling between the tunable bandpass filters; a cross-coupled transistor pair, and at least one cross-coupled compensation transistor pair biased in a subthreshold region configured to add a transconductance component as a function of a load driving signal; and, a controller circuit configured to tune each tunable bandpass filter.

A low noise amplifier includes at least two variable gain amplifier stages, each variable gain amplifier configured to accept an input signal and to provide a load driving signal; a tunable bandpass filter connected as a load to each variable gain amplifier stage, wherein each bandpass filter includes a resonant tank, each resonant tank including an inductor, wherein each inductor of each resonant tank is oriented in orthogonal relation with respect to each respective longitudinal axis of each next inductor, the orthogonal relation of the respective longitudinal axes configured to reduce mutual coupling between the tunable bandpass filters; a cross-coupled transistor pair, and at least one cross-coupled compensation transistor pair biased in a subthreshold region configured to add a transconductance component as a function of a load driving signal; and, a controller circuit configured to tune each tunable bandpass filter.

A low noise amplifier includes at least two variable gain amplifier stages, each variable gain amplifier configured to accept an input signal and to provide a load driving signal; a tunable bandpass filter connected as a load to each variable gain amplifier stage, wherein each bandpass filter includes a resonant tank, each resonant tank including an inductor, wherein each inductor of each resonant tank is oriented in orthogonal relation with respect to each respective longitudinal axis of each next inductor, the orthogonal relation of the respective longitudinal axes configured to reduce mutual coupling between the tunable bandpass filters; a cross-coupled transistor pair, and at least one cross-coupled compensation transistor pair biased in a subthreshold region configured to add a transconductance component as a function of a load driving signal; and, a controller circuit configured to tune each tunable bandpass filter.

A low noise amplifier includes at least two variable gain amplifier stages, each variable gain amplifier configured to accept an input signal and to provide a load driving signal; a tunable bandpass filter connected as a load to each variable gain amplifier stage, wherein each bandpass filter includes a resonant tank, each resonant tank including an inductor, wherein each inductor of each resonant tank is oriented in orthogonal relation with respect to each respective longitudinal axis of each next inductor, the orthogonal relation of the respective longitudinal axes configured to reduce mutual coupling between the tunable bandpass filters; a cross-coupled transistor pair, and at least one cross-coupled compensation transistor pair biased in a subthreshold region configured to add a transconductance component as a function of a load driving signal; and, a controller circuit configured to tune each tunable bandpass filter.

A receiver front-end capable of receiving RF inputs having a broad range of levels. The receiver comprises a low-noise amplifier (LNA) operating in a variety of bias modes that cover a large gain range. Branches of the amplifier can be turned on in various combinations to allow selection of different bias modes. A degeneration inductor coupled to the source of the common source FET of each branch has a plurality of taps that are coupled to degeneration switches that can ground the tap to effectively shorten the degeneration inductor and reduce the amount of degeneration inductance. The degeneration inductor and associated switches can be fabricated using one of several physical layouts. Operating the degeneration switches to select the length of the degeneration inductor to match the bias mode reduces changes in the input impedance as different bias modes are selected.

Certain aspects of the present disclosure generally relate to voltage-controlled oscillators (VCOs) using a lowered or an adjustable negative transconductance (g.sub.m) compared to conventional VCOs. This g.sub.m degeneration technique suppresses the noise injected into an inductor-capacitor (LC) tank of the VCO, thereby providing lower signal-to-noise ratio (SNR) for a given VCO voltage swing, lower power consumption, and decreased phase noise. One example VCO generally includes a resonant tank circuit, an active negative transconductance circuit connected with the resonant tank circuit, and a bias current circuit for sourcing or sinking a bias current through the resonant tank circuit and the active negative transconductance circuit to generate an oscillating signal. The active negative transconductance circuit includes cross-coupled transistors and an impedance connected between the cross-coupled transistors and a reference voltage.

Certain aspects of the present disclosure generally relate to voltage-controlled oscillators (VCOs) using a lowered or an adjustable negative transconductance (g.sub.m) compared to conventional VCOs. This g.sub.m degeneration technique suppresses the noise injected into an inductor-capacitor (LC) tank of the VCO, thereby providing lower signal-to-noise ratio (SNR) for a given VCO voltage swing, lower power consumption, and decreased phase noise. One example VCO generally includes a resonant tank circuit, an active negative transconductance circuit connected with the resonant tank circuit, and a bias current circuit for sourcing or sinking a bias current through the resonant tank circuit and the active negative transconductance circuit to generate an oscillating signal. The active negative transconductance circuit includes cross-coupled transistors and an impedance connected between the cross-coupled transistors and a reference voltage.

Certain aspects of the present disclosure generally relate to voltage-controlled oscillators (VCOs) using a lowered or an adjustable negative transconductance (g.sub.m) compared to conventional VCOs. This g.sub.m degeneration technique suppresses the noise injected into an inductor-capacitor (LC) tank of the VCO, thereby providing lower signal-to-noise ratio (SNR) for a given VCO voltage swing, lower power consumption, and decreased phase noise. One example VCO generally includes a resonant tank circuit, an active negative transconductance circuit connected with the resonant tank circuit, and a bias current circuit for sourcing or sinking a bias current through the resonant tank circuit and the active negative transconductance circuit to generate an oscillating signal. The active negative transconductance circuit includes cross-coupled transistors and an impedance connected between the cross-coupled transistors and a reference voltage.

A nonlinear design is described to reliably detect very weak signals buried in noisy environments and subject to environmental noises. This design does not require knowledge of prior data and is capable of detecting the amplitude and phase of the weak signal based on the data from a single sensor.