Apparatus and methods for LNAs with mid-node impedance networks are provided herein. In certain configurations, an LNA includes an input, an output, a transconductance device, a cascode device, and a mid-node impedance network. The transconductance device generates an amplified signal by amplifying an input signal received at the input, and provides the amplified signal to the output via the cascode device. The mid-node impedance network is electrically connected between the transconductance device and the cascode device, and provides compensation for a parasitic capacitance of the gm device, thereby enhancing the LNA's performance.

A multi-stage low-noise amplifier (LNA) device with a band pass response includes a first LNA in series with a second LNA. The device further includes multiple outputs coupled to the second LNA. Each of the outputs is capable of being active at the same time. The device further includes a high pass filter coupled between the first LNA and the second LNA.

A reset signal is generated by a TIA circuit alone. In an embodiment, a transimpedance amplifier configured to convert a current signal into a voltage signal includes a transimpedance stage including an amplification stage constituted of a transistor with a grounded emitter, and a comparator configured to compare a collector voltage of the transistor with a reference voltage and output a reset signal.

A self-biasing output booster amplifier having an input amplifier stage, an output amplifier stage being operatively connected to an output of the input amplifier stage, and first and second current copying circuits. The second current copying circuit is biased from an output of the self-biasing output booster amplifier. The first and second current copying circuits are configured to copy at least a portion of the current through the output amplifier stage. The sum of the output of the second current copying circuit and the output of the output amplifier stage provides the output current of the self-biasing output booster amplifier, Finally, the input amplifier stage is biased from the output of the second current copying.

An amplifier circuits inductive/magnetic sensor interface can include a main signal path including one or more amplifiers configured to receive an input signal and to produce an output signal based on the input signal. The input signal may include a square-wave demodulated signal having an associated modulation frequency and an undesired frequency component at twice the modulation frequency of the square-wave demodulated signal. The amplifier circuit may include a gain feedback loop configured to set a gain of the amplifier circuit. The amplifier circuit may include a ripple reduction feedback loop configured to receive an intermediate signal on the main signal path and extract the undesired frequency component of the intermediate signal to produce a filtered version of the intermediate signal and provide the filtered version of the intermediate signal to the main signal path.

Techniques for providing low-cost and effective jammer rejection for an amplifier is disclosed. The amplifier includes an input node and an output node, a first transistor and a second transistor, a load circuitry, an inductor, and a capacitor. A first terminal of the first transistor is coupled to a ground. A second terminal of the first transistor is coupled to a first terminal of the second transistor. A second terminal of the second transistor is coupled to the output node. The load circuitry is coupled between a power supply and the second terminal of the second transistor. A first terminal of the inductor is coupled to the ground through a first switch. A first terminal of the capacitor is coupled to the first terminal of the second transistor and a second terminal of the capacitor is coupled to a second terminal of the inductor.

Radio frequency (RF) front-end circuitry that includes control circuitry and an RF filter structure that includes a plurality of resonators are disclosed. In one embodiment, a first tunable RF filter path is defined by a first set of the plurality of resonators such that the first tunable RF filter path has a first amplitude and a first phase. A second tunable RF filter path is defined by a second set of the plurality of resonators such that the second tunable RF filter path has a second amplitude and a second phase. To provide antenna diversity and/or beam forming/beam steering, the control circuitry is configured to set a first amplitude difference between the first amplitude and the second amplitude to approximately a first target amplitude difference and set a first phase difference between the first phase and the second phase to approximately a first target phase difference.

A self-biasing output booster amplifier having an input amplifier stage, an output amplifier stage being operatively connected to an output of the input amplifier stage, and first and second current copying circuits. The second current copying circuit is biased from an output of the self-biasing output booster amplifier. The first and second current copying circuits are configured to copy at least a portion of the current through the output amplifier stage. The sum of the output of the second current copying circuit and the output of the output amplifier stage provides the output current of the self-biasing output booster amplifier, Finally, the input amplifier stage is biased from the output of the second current copying.

A reset signal is generated by a TIA circuit alone. In an embodiment, a transimpedance amplifier configured to convert a current signal into a voltage signal includes a transimpedance stage including an amplification stage constituted of a transistor with a grounded emitter, and a comparator configured to compare a collector voltage of the transistor with a reference voltage and output a reset signal.

A power amplifier is described. A power amplifier includes at least a first amplifier stage. The power amplifier also includes a first notch filter coupled with the first amplifier stage. The first notch filter is configured to tune to a first frequency. The first notch filter including at least one first set of metal oxide semiconductor variable capacitor arrays. Moreover, the power amplifier includes a first mirrored notch filter coupled with said first amplifier stage. The first mirror notch filter is configured to tune to the mirror of the first frequency. The first mirror notch filter including at least one second set of metal oxide semiconductor variable capacitor arrays.