Electronic devices, local oscillator circuits, and methods for operating local oscillators are disclosed herein. In one embodiment, a local oscillator circuit includes a first transistor and a second transistor individually having a base, a collector, and an emitter and a transformer having a first transformer inductor magnetically coupled to a second transformer inductor. The first transformer inductor couples the collector of the first transistor to the base of the second transistor. The second transformer inductor couples the collector of the second transistor to the base of the first transistor.

The present invention discloses a gain-boosted n-path passive-mixer-first receiver. According to another aspect of the present disclosure, a gain-boosted n-path passive-mixer-first receiver is provided. The receiver includes a number n of switch-capacitor (sc) sets, a resistor, and a transconductance amplifier. The sc sets connect in parallel, and the sc sets have a first node and a second node. The resistor connects to the first node. The transconductance amplifier connects to the resistor and the second node.

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.

According to another aspect of the present disclosure, a radio-frequency-to-baseband-function-reuse receiver with shared amplifiers for common-mode and differential-mode amplification is provided. The receiver includes two set networks connected in parallel. The set networks includes a first and a second input capacitors, a first and a second output capacitors, a first transconductance amplifier having an input terminal, a second transconductance amplifier having an input terminal, a first switch, and a second switch. The first and the second input capacitors connect to a first node. The first and the second output capacitors connect to a second node. The first transconductance amplifier connects between the first input capacitor and the first output capacitor. The second transconductance amplifier connects between the second input capacitor and the second output capacitor. The first switch connects between the input terminal of the first transconductance amplifier and the second node. The second switch connects between the input terminal of the second transconductance amplifier and the second node.

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.

Methods and systems for a distributed transmission line multiplexer for a multi-core multi-mode voltage-controlled oscillator (VCO) may comprise a plurality of voltage controlled oscillators (VCOs) arranged adjacent to each other, where each of the plurality of VCOs are operable to generate an output signal at a configurable frequency, an impedance matching circuit comprising a respective driver and impedance matching elements coupled to each of the plurality of VCOs, and an output device coupled to the impedance matching circuit. The impedance matching elements may include capacitors and inductors. Between each adjacent pair of the respective drivers coupled to each of the plurality of VCOs, the impedance matching elements may include two inductors coupled in series between the drivers and a capacitor coupled to ground and to a common node between the two inductors. Impedance values of the capacitors and inductors may be configurable. The impedance matching elements may include a resistor coupled to a bias voltage VDD and to a common node with a capacitor that is coupled to ground, where the common node is coupled to one of the inductors. The output device may include a prescaler that is an integer or fractional frequency-N divider, or a buffer. The respective drivers coupled to each of the plurality of VCOs may be configured to provide a constant output power no matter which of said plurality of VCOs is enabled.

A circuit includes a first oscillator and a second oscillator. The first oscillator includes an inductive device, a capacitive device, and an active feedback device configured to output a first output signal having a predetermined frequency according to electrical characteristics of the inductive device of the first oscillator and electrical characteristics of the capacitive device of the first oscillator. The second oscillator includes an inductive device, a capacitive device, and an active feedback device configured to output a second output signal having the predetermined frequency according to electrical characteristics of the inductive device of the second oscillator and electrical characteristics of the capacitive device of the second oscillator. The inductive device of the first oscillator and the inductive device of the second oscillator are magnetically coupled.

A phase-locked loop comprises a voltage controlled oscillator. The voltage controlled oscillator comprises an inductor and a capacitor, connected in parallel, and also connected in parallel therewith, a negative resistance structure. A first terminal of the negative resistance structure is connected to respective first terminals of the inductor and the capacitor. A second terminal of the negative resistance structure is connected to respective second terminals of the inductor and the capacitor. The negative resistance structure exhibits a tunable capacitance, such that a frequency of an output of the voltage controlled oscillator can be tuned by a control input signal, and the control input signal is generated in the phase-locked loop. The negative resistance structure comprises first and second transistors.