The present disclosure generally relates to the field of receiver structures in radio communication systems and more specifically to passive mixers in the receiver structure and to a technique for converting a first signal having a first frequency into a second signal having a second frequency by using a third signal having a third frequency. A passive mixer for converting a first signal having a first frequency into a second signal having a second frequency by using a third signal having a third frequency comprises a cancellation component 220 for generating a first cancellation signal for cancelling second order intermodulation components by superimposing the first signal weighted by a cancellation value on the third signal; and a mixing component 231 having a first terminal 232 for receiving the first signal, a second terminal 234 for outputting the second signal, and a third terminal 236 for receiving the first cancellation signal, wherein the mixing component 231 is adapted to provide the second signal as output at the second terminal 234 by mixing the first signal provided as input at the first terminal 232 and the first cancellation signal provided as input at the third terminal 236.

A frequency multiplier includes an input section having inputs to receive an input signal having an input frequency, a mixer section, and an output section magnetically coupled to the input section and generating an output signal in response to the input signal. The mixer section may be coupled to the input section by a common mode node forming a path for a common mode current to flow to the mixer section and be magnetically coupled to the common mode node. The input section may generate a signal current, and the mixer section may be magnetically coupled to the input section and be directly capacitively coupled to the input section through a capacitor in a signal current path. The mixer section may have differential inputs capacitively coupled to the input section and also be coupled to the input section through a current path. A current helper section may be coupled to the current path.

Noise parameters are used to characterize noise performance of linear devices, such as amplifiers. Such noise parameters have not been used for frequency conversion devices, such as mixers. Direct measurements of single-side-band noise figures are accurately represented by the measured noise parameters, which fully characterize the noise figure of the mixers for all harmonic impedance loading conditions. Each harmonic side band of frequencies contributing noise to the mixer output is associated with a set of noise parameters. A measurement method for extracting the noise parameters is described.

A combined mixer and filter circuitry is disclosed. The combined mixer and filter circuitry comprises a mixer comprising a first input, a second input and an output. The combined mixer and filter circuitry further comprises a filter comprising an active inductor and a first capacitor. The active inductor comprises a transistor having a first terminal, a second terminal and a third terminal and a resistor connected between the first terminal of the transistor and a voltage potential. The first capacitor is connected between the third terminal and a signal ground and the second terminal of the transistor is connected to the second input of the mixer.

Mixers with improved linearity are disclosed. A diode or FET ring mixer is implemented with at least one parallel shunt element coupled with the ring mixer, the shunt element providing shunt to a diode or FET, for example, to reduce the effect of nonlinear or off resistance and/or capacitance. Linearity, isolation, symmetry, even order harmonics of the ring mixer, or any combination thereof can be improved as a result. The linearity of the ring mixer with parallel shunt resistors can be further improved by adding series resistors in the ring according to certain embodiments.

A switch circuit, a mixer, and an electronic device, where the switch circuit includes a first metal oxide semiconductor (MOS) transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor, both a gate of the first MOS transistor and a gate of the fourth MOS transistor are connected to a first port, and both a gate of the second MOS transistor and a gate of the third MOS transistor are connected to a second port; and a lead between the gate of the first MOS transistor and the first port, a lead between the gate of the second MOS transistor and the second port, a lead between the gate of the third MOS transistor and the second port, and a lead between the gate of the fourth MOS transistor and the first port all have an equal length. In this way, linearity is relatively high.

A FET based double balanced mixer (DBM) that exhibits good conversion gain and IIP3 values and provides improved linearity and wide bandwidth. In one embodiment, a first balun is configured to receive a local oscillator (LO) signal and generate two balanced LO signals that are coupled to two corresponding opposing nodes of a four-node FET ring. A second balun is configured to pass an RF signal on the unbalanced side. The FET ring includes at least four FETs connected as branches of a ring, with the source of each FET connected to the drain of a next FET in the ring. Each FET is preferably fabricated as, or configured as, a low threshold voltage device having its gate connected to its drain, which causes the FET to operate as a diode, but with the unique characteristic of having close to a zero turn-on voltage.

A signal mixing circuit device includes a first mixer, a second mixer and a signal amplifying circuit serially connected to the first mixer; the first mixer includes an RF signal input terminal for receiving an RF signal, LO signal input terminals for sampling a first and second LO signals, a first mixed-signal output terminal for outputting a first mixed signal and a second mixed-signal output terminal for outputting a second mixed signal; the second mixer includes an input terminal connected to a capacitor, two mixed-signal output terminals respectively connected to the first and second mixed-signal output terminals of the first mixer, LO signal input terminals for inversely sampling the first and second LO signals. With the double-balance nature of the second mixer core, the noise at the LO signal input terminals of the first mixer can be cancelled. A receiver includes the signal mixing circuit device is also disclosed.

A configurable passive mixer is described herein. According to one exemplary embodiment, the passive mixer comprises a clock generator, a controller, and a plurality of passive mixer cores connected in parallel. The clock generator comprises a local oscillator drive unit for each passive mixer core. The controller varies an effective transistor size of the passive mixer by separately configuring each of the passive mixer cores to enable/disable each passive mixer core. For example, the controller may selectively enable one or more of the passive mixer cores to vary the effective transistor width of the passive mixer. As the performance requirements and/or the operating communication standard change, the controller may re-configure each passive mixer core.

A user equipment (UE), receiver and method are generally described herein. The UE may include a mixer, a local oscillator (LO) and an analog-to-digital converter (ADC). The mixer may downconvert a differential radio frequency (RF) signal using LO signals and provide downconverted signals to the ADC. The mixer may provide decoupled lowpass filtering. The lowpass filter capacitors may retain charge when discharging is completed. For each differential signal, the mixer may have an input pullup resistor, first switches receiving the signal and driven by different LO signals, second switches receiving signals from the first switches such that connected pairs of switches may have driven by different LO signals, an ADC input resistor, charging capacitors each connected between first switches driven by the same LO signal, and grounding capacitors each connected to second switches associated with different RF signal outputs and driven by different LO signals.