Systems and methods are disclosed for improved linearity performance of a mixer. An example mixer includes switching circuit elements configured to be switched on and switched off based at least partly on a local oscillator signal and capacitors including a respective capacitor in parallel with each of the switching elements. The mixer is configured to mix the input signal with the local oscillator signal to thereby frequency shift the input signal.

An integrated circuit that selectively filters out common-mode and differential signals is described. This integrated circuit may include an RF receiver with a mixer that converts signals between a band of frequencies in the RF and a second band of frequencies based at least in part on second signals, where the second band of frequencies is less than the band of frequencies. Moreover, the mixer may include input ports that receive the second signals and include a filter circuit, electrically coupled in parallel with the input ports, that filters out the common-mode signals above a threshold frequency and filters out the differential signals below the threshold frequency. For example, the filter circuit may include a half-wavelength transmission line. Note that the mixer may convert the differential signals to the common-mode signals below the threshold frequency and may convert the common-mode signals to the differential signals above the threshold frequency.

A down-conversion mixer includes a transconductance unit, a resonant unit and a mixing unit. The transconductance unit converts a differential input voltage signal pair into a differential input current signal pair. The resonant unit provides a negative resistance and a differential auxiliary current signal pair. The mixing unit mixes a combination of the differential input current signal pair and the differential auxiliary current signal pair with a differential oscillatory voltage signal pair to generate a differential mixed voltage signal pair.

A reflective modulator comprises a coupler, two diodes and two DC block units. The coupler has an input end used to output an output signal, an output end used to output an output signal, a first load end connected to one of the diodes and a second load end connected to another one of the diodes. The DC block units connect between the diodes and the coupler for DC blocking. A message signal is selectively inputted to both of the two DC block units for operating the state of the two diodes. A BPSK modulator using the reflective modulator and a quadrature modulator using the BPSK modulator are also introduced.

Transmit and/or receive beamforming signal generation includes a voltage-controlled oscillator (VCO) for generating a lower or higher master frequency output signal in accordance with a selection of a lower or higher frequency carrier frequency. A local oscillator generates local oscillator signals in quadrature in response to the maser frequency output signal. One or more mixer stages generate sidebands in response to a received information signal and the local oscillator signals in quadrature. The one or more mixer stages generate an output information signal in response to high-side injection of lower sidebands of the developed sidebands when the lower frequency carrier frequency is selected, and generate the output information signal in response to low-side injection of higher sidebands of the developed sidebands when the higher frequency carrier frequency is selected. Multi-band operation of transmit and receive arrays can be performed.

A mixer includes a transconductance circuit and a mixing circuit. The transconductance circuit includes a capacitor and first and second transconductance modules. The first transconductance module converts a single-ended to-be-shifted voltage signal at a first terminal of the capacitor into a first input current signal. The second transconductance module converts a voltage signal at a second terminal of the capacitor into a second input current signal that cooperates with the first input current signal to constitute a differential input current signal pair. The mixing circuit mixes the differential input current signal pair with a differential oscillatory voltage signal pair to generate a differential mixed voltage signal pair.

A configurable passive mixer is described herein. According to one exemplary embodiment, a passive mixer for a wireless receiver comprises a plurality of passive mixer cores coupled in parallel with each mixer core configured to receive a same set of radio frequency input signals and a separately driven set of local oscillator input signals. Further, each mixer core is configured to be separately enabled or disabled so that the passive mixer can be selectively configured during operation to convert the same set of radio frequency input signals to a set of downconverted output signals that satisfy a certain performance requirement or performance parameter of the passive mixer.

A mixer includes a trans conductance unit, a gain boost unit, a mixing module and a buffer. The trans conductance unit, the gain boost unit and the mixing module cooperatively mix a differential input voltage signal pair with a differential oscillatory voltage signal pair to generate a differential mixed voltage signal pair. The buffer performs buffering on the differential mixed voltage signal pair, and has inductance that cooperates with parasitic capacitance at output terminals thereof to form an LC tank circuit that reaches resonance at a frequency of the differential mixed voltage signal pair to behave as an open circuit.

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 double-balanced FET mixer may include: single-ended RF port that receives or delivers single-ended RF signal; RF balun that converts the received single-ended RF signal into differential RF signal or generates delivered single-ended RF signal from received differential RF signal; local oscillator input port receives local oscillator signal; direct IF port receives or delivers an IF signal; and at least two FETs process the local oscillator signal and generate or process the differential RF signal and IF signal. The mixer may have no IF balun separate and distinct from tRF balun; may receive an input signal at RF port and generates output signal at IF port. The mixer may receive input signal at IF port and generate an output signal at the RF port, the output signal in either case being plus or minus the local oscillator signal. The double-balanced FET mixer may operate with IF frequencies down to DC.