Tunable filters, cancellers, and duplexers based on passive mixers. A tunable delay cell includes passive mixers electrically coupled together for receiving an input signal and outputting a delayed signal, each passive mixer comprising a plurality of mixer switches. The tunable delay includes a control circuit for providing, to each passive mixer, a respective plurality of local oscillator (LO) signals, one to each mixer switch of each passive mixer. The control circuit is configured to vary the LO signals to cause a target frequency band of the input signal to be delayed by a target delay time in propagating through the passive mixers.

A passive mixer may include an output coupled to a next stage circuit. The output may be coupled to baseband inputs via first switches. The passive mixer may further include a tunable capacitor bank. The tunable capacitor bank may be coupled via second switches to the baseband inputs.

Superconducting device applications implemented with a surface acoustic wave resonator and a superconducting microwave resonator coupled to a Josephson ring modulator are provided. A method can comprise receiving, by a microwave Josephson mixer, and from a superconducting surface acoustic wave resonator of a superconducting device, a surface acoustic wave signal that comprises one or more phonons that resonate at a first frequency. The method can also comprise receiving, by the microwave Josephson mixer and from a superconducting microwave resonator of the superconducting device, a microwave signal that comprises one or more photons that can resonate at a second frequency. Further, the method can also comprise mixing, by the microwave Josephson mixer, the surface acoustic wave signal and the microwave signal based on a microwave control signal received from a microwave source operatively coupled to the microwave Josephson mixer.

A passive mixer may include an output coupled to a next stage circuit. The output may be coupled to baseband inputs via first switches. The passive mixer may further include a tunable capacitor bank. The tunable capacitor bank may be coupled via second switches to the baseband inputs.

A receiver includes circuitry configured to determine one or more first local oscillator (LO) harmonics that correspond to one or more first spectrum segments of a down-converted received signal based on characteristics of the received signal. The one or more first LO harmonics of the received signal are amplified by applying one or more first transconductance coefficients to one or more first harmonic selective transinductance amplifiers (TIAs) corresponding to the one or more first spectrum segments. Digitized outputs of the plurality of harmonic selective TIAs are calibrated based on an amount of signal leakage between the plurality of spectrum segments of the down-converted received signal.

A circuit for spatial equalization, comprising: circuit elements each comprising four variable transconductors, in each of the circuit elements: an input of a first variable transconductor (VT) is connected to an input I and an output of the first VT is connected to an output I; an input of the second VT is connected to an input Q and an output of the second VT is connected to output I; an input of the third VT is connected to input I and an output of the third VT is connected to the output Q; and an input of the fourth VT is connected to input Q and an output of the fourth VT is connected to output Q; the input I of each of the first plurality of circuit elements are connected together; and the input Q of each of the first plurality of circuit elements are connected together.

A receiver includes circuitry configured to determine one or more first local oscillator (LO) harmonics that correspond to one or more first spectrum segments of a down-converted received signal based on characteristics of the received signal. The one or more first LO harmonics of the received signal are amplified by applying one or more first transconductance coefficients to one or more first harmonic selective transinductance amplifiers (TIAs) corresponding to the one or more first spectrum segments. Digitized outputs of the plurality of harmonic selective TIAs are calibrated based on an amount of signal leakage between the plurality of spectrum segments of the down-converted received signal.

Tunable filters, cancellers, and duplexers based on passive mixers. A tunable delay cell includes passive mixers electrically coupled together for receiving an input signal and outputting a delayed signal, each passive mixer comprising a plurality of mixer switches. The tunable delay includes a control circuit for providing, to each passive mixer, a respective plurality of local oscillator (LO) signals, one to each mixer switch of each passive mixer. The control circuit is configured to vary the LO signals to cause a target frequency band of the input signal to be delayed by a target delay time in propagating through the passive mixers.

Embodiments are provided for biasing circuits with compensation of process variation without band-gap referenced current or voltage. In an embodiment, a circuit for biasing a field-effect transistor (FET) passive mixer comprises a series of diode-connected FETs, and a series of first resistors connected to a voltage source and the series of diode-connected FETs. Additionally, one or more second resistors are connected to the series of diode-connected FETs and to ground. In an embodiment method, the total number of the diode-connected FETs and the total number of the resistors, including the first and second series of resistors, are selected. The total number of the second resistors is then determined according to a defined relation between the selected total number of diode-connected FETs and the total number of resistors.

A single-ended mixer having a mismatched, high termination impedance is disclosed. The termination impedance can be mismatched by at least one order of magnitude higher than the standard impedance of a given design environment, such as a 50 Ohm environment for a radio frequency (RF) circuit. The termination impedance can be provided in close physical proximity to the mixer core of the single-ended mixer to allow a suitable bandwidth of operation.