The multi-modal imaging system, in particular for brain imaging, comprising a pump signal generator which emits at least one pump signal in the radio frequency (RF)-range with a first power P1 and a second power P2, a wireless detection unit, which comprises at least one parametric resonator circuit with multiple resonance modes, wherein the at least one parametric resonator circuit comprises at least two varactors, at least one capacitor and at least one inductance, wherein, in a first detection mode, the pump signal, having a first power P1, induces a first pump current in the at least one parametric resonator circuit, wherein the at least one parametric resonator circuit is operated below its oscillation threshold and generates a first output signal by amplifying a first input signal, which is provided due to a magnetic-resonance (MR) measurement, wherein an external receiving device receives the first output signal, wherein, in a second detection mode, the pump signal, having a second power P2, induces a second pump current in the at least one parametric resonator circuit, wherein the at least one parametric resonator circuit is operated above its oscillation threshold and generates a second output signal, wherein the second output signal is modulated with a second input signal, wherein the second input signal is provided by at least one neuronal probe device, connected to the at least one parametric resonator circuit, wherein the external receiving device receives the second output signal.

In a first clock frequency multiplier, multiple injection-locked oscillators (ILOs) having spectrally-staggered lock ranges are operated in parallel to effect a collective input frequency range substantially wider than that of a solitary ILO. After each input frequency change, the ILO output clocks may be evaluated according to one or more qualifying criteria to select one of the ILOs as the final clock source. In a second clock frequency multiplier, a flexible-injection-rate injection-locked oscillator locks to super-harmonic, sub-harmonic or at-frequency injection pulses, seamlessly transitioning between the different injection pulse rates to enable a broad input frequency range. The frequency multiplication factor effected by the first and/or second clock frequency multipliers in response to an input clock is determined on the fly and then compared with a programmed (desired) multiplication factor to select between different frequency-divided instances of the frequency-multiplied clock.

A digital quadrature modulator holds local oscillator circuitry configured to provide local oscillator signals, and local oscillator polarity logic circuitry configured to select an In-phase and a Quadrature local oscillator signal according to a sign bit of an In-phase control word and a sign bit of a Quadrature control word, respectively. The modulator holds a number of local oscillator control logic circuits, each configured to generate a conditioned signal by gating one or both of the selected local oscillator signals according to values of the In-phase control word and/or values of the Quadrature control word. The modulator has one or more sets of switched-capacitor units, where each unit has an output provided by an output capacitor, and where a signal at the input side of the output capacitor is controlled by a conditioned signal. The outputs of at least two of the switched-capacitor units are combined in a common node.

A method includes receiving a series of radio frequency (RF) signals, where, from RF signal to RF signal of the series of RF signals, a carrier frequency is changed in accordance with a frequency hopping pattern. The method further includes, while receiving the series of RF signals, sensing an environmental condition by, for a frequency hop of at least some frequency hops of the frequency hopping pattern, adjusting a characteristic of a wireless sensor to maintain proximal alignment of a resonant frequency of the wireless sensor with the carrier frequency corresponding to a present frequency of the at least some frequency hops and generating a value to represent the adjustment of the characteristic, where a set of values is generated for the at least some frequency hops and where the set of values is used to determine a sensed value of the environmental condition.

Techniques are disclosed implementing a tunable transformer with additional taps in at least one of the three coils. The tunable transformer enables the resonant frequency within RF transceiver matching networks to be adjusted without substantially impacting the output power at resonance. The tunability of the transformer is partially driven by the insertion of additional coils within the transformer, which are selectively switched and may be further coupled with a tunable capacitance. The tunability of the transformer is further driven via the use of at least one multi-tap transformer coil, which allows electronic components to be coupled to different coil taps to thereby facilitate an adjustable DC inductance. Doing so counteracts changes in mutual inductance between the non-switched coils, and facilitates the stabilization of output power with shifts in resonant frequency.

A method includes receiving, by an RF receiving circuit of a passive wireless sensor of a wireless communication system, an RF signal. When a sensing element of the passive wireless sensor is exposed to an environmental condition, the method further includes affecting, by the sensing element, resonant frequency of the RF receiving circuit. The method further includes determining, by a processing module of the passive wireless sensor, a first value for an adjustable element for a known environmental condition, determining a second value for the adjustable element for an unknown environmental condition, determining a difference between the first and second values that correspond to a change, generating a coded value representative of the change, and transmitting the coded value. The method further includes receiving, by a second processing module of a sensor computing device of the wireless communication system, the coded value and determining a sensed environmental condition.

A radio frequency (RF) circuit includes a tank circuit having a selectively variable impedance. The RF circuit further includes a tuning circuit adapted to dynamically vary the impedance of the tank circuit, and to develop a first quantized value representative of a change to impedance of the tank circuit. The RF circuit further includes a detector circuit adapted to develop a second quantized value representative of a field strength of a received RF signal.

An exemplary tunable circuit includes an inductor coupled to a node and a first capacitor coupled to the node. The tunable circuit also includes a variable capacitor coupled to the node, such that a total capacitance of the tunable circuit depends on a fixed capacitance of the first capacitor and a variable capacitance of the variable capacitor. In an example, the inductor and the first capacitor are both included in a passive device and the variable capacitor is in a semiconductor device. The variable capacitor allows the total capacitance to be modified for the purpose of, for example, calibrating the capacitance to account for manufacturing variations, and/or adjusting to a frequency range of operation used by wireless devices in a region of the world. The first capacitor may be a higher quality capacitor providing a larger portion of the total capacitance than the variable capacitor.

An exemplary tunable circuit includes an inductor coupled to a node and a first capacitor coupled to the node. The tunable circuit also includes a variable capacitor coupled to the node, such that a total capacitance of the tunable circuit depends on a fixed capacitance of the first capacitor and a variable capacitance of the variable capacitor. In an example, the inductor and the first capacitor are both included in a passive device and the variable capacitor is in a semiconductor device. The variable capacitor allows the total capacitance to be modified for the purpose of, for example, calibrating the capacitance to account for manufacturing variations, and/or adjusting to a frequency range of operation used by wireless devices in a region of the world. The first capacitor may be a higher quality capacitor providing a larger portion of the total capacitance than the variable capacitor.

Devices and methods for improving voltage handling and/or bi-directionality of stacks of elements when connected between terminals are described. Such devices and method include use of symmetrical compensation capacitances, symmetrical series capacitors, or symmetrical sizing of the elements of the stack.