An IF filter band-limits an intermediate frequency signal outputted from a mixer. An AFC unit controls the oscillation frequency of a PLL so that the frequency of the intermediate frequency signal is a predetermined frequency. When the AFC unit controls the oscillation frequency of the PLL, a band control unit controls the passing characteristic of the IF filter to the passing characteristic of a wide band, and after the completion of the control, controls the passing characteristic of the IF filter to the passing characteristic of a narrow band. A frequency correction unit refers to a filter information storage unit, and corrects the oscillation frequency controlled by the AFC unit according to the difference between the center frequency of the passband of the passing characteristic of the wide band and the center frequency of the passband of the passing characteristic of the narrow band.

A resonator and resonator method are provided. The resonator includes an inductor, a capacitor, and a switch configured to maintain energy in at least one of the inductor and the capacitor for a select period of time and to enable variability of energy in the at least one of the inductor and the capacitor for another period of time, to set a resonating frequency of the inductor and the capacitor.

A voltage divider is described. The voltage divider comprises a pair of input nodes for receiving an input signal; a pair of output nodes configured to generate an output signal; a first capacitor having a first terminal coupled to a first output node of the pair of output nodes and a second terminal coupled to a second output node of the pair of output nodes; and a second capacitor having first terminal and a second terminal; a bypass switch having a first terminal coupled to the first terminal of the second capacitor and a second terminal coupled to the second terminal of the second capacitor; and a charge sharing switch coupled to the second terminal of the second capacitor; wherein the bypass switch and the charge sharing switch enable the sharing of charge between the first capacitor and the second capacitor.

A magnet-free non-reciprocal device realized using modulated filters. The device includes one or more filters in one or more branches, where each branch connects two ports or a port and a central node. The poles and zeros of each of the first, second and third filters are modulated in time such that degenerate modes at each pole and zero is split thereby destructively interfering at one or more output ports and adding up at another output port allowing non-reciprocal transmission, isolation and/or non-reciprocal phase shift. The device is able to realize a magnet-free full-duplex communication scheme implementing a magnet-free circulator for radio frequency cancellation or a magnet-free isolator or gyrator.

A comparator offset calibration system having a comparator offset evaluator and a switched-capacitor network is disclosed, which is in an analog and digital dual domain structure. The comparator offset evaluator receives digital data from an analog-to-digital conversion module, evaluates an offset of a comparator of the analog-to-digital conversion module based on the received digital data, and outputs an evaluated result. The switched-capacitor network processes the evaluated result to generate a control signal. The analog-to-digital conversion module adjusts the offset of the comparator according to the control signal.

Various embodiments relate to an analog-to-digital converter (ADC). The ADC may include a first channel including a first delta-sigma loop filter and a second channel including a second delta-sigma loop filter. Each of the first delta-sigma loop filter and the second delta-sigma loop filter may include a first integrator and a quantizer having an input coupled to an output of the first integrator. Each of the first delta-sigma loop filter and the second delta-sigma loop filter may also include a first summing node having an output coupled to an input of the first integrator, and a feedforward path from an input of the delta-signal loop filter to a first input of the first summing node. Further, each of the first delta-sigma loop filter and the second delta-sigma loop filter may include a first feedback path from an output of the quantizer to a second input of the first summing node.

An aspect includes a filtering method including operating a first filter to filter a first input signal to generate a first output signal; operating a second filter to filter a second input signal to generate a second output signal; and selectively coupling at least a portion of the second filter with the first filter to filter a third input signal to generate a third output signal. Another aspect includes a filtering method including operating switching devices to configure a filter with a first set of pole(s); filtering a first input signal to generate a first output signal with the filter configured with the first set of pole(s); operating the switching devices to configure the filter with a second set of poles; and filtering a second input signal to generate a second output signal with the filter configured with the second set of poles.

Integrator circuits comprising switched capacitors, non-switched capacitors, and an op amp. One embodiment is directed to an integrator circuit comprising an op amp having an inverting input, a non-inverting input, an inverting output and a non-inverting output, a first sampling capacitor and a first feedback capacitor, and a first non-switched capacitor. The first feedback capacitor is coupled between the inverting input and the non-inverting output of the op amp, and the first non-switched capacitor is coupled between the negative integrator input and the inverting input of the op amp. During a sampling phase, a positive integrator input is coupled to the first sampling capacitor, and during an integration phase, a charge sampled across the first sampling capacitor during the sampling phase is transferred to the first integration capacitor.

A variable resistor may be coupled between a reference voltage source and components of an integrated circuit to reduce issues relating to thermal noise from a reference voltage signal generated by the reference voltage source. The variable resistor may be set to a low level during a first time period and a high level during a second time period, in which the time periods correspond to a sampling period of a switched-capacitor circuit. The low resistance time period may allow quick settling of an input reference voltage signal, whereas the high resistance time period may reduce a bandwidth of noise on a sampling capacitor coupled to the reference voltage signal. The variable resistor and switched-capacitor network may be used in an analog-to-digital converter (ADC), such as in audio circuits.

A system and method for providing asymmetrical filtering to improve performance in the presence of wideband interference is herein disclosed. According to one embodiment, a method for a global navigation satellite system (GNSS) receiver includes detecting wideband interference in a received target GNSS signal, and applying an asymmetric filter to the received target GNSS signal to mitigate the detected wideband interference.