An active filter comprising an operational amplifier, and a controller configured to control the bandwidth of the operational amplifier based on a filter cutoff frequency setting and/or a noise performance setting.

An active electromagnetic interference filter comprising an adjustable shunt impedance circuit, the adjustable shunt impedance circuit comprising a noise sensing branch that senses input noise and provides a noise voltage representative of the sensed noise, and an operational amplifier stage configured to generate, at an injection branch, an injection current based on the noise voltage.

Various embodiments relate to a method for calibration of a center frequency of a BPF in an FSK transceiver, the method including the steps of filtering a carrier frequency signal by the BPF to produce a filtered signal, detecting, by a phase-frequency detector (PFD), a difference in phase between the carrier frequency signal and the filtered signal from the BPF, sweeping a calibration code of the BPF, detecting a transition in the sign of the phase difference and capturing a calibration code associated with the transition in the sign of the phase difference for calibration of the BPF.

A notch filter includes a first inductor coupled between an input node and an output node, a dual-resonator structure coupled between the input node and the output node, and a second inductor coupled between the dual-resonator structure and ground, and a bandpass filter includes a capacitor coupled between an input node and an output node, and a dual-resonator structure coupled between the input node, the output node, and ground.

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 merging 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.

The object is to simplify the configuration of a filter in a reception apparatus. The reception apparatus includes a filter. The filter provided in the reception apparatus selects a signal transmission characteristic that is one of a band stop characteristic or a low pass characteristic. Further, selection of the signal transmission characteristic in the filter provided in the reception apparatus is performed in response to a desired signal and an interference signal. In the filter provided in the reception apparatus, passage of the desired signal and attenuation of the interference signal based on the selected signal transmission characteristic are executed.

The object is to simplify the configuration of a filter in a reception apparatus. The reception apparatus includes a filter. The filter provided in the reception apparatus selects a signal transmission characteristic that is one of a band stop characteristic or a low pass characteristic. Further, selection of the signal transmission characteristic in the filter provided in the reception apparatus is performed in response to a desired signal and an interference signal. In the filter provided in the reception apparatus, passage of the desired signal and attenuation of the interference signal based on the selected signal transmission characteristic are executed.

A compensation filter and a method for activating a compensation filter are disclosed. In an embodiment a compensation filter includes a power supply line, an electrical amplifier, an output-coupling circuit between the power supply line and an input of the electrical amplifier, an input-coupling circuit between an output of the amplifier and the power supply line, and a time switch. The time switch is connected in series with the input-coupling circuit between the output of the amplifier and the power supply line.

This application relates to time-encoding modulators (TEMs). A TEM receives an input signal (S.sub.IN) and outputs a time-encoded output signal (S.sub.OUT). A filter arrangement receives the input signal and also a feedback signal (S.sub.FB) from the TEM output, and generates a filtered signal (S.sub.FIL) based, at least in part, on the feedback signal. A comparator receives the filtered signal and outputs a time-encoded signal (S.sub.PWM) based at least in part on the filtered signal. The time encoding modulator is operable in a first mode with the filter arrangement configured as an active filter and in a second mode with the filter arrangement configured as a passive filter. The filter arrangement may include an op-amp, capacitance and switch network. In the first mode the op-amp is enabled, and coupled with the capacitance to provide the active filter. In the second mode the op-amp is disabled and the capacitance coupled to a signal path for the feedback signal to provide a passive filter.

A coupling module can be used to communicate high speed signals between an optical transceiver and a processing module of an optical communication device, such as an optical line termination (OLT) or an optical network unit (ONU). The coupling module can adjust the common mode voltage level of a differential signal output by the optical transceiver to the common mode voltage level required by the processing module. In addition, the coupling module splits each of the differential output signals from the optical transceiver and passes the split signals to both a high-pass filter and a low-pass filter that are connected in parallel. The outputs of the high-pass filter and the low-pass filter from different paths of the differential signal are cross-coupled and combined to provide a differential signal to the processing module.