An apparatus and method of removing common mode noise in the case of measuring a biosignal using a capacitive coupling active electrode (CCE) is provided. A frequency band of a common mode signal may interact with a shield voltage and thus, a frequency band of a biosignal may be compensated for.

A control circuit for suppressing electromagnetic interference signal has an input and an output and a variable gain filter circuit with a first gain factor that is variable. The variable gain filter circuit receives a signal indicative of an electromagnetic interference signal and outputs a signal to a controlled signal source, which a second gain factor. The control circuit also has a controller operably connected to the variable gain filter circuit. The controller receives a signal indicative of an output signal at the output of the control circuit and outputs a control signal to the variable gain filter circuit. The control signal is based on the signal indicative of the output signal at the output of the control circuit, and the control signal controls the first gain factor and reduces the electromagnetic interference signal.

This application relates to an independent active electromagnetic interference filter module. In one aspect, the filter module includes a first element group including a noise sensing unit provided to sense electromagnetic noise, and a second element group including a compensating unit provided to generate a compensation signal for the electromagnetic noise. The first group and the second group may be respectively mounted on different substrates. According to some embodiments, the filter module can reduce a volume of each element constituting an electromagnetic interference filter module, implement a single modularization of a compact structure. The filter module can also improve electromagnetic interference noise reduction performance and a manufacturing method thereof.

In accordance with a first aspect of the present disclosure, an active RC-type filter is provided, comprising: an input, an output and a signal path between said input and output; at least one capacitor bank and at least one resistor bank, wherein said capacitor bank and resistor bank are integrated into the signal path; wherein the resistor bank comprises a plurality of resistor ladders; wherein each one of said resistor ladders comprises a plurality of resistors connected in series; wherein each one of said resistors has an input node configured to be coupled selectively to the signal path through one of a plurality of controllable switches; and wherein said resistor ladders have output nodes directly coupled to each other and to the signal path. In accordance with a second aspect of the present disclosure, a corresponding method of implementing an active RC-type filter is conceived.

The present application provides a window function processing module including an integrating circuit, configured to receive an integrating input signal, the integrating circuit comprising an operational amplifier; an integrating capacitor, coupled to an output terminal and a first input terminal of the operational amplifier; and an adjustable impedance module, coupled between the first input terminal of the operational amplifier and an integrating input terminal of the integrating circuit, wherein the adjustable impedance module is controlled by at least one control signal to adjust an impedance value of the adjustable impedance module; and a control unit, coupled to the integrating circuit, configured to generate the at least one control signal according to a window function, to adjust the integration gain of the integrating circuit, such that the integrating output signal is related to an operation result of the integrating input signal and the window function.

A differential elliptic filter circuit includes: a differential amplifier, feedback and feedforward paths. An upper pair and a lower pair of inverting feedback paths couple a corresponding one the differential signal outputs of the amplifier to an inverting one of a pair of inputs of the amplifier, to provide two complex conjugate poles, and establish upper and lower virtual grounds at the amplifier inputs. Upper and lower inverting feedforward paths couple corresponding passive nodes of the upper and lower pairs of inverting feedback paths to respectively the lower and upper virtual grounds to provide two zeros of the circuit. The upper and lower non-inverting feedforward paths couple an upper and lower one of a pair of differential signal inputs of the circuit to respectively the upper and lower virtual grounds to enable positioning of the two zeros of the circuit on an imaginary axis of a pole-zero plot.

According to at least one aspect, a filter network is provided. The filter network comprises: an active filter comprising an amplifier (e.g., an operational amplifier), wherein the active filter is configured to add at least one member selected from the group consisting of a pole and a zero to a transfer function of the filter network; a passive filter coupled to the active filter and configured to add at least one pole to the transfer function of the filter network; and a non-inverting amplifier (e.g., a voltage buffer) having an input coupled to the passive filter and an output coupled to the active filter.

A sensor device includes: first sensors; second sensors which form capacitances with the first sensors; a sensor transmitter connected to the first sensors, where the sensor transmitter supplies driving signals to the first sensors; and a sensor receiver connected to the second sensors, where the sensor receiver receives sensing signals from the second sensors, and the sensor receiver includes a band pass filter which filters the sensing signals. The band pass filter includes: a first integrator including a first amplifier; a first high pass filter converter connected to a first input terminal, a second input terminal and a first output terminal of the first amplifier, where the first high pass filter converter time-divisionally provides N high pass filter conversion paths; and a first gain auxiliary component connected to the first input terminal and the first output terminal of the first amplifier while the first integrator performs an integral function.

A first and second input tone are applied to a continuous-time complex filter within an integrated circuit. The magnitude of the output of the filter at the frequency of each of the first and second input tones are measured and compared to determine the value of a filter tuning control signal. A tuning control signal is applied to the filter with the determined value to tune the filter.

A mixer with a filtering function and a method for linearization of the mixer are provided. The mixer includes at least one amplifier, a transconductance device and a feedback network. The at least one amplifier is configured to output a filtered voltage signal according to an input voltage signal. The transconductance device is coupled to the at least one amplifier, and is configured to generate a filtered current signal according to the filtered voltage signal. The feedback network is coupled between any output terminal among at least one output terminal of the transconductance device and an input terminal of the at least one amplifier. More particularly, the mixer is configured to output a modulated signal according to the filtered current signal.