An analog front end system can include a filter bypass switch connected in a boot-strapped configuration to pull a control terminal of the filter bypass switch above or below a supply voltage. Using bootstrapped switches can allow both the charge injection and capacitive coupling of the bypass switches of a differential anti-alias filter (AAF) to be common mode. A differential input signal of the ADC is not affected by the charge injection and capacitive coupling of the bypass switches in the AAF filter to a first order.

In a conventional sensor signal detection device, an amplifier and an anti-alias analogue filter are essential for AD conversion of a small sensor output signal. The present application provides a sensor signal detection device that inputs an electric signal output from a sensor to a commercially available AD converter directly or via a means for converting the electric signal into voltage, outputs the electric signal via a digital filter, and realizes sufficient resolution and noise characteristics without using an amplifier and an analogue filter which have conventionally been considered to be essential, by devising conditions, etc., of an AD conversion clock and digital filter.

A method of detecting an obtruding signal in a radio receiver, a receiver and a computer program are disclosed. The receiver has a mixer arranged to mix a received signal to an analog baseband signal at or close to zero-frequency, a filter arranged to low-pass filter said analog baseband signal, and an analog-to-digital converter arranged to sample said filtered analog baseband signal at a sample frequency such that a digital baseband signal is formed. The method comprised receiving a radio frequency signal, mixing the radio frequency signal to the analog baseband signal at or close to zero-frequency, low-pass filtering said analog baseband signal, and analog-to-digital converting said filtered analog baseband signal at an over sample frequency such that a digital baseband signal is formed. The method further comprises frequency translating the digital baseband signal around a Nyquist frequency being based on a nominal sample frequency, the nominal sample frequency being a fraction of the oversampling frequency according to the oversampling rate, to form a translated digital baseband signal such that signal content of the digital baseband signal around zero frequency will be translated to around the nominal sample frequency and vice versa in the translated digital baseband signal, determining a first signal level at zero frequency of the digital baseband signal and a second signal level at zero frequency of the translated digital baseband signal, detecting an obtruding signal based on a relation between the first and second signal levels, and outputting an obtruding signal state signal.

An outphasing power amplifying device includes a switching signal generating circuit configured to generate a switching pulse signal for switching a class-D power amplifier from two types of sinusoidal wave generated based on amplitude and phase of a modulated wave to be transmitted. The switching signal generating circuit includes: a sin calculation unit and a cos calculation unit for converting phase information of the two types of sinusoidal wave into a quadrature format; a DA converter for converting the quadrature-format phase information; a first filter for removing an aliasing component from the analogue signal; an analogue quadrature modulator for generating a sinusoidal wave from the analogue signals by using a local signal; a second filter for allowing a radio frequency and a component in the vicinity thereof to pass therethrough; and a comparator for converting the sinusoidal wave into a switching pulse signal by comparison with a reference voltage.

A system comprises an analog front end (AFE), an analog-to-digital converter (ADC), and alias detection circuitry. The AFE may be operable to receive an analog signal via a communication medium, wherein a first frequency band of the analog signal is occupied by an OFDM symbol and a second frequency band of the analog signal is occupied by first aliases generated during digital-to-analog conversion of the OFDM symbol. The ADC is operable to digitize the particular band of the analog signal to generate a digital signal, wherein, during the digitization, aliasing of the first aliases results in second aliases which fall into the first frequency band. The alias detection circuitry is operable to detect the second aliases in the first frequency band of the digital signal, and process the digital signal based on the detected second aliases to generate an output signal.

A circuit comprises a driver circuit, a processing circuit, and a control circuit. The driver circuit has a first frequency control input and a driver output. The processing circuit has a sense input, a second frequency control input, and a parameter output. And the control circuit has a first frequency control output and a second frequency control output, the first frequency control output coupled to the first frequency control input, and the second frequency control output coupled to the second frequency control input.

A system comprises an analog front end (AFE), an analog-to-digital converter (ADC), and alias detection circuitry. The AFE may be operable to receive an analog signal via a communication medium, wherein a first frequency band of the analog signal is occupied by an OFDM symbol and a second frequency band of the analog signal is occupied by first aliases generated during digital-to-analog conversion of the OFDM symbol. The ADC is operable to digitize the particular band of the analog signal to generate a digital signal, wherein, during the digitization, aliasing of the first aliases results in second aliases which fall into the first frequency band. The alias detection circuitry is operable to detect the second aliases in the first frequency band of the digital signal, and process the digital signal based on the detected second aliases to generate an output signal.

A method may include, for a signal path comprising a passive antialiasing filter sampled by a switched-capacitor front-end, monitoring a change of a first impedance of a resistor of the passive antialiasing filter responsive to an environmental condition relative to a second impedance of a switched capacitor of the switched-capacitor front end and compensating the signal path for a change in gain of the signal path resulting from the change of the first impedance.

An outphasing power amplifying device includes a switching signal generating circuit configured to generate a switching pulse signal for switching a class-D power amplifier from two types of sinusoidal wave generated based on amplitude and phase of a modulated wave to be transmitted. The switching signal generating circuit includes: a sin calculation unit and a cos calculation unit for converting phase information of the two types of sinusoidal wave into a quadrature format; a DA converter for converting the quadrature-format phase information; a first filter for removing an aliasing component from the analogue signal; an analogue quadrature modulator for generating a sinusoidal wave from the analogue signals by using a local signal; a second filter for allowing a radio frequency and a component in the vicinity thereof to pass therethrough; and a comparator for converting the sinusoidal wave into a switching pulse signal by comparison with a reference voltage.

An analog front end system can include a filter bypass switch connected in a boot-strapped configuration to pull a control terminal of the filter bypass switch above or below a supply voltage. Using bootstrapped switches can allow both the charge injection and capacitive coupling of the bypass switches of a differential anti-alias filter (AAF) to be common mode. A differential input signal of the ADC is not affected by the charge injection and capacitive coupling of the bypass switches in the AAF filter to a first order.