An example apparatus includes a polyphase transconductance-capacitor filter. The polyphase filter includes a DC bias voltage node, a plus in-phase filter unit, a minus in-phase filter unit, a plus quadrature-phase filter unit, and a minus quadrature-phase filter unit. Each filter unit respectively includes an input node, an output node, and a control node. The polyphase filter also includes a plus in-phase switch and a minus in-phase switch. The plus in-phase switch is coupled to the control node of the plus in-phase filter unit, the DC bias voltage node, and the input node of one or both of the plus quadrature-phase filter unit and the minus quadrature-phase filter unit. The minus in-phase switch is coupled to the control node of the minus in-phase filter unit, the DC bias voltage node, and the input node of one or both of the plus quadrature-phase filter unit and the minus quadrature-phase filter unit.

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.

An example apparatus includes a polyphase transconductance-capacitor filter. The polyphase filter includes a DC bias voltage node, a plus in-phase filter unit, a minus in-phase filter unit, a plus quadrature-phase filter unit, and a minus quadrature-phase filter unit. Each filter unit respectively includes an input node, an output node, and a control node. The polyphase filter also includes a plus in-phase switch and a minus in-phase switch. The plus in-phase switch is coupled to the control node of the plus in-phase filter unit, the DC bias voltage node, and the input node of one or both of the plus quadrature-phase filter unit and the minus quadrature-phase filter unit. The minus in-phase switch is coupled to the control node of the minus in-phase filter unit, the DC bias voltage node, and the input node of one or both of the plus quadrature-phase filter unit and the minus quadrature-phase filter unit.

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 present disclosure relates to a concept of nonlinear signal processing which may be used for predistortion for RF power amplifiers. The concept includes generating time variant filter coefficients for a linear filter circuit based on a nonlinear mapping of an input signal, and filtering the input signal with the linear filter circuit using the time variant filter coefficients in order to generate a filtered output signal. Thus, it is proposed to implement a non-linear filter by a time-varying linear filter where the time-varying coefficients are derived from the input signal.

A calibration device includes a signal generator and a processor. The signal generator is configured to provide an input signal to a filter circuit, wherein the filter circuit has a real time constant and is configured to receive the input signal to output an output signal. The processor is configured to calculate a real gain according to the output signal and the input signal, compare the real gain with a target gain to obtain a comparison result and determine whether to adjust the real time constant of the filter circuit according to the comparison result. The present disclosure also provides a calibration method.

Systems, devices, and methods including a first band-pass filter configured to receive and filter a detector signal where the first band-pass filter has a central frequency of 2f; a second band-pass filter configured to receive and filter the detector signal where the second band-pass filter has a central frequency of 1f; a first logarithmic amplifier (Log Amp) configured to apply the filtered detector signal from the first band-pass filter; a second Log Amp configured to apply the filtered detector signal from the second band-pass filter; a differential amplifier configured to subtract the applied signal from the first Log Amp from the applied signal from the second Log Amp; and an Anti-Log Amplifier configured to determine an inverse logarithm of the subtracted signal from the differential amplifier.

A calibration device includes a signal generator and a processor. The signal generator is configured to provide an input signal to a filter circuit, wherein the filter circuit has a real time constant and is configured to receive the input signal to output an output signal. The processor is configured to calculate a real gain according to the output signal and the input signal, compare the real gain with a target gain to obtain a comparison result and determine whether to adjust the real time constant of the filter circuit according to the comparison result. The present disclosure also provides a calibration method.

There is provided wireless transmitter that includes a poly phase filter (PPF) configured to receive an input differential intermediate frequency (IF) signal and to generate an in-phase differential IF signal and a quadrature differential IF signal. The wireless transmitter further includes a transformer-based circuit configured to receive an input differential local oscillator (LO) signal and to generate an in-phase differential LO signal and a quadrature differential LO signal based on the input differential LO signal. In addition, the wireless transmitter includes a mixer configured to multiplicatively mix the in-phase differential IF signal with the quadrature differential LO signal to produce a first RF signal component and to multiplicatively mix the quadrature differential IF signal with the in-phase differential LO signal to produce a second RF signal component, the mixer further configured to provide a differential RF signal comprising a (filtered or unfiltered) combination of the first RF signal component and the second RF signal component. Furthermore, the wireless transmitter includes an amplification stage configured to amplify the differential RF signal, the amplification stage comprising a driver stage and a power amplifier stage.

There is provided wireless transmitter that includes a poly phase filter (PPF) configured to receive an input differential intermediate frequency (IF) signal and to generate an in-phase differential IF signal and a quadrature differential IF signal. The wireless transmitter further includes a transformer-based circuit configured to receive an input differential local oscillator (LO) signal and to generate an in-phase differential LO signal and a quadrature differential LO signal based on the input differential LO signal. In addition, the wireless transmitter includes a mixer configured to multiplicatively mix the in-phase differential IF signal with the quadrature differential LO signal to produce a first RF signal component and to multiplicatively mix the quadrature differential IF signal with the in-phase differential LO signal to produce a second RF signal component, the mixer further configured to provide a differential RF signal comprising a (filtered or unfiltered) combination of the first RF signal component and the second RF signal component. Furthermore, the wireless transmitter includes an amplification stage configured to amplify the differential RF signal, the amplification stage comprising a driver stage and a power amplifier stage.