A filter stage system, includes a continuous time baseband filter comprising a feedback loop that employs at least one first impedance node and at least one second impedance node, wherein the at least one first impedance node has a higher impedance than the at least one second impedance node, and wherein the at least one first impedance node provides a dominant pole and the at least one second impedance node provides a non-dominant pole, and wherein the continuous time baseband filter generates a filtered current, and a mirroring component mirrors the filtered current to an output.

One or more systems, devices and/or methods of use provided herein relate to a baseband filter that can be used in a current-mode end-to-end signal path. The current-mode end-to-end signal path can include a digital to analog converter (DAC) operating in current-mode and an upconverting mixer, operating in current-mode and operatively coupled to the DAC. In one or more embodiments, a device used in the signal path can comprise a baseband filter that receives an input current and outputs an output current. The baseband filter can comprise a feedback loop component having an active circuit branch and a passive circuit branch coupled in a loop. A mirroring device can be coupled to the feedback loop component and can provide an output of the device. Selectively activating the mirroring device can vary gain, such as of the mirroring device.

A semiconductor device including a first inverter circuit connected in parallel to a crystal vibrating element; a second inverter circuit connected to the first inverter circuit so as to share an input therewith, and outputting an oscillation signal; and a wave filter connected to the second inverter circuit and having a passband that is determined in advance and includes an oscillation frequency of the oscillation signal.

In one aspect, a time division interleaving band-pass filter can be used in voice activity detection, which operates at different central frequencies in respective intervals of a predetermined period of time. The band-pass filter circuitry includes multiple band-pass filtering channels sharing a common transistor circuit, bias circuit and current mirror circuit. The multiple band-pass filtering channels operate in a time division interleaving manner, which enables the sharing of the common set of band-pass filter circuitry components. Thus, the present invention allows a reduced chip area as the area does not increase proportionally with the number of filtering channels. The invention also mitigates the influence of transistor fabrication variations on the filter's central frequencies. Moreover, pulse durations t.sub.i are additionally introduced to the determination of the central frequencies, dispensing with the need for matching of current mirror circuits and transistors and resulting in higher accuracy of the band-pass filter's central frequencies.

A circuit includes a filter, a first inverter, and a second inverter. The filter is coupled to an input of the first inverter. The second inverter includes an input and an output. The input of the second inverter is coupled to the output of the first inverter. The output of the second inverter is coupled to the input of the first inverter.

A circuit includes a filter, a first inverter, and a second inverter. The filter is coupled to an input of the first inverter. The second inverter includes an input and an output. The input of the second inverter is coupled to the output of the first inverter. The output of the second inverter is coupled to the input of the first inverter.

A circuit has a first window comparator determining whether a signal at a first input has a voltage higher than a first threshold but lower than a second threshold, and a second window comparator determining whether a signal at a second input has a voltage higher than the first threshold but lower than the second threshold. A logic circuit generates pulses in response to either the first window comparator determining that the signal at the first differential input has a voltage higher than the first threshold but lower than the second threshold or the second window comparator determining that the signal at the second input has a voltage higher than the first threshold but lower than the second threshold. A filter circuit receives the pulses from the logic circuit and generates a flag indicating that the signal is invalid, based upon pulses received from the logic circuit.

A method and apparatus are described to implement a bandpass filter in a current mode logic (CML) stage of a clock tree in an electronic system. The bandpass filter has a bandpass filter transfer function to attenuate frequencies lower than and higher than a carrier frequency. The bandpass filter uses adjustable active inductors and capacitive source degeneration. Adjustable resistors may be controlled to move a peak frequency of the bandpass filter transfer function to a higher or lower frequency. The adjustable active inductors and capacitive degeneration may consist of field effect transistors.

A low power crystal oscillator is provided. The crystal oscillator includes a gain control stage, a filter stage, and an output stage. The gain control stage includes an input coupled at a first oscillator terminal configured and arranged for connection to a first terminal of a crystal. The filter stage includes an input coupled to an output of the gain control stage. The output stage includes a first transistor having a first current electrode coupled at a second oscillator terminal configured and arranged for connection to a second terminal of the crystal and a control electrode coupled to receive a voltage signal at the first oscillator terminal and a first bias voltage.

Systems and methods for improving source-follower-based Sallen-Key architectures are disclosed. In particular, systems and methods for circumventing the non-idealities associated with source-follower-based Sallen-Key biquad filters when used in either baseband signal or radiofrequency paths. The systems and methods disclosed herein present power-efficient, cost-efficient solutions that can be implemented in a reduced area of a circuit.