A tunable slope equalizer comprising a waveguide (e.g., rectangular waveguide) and posts (e.g., cylindrical posts) configured to move inside the internal cavity of the waveguide is presented. The degree of depth the posts may be inserted into the cavity of the waveguide may determine the orientation of the frequency response slope, e.g., positive or negative, and the maximum (or approximately maximum) insertion loss at minimum (or approximately minimum) or maximum (or approximately maximum) operating frequency, respectively. Being a mechanical device, the tunable slope equalizer may be fabricated at a relatively higher level of precision, leading to lower variances in performance over production.

A dual-mode signal amplifying circuit includes: a first and a second input terminals for receiving differential input signals; two output terminals for providing differential output signals; a first through a third current sources; a first switch positioned between the first current source and a first node, and controlled by the first input terminal; a second switch positioned between the first current source and a second node, and controlled by the second input terminal; a third switch positioned between the first node and a fixed-voltage terminal, and controlled by a third node; a fourth switch positioned between the second node and a fixed-voltage terminal and controlled by the third node; a fifth switch positioned between the second current source and a fixed-voltage terminal, and controlled by the first node; and a sixth switch positioned between the third current source and a fixed-voltage terminal, and controlled by the second node.

A dual-mode signal amplifying circuit includes: a first and a second input terminals for receiving differential input signals; two output terminals for providing differential output signals; a first through a third current sources; a first switch positioned between the first current source and a first node, and controlled by the first input terminal; a second switch positioned between the first current source and a second node, and controlled by the second input terminal; a third switch positioned between the first node and a fixed-voltage terminal, and controlled by a third node; a fourth switch positioned between the second node and a fixed-voltage terminal and controlled by the third node; a fifth switch positioned between the second current source and a fixed-voltage terminal, and controlled by the first node; and a sixth switch positioned between the third current source and a fixed-voltage terminal, and controlled by the second node.

Provided is an amplification circuit for amplifying an input signal. The amplification circuit includes an input stage including an input matching circuit that receives the input signal and an input attenuation circuit that attenuates a gain for the input signal outside an operating frequency band of the amplification circuit, a transistor that amplifies the input signal provided from the input stage, and an output stage including an output matching circuit that receives a signal amplified by the transistor and an output attenuation circuit that attenuates the gain for the input signal outside the operating frequency band of the amplification circuit, and the input attenuation circuit includes a first resistor and a second resistor that are connected to a ground voltage, a first passive element connected between the input matching circuit and the second resistor, and a second passive element connected between the first passive element and the first resistor.

A system and method in an audio signal electrical circuit including a feedback loop with a digital filter coupled to a current digital to analog converter (IDAC) includes providing an output signal from the IDAC to analog elements of the audio signal electrical circuit, the output signal from the IDAC based upon a reference signal input to the IDAC when an output of the digital filter is not input to the IDAC. The system and method also include comparing an output signal of the audio signal electrical circuit to a reference, and calibrating the audio signal electrical circuit to correspond the output signal of the audio signal electrical circuit to the reference. Calibration of the audio signal electrical circuit enables more precise control of a cut-off frequency of a microphone signal when the output of the digital filter is input to the IDAC.

A system and method in an audio signal electrical circuit including a feedback loop with a digital filter coupled to a current digital to analog converter (IDAC) includes providing an output signal from the IDAC to analog elements of the audio signal electrical circuit, the output signal from the IDAC based upon a reference signal input to the IDAC when an output of the digital filter is not input to the IDAC. The system and method also include comparing an output signal of the audio signal electrical circuit to a reference, and calibrating the audio signal electrical circuit to correspond the output signal of the audio signal electrical circuit to the reference. Calibration of the audio signal electrical circuit enables more precise control of a cut-off frequency of a microphone signal when the output of the digital filter is input to the IDAC.

A tunable slope equalizer comprising a waveguide (e.g., rectangular waveguide) and posts (e.g., cylindrical posts) configured to move inside the internal cavity of the waveguide is presented. The degree of depth the posts may be inserted into the cavity of the waveguide may determine the orientation of the frequency response slope, e.g., positive or negative, and the maximum (or approximately maximum) insertion loss at minimum (or approximately minimum) or maximum (or approximately maximum) operating frequency, respectively. Being a mechanical device, the tunable slope equalizer may be fabricated at a relatively higher level of precision, leading to lower variances in performance over production.

A tunable slope equalizer comprising a waveguide (e.g., rectangular waveguide) and posts (e.g., cylindrical posts) configured to move inside the internal cavity of the waveguide is presented. The degree of depth the posts may be inserted into the cavity of the waveguide may determine the orientation of the frequency response slope, e.g., positive or negative, and the maximum (or approximately maximum) insertion loss at minimum (or approximately minimum) or maximum (or approximately maximum) operating frequency, respectively. Being a mechanical device, the tunable slope equalizer may be fabricated at a relatively higher level of precision, leading to lower variances in performance over production.

The present disclosure describes systems and devices for gain slope equalization in a radio frequency (RF) amplifier (200). The RF amplifier (200) may include an input stage (210) for receiving an RF signal. In conjunction with the input stage (210), the RF amplifier (200) may incorporate an amplification stage (215) to amplify the RF signal. Coupled with the amplification stage (215) may be a transformer (220) including a first winding to receive the amplified RF signal, a second winding providing an RF output signal, and a resonator including a third winding that is coupled to the first and second windings. The resonator may be coupled to a circuit network which may be tuned to affect the resonance frequency and the gain slope of the RF output signal.

The present disclosure describes systems and devices for gain slope equalization in a radio frequency (RF) amplifier. The RF amplifier may include an input stage for receiving an RF signal. In conjunction with the input stage, the RF amplifier may incorporate an amplification stage to amplify the RF signal. Coupled with the amplification stage may be a transformer including a first winding to receive the amplified RF signal, a second winding providing an RF output signal, and a resonator including a third winding that is coupled to the first and second windings. The resonator may be coupled to a circuit network which may be tuned to affect the resonance frequency and the gain slope of the RF output signal.