A system includes a Zero IF transmitter having a mixer and a programmable gain stage. The Zero IF transmitter also includes an intermediate stage between the mixer and the programmable gain stage, wherein the intermediate stage is configured to decouple the mixer and the programmable gain stage.

A system includes a Zero IF transmitter having a mixer and a programmable gain stage. The Zero IF transmitter also includes an intermediate stage between the mixer and the programmable gain stage, wherein the intermediate stage is configured to decouple the mixer and the programmable gain stage.

An example apparatus includes: an on-off keying (OOK) modulator including: a first transistor including a first control terminal; a second transistor including a first current terminal, a second current terminal, and a second control terminal, the first current terminal coupled to the first control terminal; a third transistor including a third current terminal, a fourth current terminal, and a third control terminal, the third current terminal coupled to the first control terminal; a fourth transistor including a fifth current terminal, the fifth current terminal coupled to the second current terminal; and a fifth transistor including a sixth current terminal, the sixth current terminal coupled to the fourth current terminal.

An example apparatus includes: an on-off keying (OOK) modulator including: a first transistor including a first control terminal; a second transistor including a first current terminal, a second current terminal, and a second control terminal, the first current terminal coupled to the first control terminal; a third transistor including a third current terminal, a fourth current terminal, and a third control terminal, the third current terminal coupled to the first control terminal; a fourth transistor including a fifth current terminal, the fifth current terminal coupled to the second current terminal; and a fifth transistor including a sixth current terminal, the sixth current terminal coupled to the fourth current terminal.

A digital predistorter comprising a first predistorter for generating out-of-band and inter-band distortion components for compensating for the static nonlinearity of a nonlinear element, and a second predistorter cascaded with the first predistorter, the second predistorter compensating for the in-band distortion of the nonlinear device wherein the cascade of the first predistorter and the second predistorter compensate for in-band, out-of-band and inter-band distortions when the cascade of the first, the second predistorter and the nonlinear element are driven with multiband signals.

In one example, a communications circuit processes an amplitude modulated signal by using a first circuit having signal paths to process an amplitude modulated signal as represented by an in-phase component and by a quadrature component, and by using a second circuit to discern random noise pulses from the quadrature component of the amplitude modulated signal. In response, the second circuit generates an estimate of overall noise representing the random noise pulses in the amplitude modulated signal. In the above and more specific examples, the random noise pulses may appear as pulses which overlap with, in terms of time and bandwidth of frequency spectrum, information of the amplitude modulated signal, and the first and second circuits may be part of an RF radio receiving the amplitude modulated signal from an antenna.

In one example, a communications circuit processes an amplitude modulated signal by using a first circuit having signal paths to process an amplitude modulated signal as represented by an in-phase component and by a quadrature component, and by using a second circuit to discern random noise pulses from the quadrature component of the amplitude modulated signal. In response, the second circuit generates an estimate of overall noise representing the random noise pulses in the amplitude modulated signal. In the above and more specific examples, the random noise pulses may appear as pulses which overlap with, in terms of time and bandwidth of frequency spectrum, information of the amplitude modulated signal, and the first and second circuits may be part of an RF radio receiving the amplitude modulated signal from an antenna.

Techniques are described for using valley detection for supply voltage modulation in power amplifier circuits. Embodiments operate in context of a power amplifier circuit configured to be driven by a supply voltage generated by a supply modulator and to receive an amplitude-modulated (AM) signal at its input. The output of the power amplifier circuit can be fed to a valley detector that can detect a valley level corresponding to the bottom of the envelope of the AM signal. The detected valley level can be fed back to the supply modulator and compared to a constant reference. In response to the comparison, the supply modulator can vary the supply voltage to the power amplifier circuit in a manner that effectively tracking the envelope of the power amplifier circuit's output signal, thereby effectively seeking a flat valley for the output signal's envelope.

In one example, a communications circuit processes an amplitude modulated signal by using a first circuit having signal paths to process an amplitude modulated signal as represented by an in-phase component and by a quadrature component, and by using a second circuit to discern random noise pulses from the quadrature component of the amplitude modulated signal. In response, the second circuit generates an estimate of overall noise representing the random noise pulses in the amplitude modulated signal. In the above and more specific examples, the random noise pulses may appear as pulses which overlap with, in terms of time and bandwidth of frequency spectrum, information of the amplitude modulated signal, and the first and second circuits may be part of an RF radio receiving the amplitude modulated signal from an antenna.

In one example, a communications circuit processes an amplitude modulated signal by using a first circuit having signal paths to process an amplitude modulated signal as represented by an in-phase component and by a quadrature component, and by using a second circuit to discern random noise pulses from the quadrature component of the amplitude modulated signal. In response, the second circuit generates an estimate of overall noise representing the random noise pulses in the amplitude modulated signal. In the above and more specific examples, the random noise pulses may appear as pulses which overlap with, in terms of time and bandwidth of frequency spectrum, information of the amplitude modulated signal, and the first and second circuits may be part of an RF radio receiving the amplitude modulated signal from an antenna.