A cellular radio architecture that includes a multiplexer coupled to an antenna structure and including multiple signal paths, where each signal path includes a bandpass filter that passes a different frequency band than the other bandpass filters and a circulator that provides signal isolation between the transmit signals and the receive signals. The architecture also includes a receiver module having a separate signal channel for each of the signal paths in the multiplexer, where each signal channel in the receiver module includes a receiver delta-sigma modulator that converts analog receive signals to a representative digital signal. The delta-sigma modulator includes an LC filter having a plurality of LC resonator circuits, a plurality of transconductance amplifiers and a plurality of integrator circuits, where a combination of one resonator circuit, transconductance amplifier and integrator circuit represents a two-order stage of the LC filter.

A DAC circuit includes: a PWM encoding circuit for converting a digital signal to first and second PWM signals, whereby a combination of the first and second PWM signals becomes a PWM encoded signal of at least 3 levels including a positive, a zero and a negative level, wherein the digital signal represents a number in a numerical range; and a demodulation circuit for generating the analog signal according to the first and second PWM signals. The first and second PWM signals have a minimum duty larger than 0 when the digital signal represents a middle number in the numerical range. The zero level of the combination of the first and second PWM signals has a duty which decreases as a difference between the number represented by the digital signal and the middle number increases.

An image sensor may include an array of image pixels coupled to analog-to-digital conversion circuitry formed from pinned photodiode charge transfer circuits. Majority charge carriers for the pinned photodiodes in the charge transfer circuits may be electrons for photodiode wells formed from n-type doped regions and may be holes for photodiode formed from p-type doped regions. Pinned photodiodes may be used for charge integration onto a capacitive circuit node. Pinned photodiodes may also be used for charge subtraction from a capacitive circuit node. Comparator circuitry may be used to determine digital values for the pixel output levels in accordance with single-slope conversion, successive-approximation-register conversion, cyclic conversion, and first or second order delta-sigma conversion techniques. The array of image pixels used for imaging may have a conversion mode wherein at least a portion of the pixel circuitry in the array are operated similar to the charge transfer circuits.

An image sensor may include an array of image pixels coupled to analog-to-digital conversion circuitry formed from pinned photodiode charge transfer circuits. Majority charge carriers for the pinned photodiodes in the charge transfer circuits may be electrons for photodiode wells formed from n-type doped regions and may be holes for photodiode formed from p-type doped regions. Pinned photodiodes may be used for charge integration onto a capacitive circuit node. Pinned photodiodes may also be used for charge subtraction from a capacitive circuit node. Comparator circuitry may be used to determine digital values for the pixel output levels in accordance with single-slope conversion, successive-approximation-register conversion, cyclic conversion, and first or second order delta-sigma conversion techniques. The array of image pixels used for imaging may have a conversion mode wherein at least a portion of the pixel circuitry in the array are operated similar to the charge transfer circuits.

An A/D converter includes an A/D conversion unit and an output unit. The A/D conversion unit includes a second A/D converter (successive approximation register A/D converter) and generates first digital data having a first number of bits and second digital data having a second number of bits, where the second number of bits is smaller than the first number of bits. The output unit provides first output information that is the first digital data and also provides second output information based on the second digital data. The output unit provides the second output information before providing the first output information.

A delta-sigma modulator is provided with: a loop filter 30; a quantizer 36 that generates quantized data on the basis of an output from the loop filter 30; an internal path 42 connected to the loop filter 30 or the quantizer 36; and a compensator 38 that provides, to the internal path 42, a compensation signal for compensating for distortion that occurs in a frequency component at a target frequency, the frequency component being among frequency components of a pulse train corresponding to the quantized data.

The dynamic range and power efficiency of a voice-activated system may be improved by dynamically adjusting the configuration of the voice-activated system's input path. In one embodiment, a first portion of audio may be received through an input path of the voice-activated system having a first configuration. A characteristic of the first portion of audio may be determined and the input path may be adjusted to a second configuration based on the determined characteristic. A second portion of audio may then be received through the input path having the second configuration, and speech analysis may be performed on the second portion of audio.

An integrator includes a first switch, a first capacitor, a second switch, a second capacitor, an amplifier, a third switch, a forth switch, a third capacitor, and a control circuit. The control circuit repeats a first phase and a second phase. In the first phase, the control circuit renders the first switch and the third switch to turn on and the second switch and the fourth switch to turn off. In the second phase, the control circuit renders the second switch and the fourth switch to turn on and the first switch and the third switch to turn off.

An analog-to-digital converter (ADC) includes a modulator, an integrator circuit, and first and second differentiator circuits. The modulator has a modulator input and a modulator output. The modulator input is configured to receive an analog signal, and the modulator is configured to generate digital data on the modulator output. The integrator circuit has an integrator circuit input and an integrator output. The integrator input is coupled to the modulator output. The first differentiator circuit is coupled to the integrator output, and the first differentiator circuit is configured to be clocked with a first clock. The second differentiator circuit is coupled to the integrator output, and the second differentiator circuit configured to be clocked with a second clock. The second clock is out of phase with respect to the first clock.

A sigma-delta ADC comprising: a first-input-terminal configured to receive a first-high-voltage-analogue-input-signal; a second-input-terminal configured to receive a second-high-voltage-analogue-input-signal; an output-terminal configured to provide an output-digital-signal, wherein the output-digital-signal is representative of the difference between the first-high-voltage-analogue-input-signal and the second-high-voltage-analogue-input-signal. The sigma-delta ADC also includes a feedback-current-block, which comprises: a first-feedback-transistor having a conduction channel; a second-feedback-transistor having a conduction channel; a first-feedback-switch; a second-feedback-switch; a first-feedback-current-source; and a second-feedback-current-source.