An ultra-low power sub-threshold g.sub.m stage is disclosed where transconductance is very stable with process, temperature, and voltage variations. This technique can be implemented in a differential amplifier with constant gain and a second order biquad filter with constant cut off frequency. The amplifier gain can achieve a small temperature coefficient of 48.6 ppm/° C. and exhibits small sigma of 75 mdB with process. The second order biquad can achieve temperature stability of 69 ppm/° C. and a voltage coefficient of only 49 ppm/mV.

A push-pull dynamic amplifier is operable in reset and amplification phases. The amplifier includes first NMOS and PMOS input transistors that are electrically coupled to a first input terminal and a first output terminal. Second NMOS and PMOS input transistors are electrically coupled to a second input terminal and a second output terminal. First and second reset switches are electrically coupled to the first and second output terminals, respectively. A power supply switch is electrically coupled to the first and the second PMOS transistors, and a ground switch is electrically coupled to the first and the second NMOS transistors. During the reset phase, the reset switches are closed and the power supply switch and the ground switch are opened. During the amplification phase, the reset switches are opened and the power supply switch and the ground switch are closed.

A switched-capacitor amplifier circuit includes multiple switched-capacitor networks, an amplifier, and multiple reset circuits. The switched-capacitor networks are configured to receive respective input voltages during a sampling phase, and generate sampled voltages. During an amplification phase, the amplifier is coupled with the switched-capacitor networks, and is configured to receive the sampled voltages. The amplifier is further configured to generate output voltages. During the sampling phase, the amplifier is coupled with the reset circuits, and is further configured to receive divided voltages such that the amplifier is reset. The reset circuits are configured to receive and provide a common-mode voltage and the output voltages to the amplifier. The divided voltages are generated based on the common-mode voltage and the output voltages. Each reset circuit includes at least one of a resistor and a capacitor.

A circuit arrangement comprises a first input node, a first output node, a sampling capacitor means and a first switching means being switchable between a first switching state and a second switching state. The first switching means is coupled to the sampling capacitor means, the first input node and the first output node in such a way that the sampling capacitor means is conductively connected to the first input node and disconnected from the first output node in the first switching state and the sampling capacitor means is disconnected from the first input node and conductively connected to the first output node in the second switching state. A first charge-storing element is coupled via a second switching means to the first input node in such a way that the charge-storing element is charged in the first switching state and discharged in the second switching state, thereby at least partly compensating current flow for charging the sampling capacitor means in the first switching state.

This application relates to driver circuitry (200) for receiving a digital input signal (D) and outputting, at first and second output nodes (203p, 203n), first and second analogue driving signals respectively for driving a transducer (101), e.g. loudspeaker, in a bridge-tied-load configuration. The driver circuitry may particularly be suitable for driving low-impedance transducers. The driver circuitry has first and second digital-to-analogue converters (201p, 201n) configured to receive the digital input signal and the outputs of the first and second digital-to-analogue converters are coupled to the first and second output nodes respectively. A differential-output amplifier circuit (202) has outputs connected to the first and second output nodes and is configured to regulate the outputs of the digital-to-analogue converters at output nodes to provide the analogue driving signals.

A device having a capacitive sampling structure that allows for removal of sampling noise can be implemented in a variety of applications. Noise cancellation can be achieved by storing on an auto-zero capacitor a scaled replica of kT/C noise by a mechanism of correlated sampling. In an example embodiment, a set of switches can be arranged such that, in switching, scaled thermal noise, generated in an acquisition phase in which a voltage signal is input to an input capacitor structure, is captured on an output capacitor structure and, in a conversion phase, the captured thermal noise is cancelled or compensated from an output of the output capacitor structure.

Signal quality is improved in a circuit for amplifying and sampling an analog signal. An input signal is input to one end of an input-side resistor. An operational amplifier amplifies the input signal, and outputs the input signal from an output terminal as an amplified signal. One end of a filter capacitor is connected to an input terminal of the operational amplifier. A predetermined frequency component of the input signal passes through the filter capacitor. A sampling capacitor imports the amplified signal during a predetermined sampling period, and holds the amplified signal during a predetermined hold period. A sampling switch connects the output terminal of the operational amplifier to one end of the sampling capacitor during the sampling period, and disconnects the output terminal of the operational amplifier from one end of the sampling capacitor during the hold period. A cutoff circuit disconnects the input-side resistor from one end of the filter capacitor during the sampling period, and connects the input-side resistor to one end of the filter capacitor during the hold period.

A device for buffering a reference signal comprises a regulator circuit configured to generate at least two replicas of the reference signal as regulated output signals. The device further comprises a receiving circuit configured to receive the regulated output signals in a switchable manner. In this context, the regulated output signals are configured to have different performance characteristics.

The present disclosure relates to a switchable power amplification structure including a first power amplifier (PA), a second PA, a front switching structure, and an end switching structure. The front switching structure is coupled to a radio frequency (RF) input port, and the end switching structure is coupled to an antenna port. Herein, the first PA and the second PA are parallel to each other, each of which is coupled between the front switching structure and the first end switching structure. The front switching structure is configured to selectively couple the first PA and the second PA to the RF input port, while the end switching structure is configured to selectively couple the first PA and the second PA to the first antenna port.

Magnetic field sensors and associated techniques use a Hall effect element in a current spinning arrangement in combination with a rippled reduction feedback network configured to reduce undesirable spectral components generated by the current spinning and other circuit elements.