Abstract in simplified Chinese:本发明乃有关于数码对模拟转换器,且特别是但非独一地和换式电容器数码对模拟转换器(DACs)相关。本发明提供一耦合在一运算放大器之输入与输出之间的回馈电容器;一充电电容器和一切换设备,该切换设备配置成在一充电期间依数码信号而定将该充电电容器的第一端耦合至一第一参考电压或一第二参考电压,该切换设备进一步更被配置成在该充电期间将充电电容器之第二端耦合至与合至该充电电容器第一端之参考电压成反相的第二参考电压或第一参考电压,此切换设备更被配置成于一稳定期间将该充电电容器耦合至该回馈电容器。
Abstract:
This application relates to circuitry for processing sense signals generated by MEMS capacitive transducers for compensating for distortion in such sense signals. The circuitry has a signal path between an input (204) for receiving the sense signal and an output (205) for outputting an output signal based on said sense signal. Compensation circuitry (206, 207) is configured to monitor the signal at a first point along the signal path and generate a correction signal (S corr ); and modify the signal at at least a second point along said signal path based on said correction signal. The correction signal is generated as a function of the value of the signal at the first point along the signal path so as to introduce compensation components into the output signal that compensate for distortion components in the sense signal. The first point in the signal path may be before or after the second point in the signal path. The monitoring may be performed in an analogue or a digital part of the signal path and in either case the modification may be applied in an analogue or a digital part of the signal path.
Abstract:
This application describes apparatus and method for DC offset compensation. An amplifier (102) receives an input signal (AIN) and provides an amplified output signal (SOUT) and a feedback path provides DC offset compensation. The feedback path comprises at least one voltage controlled oscillator (VCO) (108) and a counter (109). The VCO provides, over time, a first VCO output signal based on said amplified output signal and a second VCO output signal based on a reference signal (VREF). The counter generates first pulse counts based upon the first VCO output signal and second pulse counts based upon the second VCO output signal and provides a compensation signal based on a comparison of the first and second pulse counts. One voltage controlled oscillator (108) may sequentially receive a signal based on said amplifier output signal and the reference signal from a multiplexer (110) so as to sequentially produce the first and second VCO output signals.
Abstract:
This invention relates to methods and apparatus for control of DC-DC converters, especially in valley current mode. The DC-DC converter (100) is operable so that a low side supply switch (20) may be turned off, before the high side supply switch (10) is turned on. During the period when both switches are off the current loop control (501) remains active and the change in inductor (L) current is emulated. One embodiment uses a current sensor (800) for lossless current sensing and emulates the change in inductor current by holding the value of the output of the current sensor (ISNS) at the time that the low side switch turns off and adding an emulated ramp signal (VISLP) until the inductor current reaches zero. Embodiment employing a pulse-skip mode of operation based on a minimum conduction time are also disclosed. The invention enables a seamless transition from Continuous Conduction Mode the Discontinuous Conduction Mode and Pulse Skipping and provide converters that are efficient at low current loads.
Abstract:
This invention relates to apparatus and method for providing current limiting in a DC- DC converter and especially to methods and apparatus suitable for a start-up mode of operation. The invention monitors the inductor (L) current when the high side supply switch (10) is on against a peak current limit threshold (5001). If the inductor current reaches the peak current limit threshold the high side switch is turned off. The inductor current when the low side switch is off is monitored against a valley current threshold (5002). As long as the inductor current is above the valley current threshold turn on of the low side switch is inhibited. In this way current limiting is provided and the problems of stair-stepping are avoided. Embodiments employing lossless current sensing are described. The invention may be implemented in a start-up mode of operation wherein the converter is controlled purely by the peak current limit and valley current threshold which are increased over time.
Abstract:
A noise cancellation signal is generated based on detected ambient noise, such that the noise cancellation signal and a wanted sound signal can be applied to a speaker. Gain control is applied to the wanted sound signal based on a comparison between the detected ambient noise level and the wanted sound signal level, for example such that the level of the wanted sound signal after the gain has been applied exceeds the level of a detected ambient noise signal by a certain threshold. Steps may also be taken such that the total level of the wanted sound signal after the gain has been applied and of the detected ambient noise signal do not exceed a second threshold, to avoid saturating the speaker to which they are applied.
Abstract:
A regulator circuit (400) comprises an input for receiving an input voltage; an output stage, configured to switch between said input voltage and a reference voltage to generate an output voltage, in dependence on a modulated signal; a controller (600), configured to receive an error signal (V ERROR ) on a control input and to provide said modulated signal to said output stage;an error amplifier (411), for providing said error signal to said controller (600) in dependence on said output voltage; and presetting circuitry (418), configured to estimate said error signal in dependence on at least said input voltage, and for presetting said control input with said estimated error signal.
Abstract:
The present invention provides a real-time clock circuit (54), comprising: an oscillator (122); and a counter (124), coupled to an output of the oscillator (122), for generating a real-time clock value. In a first mode the oscillator (122) is configured to generate oscillations and the counter (124) is configured to increment the real-time clock value based on the oscillations. In a second mode the oscillator (122) is stopped, and the counter (124) is configured to retain the real-time clock value at a frozen value.
Abstract:
This invention relates to methods and apparatus for control of DC-DC converters. The DC-DC converter (100) is operable so that the low side supply switch (20) may be inhibited from turning on in a cycle following the high side supply switch (10) turning off. Turn on of the low side switch is inhibited if the time between turn off of the high side switch (10) and the inductor (L) current reaching zero is less than a predetermined duration. Inhibiting the low side switch from turning on can prevent the inductor current from going negative, which would reduce the efficiency of the converter. When turn on of the low side switch is inhibited the inductor current flows through a parallel path, such as a parasitic body diode associated with the low side switch, which allows current flow in one direction only.