A digital filter and a method for filtering a pulse density modulation (PDM) signal are presented. The digital filter has a first filter circuit to receive an input signal with input values at successive time steps to provide a filtered input signal with filtered values at successive time steps. The digital filter does not require sample-rate or data format conversions. Also, the digital filter is area and power efficient when implemented in hardware. Optionally, the digital filter has a sigma-delta modulator including the quantiser, the sigma-delta modulator being used to receive the filtered input signal and to process the filtered input signal before and/or after being quantised by the quantiser. This digital filter does not require sample-rate or data format conversions. This digital filter is area and power efficient when implemented in hardware.

A digital microphone compresses a large voltage swing signal from a MEMS capacitor to a signal suitable for processing by integrated circuitry. The compression may be performed in an analog domain by selectively coupling adjustment capacitors in parallel to the MEMS capacitor. The digital microphone may decompress the signal in the digital domain using a decompression technique substantially an inverse of the compression performed in the analog domain.

A delta-sigma modulator may include a loop filter having a loop filter input configured to receive an input signal and generate an intermediate signal responsive to the input signal and a near-zero asymmetric quantizer configured to quantize the intermediate signal into a quantized output signal which is fed back as an input to the loop filter such that the quantized output signal has a plurality of quantization levels, wherein the plurality of quantization levels are asymmetric to zero.

A delta-sigma modulator generates a bit stream signal from an analog signal by operating according to a modulation period including a sampling period and a filtering period and includes a digital-to-analog converter (DAC) configured to generate a charge signal according to one of a first reference voltage and a second reference voltage according to the bit stream signal during the sampling period and to output a signal generated according to the charge signal and the other of the first reference voltage and the second reference voltage; a loop filter configured to charge a sampling signal corresponding to the analog signal during the sampling period and to filter an output from the DAC and a signal generated according to the sampling signal during the filtering period; and a quantizer configured to generate the bit stream signal according to an output from the loop filter in the modulation period.

Circuits and methods for converting digital input signals into the analog domain are described. Such circuits may perform the conversion in a segmented fashion. For example, a circuit may include a most significant bit (MSB) path and a least significant bit (LSB) path. The MSB path may include a first delta-sigma modulator having first and second outputs and a first digital-to-analog converter coupled to the first output of the first delta-sigma modulator. The LSB path comprises a second delta-sigma modulator comprising a loop filter and a quantizer. The quantizer may have an input coupled to the loop filter and to the digital filter. The LSB path may further include a second digital-to-analog converter coupled to an output of the quantizer. The circuit may further include a digital filter and/or a gain stage interposed between the MSB path and the LSB path.

A method comprising activating an internal switch within a packaged electronic device to connect to a reference ground of an internal voltage source to a first input of an analog front end, receiving an external ground potential voltage at a first package pin of the packaged electronic device, generating a zero detector output signal for the packaged electronic device at a second package pin, activating the internal switch to connect the first input of the analog front end to the internal voltage source, receiving a second voltage level at the first package pin that generates a second output signal that matches the zero detector output signal, and receiving trim instructions to trim an internal voltage generated by the internal voltage source to a voltage level that is closer to a target voltage level.

An oscillator includes a quartz crystal resonator and a circuit device, and the circuit device includes an oscillation circuit and a PLL circuit. The PLL circuit includes a phase comparison circuit that performs a phase comparison between the reference clock signal and a feedback clock signal, a control voltage generation circuit that generates a control voltage based on a result of the phase comparison, and a voltage control oscillation circuit that generates a clock signal having a frequency corresponding to the control voltage, and a frequency division circuit that divides a frequency of the clock signal and outputs the feedback clock signal. An oscillation frequency of the quartz crystal resonator is higher than or equal to 200 MHz, and a phase comparison frequency of the phase comparison circuit is higher than or equal to 200 MHz.

A circuit includes a programmable gain amplifier (PGA) having a PGA output. The circuit further includes a delta-sigma modulator having an input coupled to the PGA output. The circuit also includes a digital filter and a dynamic range enhancer (DRE) circuit. The digital filter is coupled to the delta-sigma modulator output. The DRE circuit is coupled to the delta-sigma modulator output and to the PGA. The DRE circuit is configured to monitor a signal level of the delta-sigma modulator output. Responsive to the signal level being less than a DRE threshold, the DRE circuit is configured to program the PGA for a gain level greater than unity gain and to cause the digital filter to implement an attenuation of a same magnitude as the gain level to be programmed into the PGA.

An electric control device includes a first delta sigma modulator having a clock input connection, a second delta sigma modulator having a clock input connection, and an evaluation unit. The evaluation unit includes a first clock output connection which is connected to the clock input connection of the first delta sigma modulator by a first electrical cable, and a second clock output connection which is connected to the clock input connection of the second delta sigma modulator by a second electrical cable. The evaluation unit is designed to generate a clock signal (CLK1) at the first clock output connection (7) in phase opposition to a clock signal (CLK2) at the second clock output connection (9).

A correction method and a correction circuit for a sigma-delta modulator (SDM) are provided. The SDM includes a loop filter, a quantizer, and a digital-to-analog converter (DAC). The correction method includes the following steps: controlling the DAC not to receive the output of the quantizer; controlling the SDM to stop receiving signals; inputting a test signal to the DAC; converting the output of the loop filter to a digital signal; comparing the digital signal with a preset value; and adjusting the loop filter according to the result of comparing the digital signal and the preset value.