2results about How to "High frequency accuracy" patented technology

This application discloses a precision capacitance sensing system, comprising a modulation signal source, a sensitive probe, a differential transformer bridge, a signal amplification link, an analog multiplier, and a low-pass filter circuit, all connected in sequence. It also includes a demodulation reference signal source, the output of which is connected to the second input of the analog multiplier. The demodulation reference signal source is used to generate a multi-frequency combination demodulation reference signal, which is composed of a fundamental frequency component and at least two harmonic components superimposed. This invention also discloses a precision capacitance sensing method. By employing a specially designed demodulation reference signal, this application ensures that the system output remains constant within a continuously varying range of the demodulation phase difference, thereby achieving complete insensitivity to phase difference fluctuations and effectively overcoming the performance bottleneck that has long constrained high-precision capacitance sensing.

The application provides a method for automatically calibrating the frequency of an internal crystal oscillator, a controller chip, a household appliance and a storage medium, and the method comprises the following steps: obtaining a commercial alternating voltage signal; sampling the commercial alternating voltage signal at a current frequency of the internal crystal oscillator to obtain a sampling number within a preset sampling period; and obtaining a correction value of the current frequency according to a preset standard number corresponding to the sampling number and the current frequency, and adjusting the current frequency. The application can reduce the dependence on chip port resources while reducing the temperature influence when using the built-in oscillator of the chip.