Hycon Technology Corporation

Shui-Chu Lee

Po-Yin Chao

Hung-Wei Chen

Yu-Wei Chuang

The present invention discloses an AC impedance measurement circuit with a calibration function, which is characterized in that only one calibration impedance is needed, associated with a switch circuit. Based on the measurement results of the two calibration modes, an equivalent impedance of the switch circuit, circuit gain and phase offset can be calculated. Based on the above results, the equivalent impedance of the internal circuit is deducted from the measurement result of the measurement mode to accurately calculate an AC conductance and a phase of the AC conductance for impedance to be measured. In addition, by adjusting a phase difference between an input sine wave signal and a sampling clock signal, impedance of the same phase and impedance of the quadrature phase can be obtained, respectively, and the AC impedance and phase angle of the impedance to be measured can be calculated.

AC impedance measurement circuit with calibration function

Disclosed is a sensor with compensation circuit for compensating offset by use of a switching circuit. The sensor has two operation modes for generating two output voltages, respectively. Offset is compensated by adding the two output voltages, and magnitude of the offset is calculated by subtracting the two output voltages. A noise threshold is set for checking if the circuit is affected by interference. When the circuit is affected by interference, the adding result of the two output voltages will be larger than the noise threshold, the output data will be hold and not updated, then a reminding signal will be issued to show that the circuit is affected by interference, and the output data flickers on a display unit when the adding result of the two output voltages is larger than the noise threshold for showing the circuit is affected by interference.

Sensor with compensation circuit

Disclosed is a high accurate measurement circuit, and the feature is using bias switching circuit for compensating front end offset, and the back end offset of amplifier is also cancelled. In the real measurement environment, offset exists in the amplifier of the measurement circuit has, and non-ideal effects also exist in the interface between measurement terminal and the measurement circuit, such as leakage current of chip package pins or mismatch of the circuit. The above non-ideal effects belong to front end offset and cannot be compensated by the prior arts. The disclosed structure uses the bias switch circuit and uses different switching method in the two measurement timings. By subtracting the measurement results for the two measurement timings, the front end offset is compensated, and the back end offset of the amplifier is also cancelled.

Bias switch circuit for compensating frontend offset of high accuracy measurement circuit

Disclosed is an analog-to-digital converter with an adjustable operation frequency for noise reduction. The operation frequency of the analog-to-digital converter is adjustable, and if an input signal or a circuit is affected by a noise, the noise can be reduced by spreading the frequency distribution of the noise. A clock generator generates a clock signal for controlling the operation frequency of the analog-to-digital converter. Additionally, a clock controller receives a setting signal and a counting signal, controls the clock generator, and adjusts the frequency of the clock signal. In addition, a counter counts the number of periods of the clock signal, and generates the counting signal. Furthermore, a selecting signal makes the frequency of the clock signal gradually increase or decrease with time, thereby allowing change rate or change amount of the frequency of the clock signal to be adjustable.

Growing community of inventors

Taipei, Taiwan

Shui-Chu Lee