The invention discloses an anti-interference device applied to POS terminal wired audio communication The anti-interference device is arranged at the receiving end of a POS terminal The anti-interference device comprises an audio signal input end, a DC isolation circuit, a high-frequency filter circuit, a Schmitt trigger unit and a microcontroller unit Dual anti-interference design is performed at the receiving end of the POS terminal so that communication stability can be greatly enhanced; filtering, amplification and anti-interference processing is performed on an audio signal transmitted by a mobile phone end via a hardware circuit with a Schmidt function so that interference pulse with lower interference amplitude can be effectively filtered, then filtering processing is performed on interference pulse with higher interference amplitude appearing in the audio signal via signal processing of the microcontroller unit and thus an effective signal is reduced; therefore, the anti-interference function of the POS terminal is realized, influence of interference of the audio port of the mobile phone end on signal receiving of the POS terminal is reduced, and thus work of the POS terminal is enabled to be more stable and reliable

Anti-interference device applied to POS terminal wired audio communication

The invention discloses an oscillator and an electronic terminal. The oscillator comprises a ramp signal generating module, a window voltage setting module, a comparing module and a logic control module. According to the oscillator, the ramp signal generating module receives a first square signal generated by the logic control module, generates a ramp signal according to the first square signal, sends the ramp signal to the comparing module, and provides synchronizing current for the window voltage setting module, wherein the ramp signal and the first square signal are the same in frequency. The window voltage setting module sets a high threshold voltage and a low threshold voltage and outputs the high threshold voltage and the low threshold voltage to the comparing module. The comparing module compares the generated ramp signal with the high threshold voltage and the low threshold voltage, generates a second square signal with a first duty ratio and outputs the second square signal to the logic control module, wherein the second square signal and the ramp signal are consistent in frequency. The logic control module shapes the second square signal into the first square signal, outputs the first square signal, and feeds the first square signal back to the ramp signal generating module to control the frequency of the ramp signal, so that the frequency of the ramp signal and the frequency of the first square signal are kept consistent, and the stability of the output frequency of the oscillator is improved.

Oscillator and electronic terminal

A system for tuning an oscillator frequency. The system includes a trimmed calibration circuit comprising a comparator and trimmed delay element and calibration logic. The calibration logic is configured to receive an output of the comparator and control an on time and an off time of an oscillator based on the output of the comparator.

Systems and methods for tuning an oscillator frequency

The invention provides a ring first in first out buffer (FIFO) and a data transmission interface, a system, a method, a synchronization circuit synchronizes a comparison result of a write pointer anda read pointer by a specific number of clock signal cycles, It can realize the data transmission between different clock domains, and can increase the Jitter margin of the ring FIFO buffer and improvethe anti-noise ability of the ring FIFO buffer when the FIFO depth is the same Further, the synchronization circuit synchronizes the comparison result of the write pointer and the read pointer by (M/2 - 0 5) clock signal cycles, so that the ring FIFO buffer has a Jitter margin of (M/2-1 5) clock signal cycles when it is read empty and full, where M is the depth of the FIFO When the FIFO depthis 4, the invention is suitable for the application of DDR, and can obtain Jitter margin of 05 clock signal cycles both empty and full under minimum hardware resource consumption

Ring FIFO buffer and data transmission interface, system and method

In some embodiments, the present disclosure relates to a frequency generator having a resistor network and a capacitor network The capacitor network has a plurality of capacitors connected in parallel with one another A comparator is configured to output an oscillating voltage signal An input of the comparator is connected to the output of the resistor network and the output of the capacitor network A frequency testing circuit is configured to calculate a frequency of the oscillating voltage signal and determine whether the frequency is within a range of an expected frequency The frequency testing circuit may also be configured to selectively connect a first plate of the plurality of capacitors to a non-varying voltage or to the input of the capacitor network to adjust a frequency of the oscillating voltage signal

Robust trimming scheme for low power RC oscillator compatible with high temperature operation

The invention discloses a relaxation oscillator with the frequency jittering function. The relaxation oscillator mainly solves the problem that an existing switching power source is relatively concentrated in energy of electromagnetic interference and has great influences on a power source system. The relaxation oscillator comprises an RC charge-discharge network (201), a first comparator (202), a second comparator (203), an RS trigger (204) and a frequency jittering control module (205). After a sawtooth voltage generated by the RC charge-discharge network (201) is compared with two threshold voltages through the two comparators, the sawtooth voltage is output to the RS trigger (204) to generate square signals with variable frequencies, charging or discharging of the RC charge-discharge network (201) is fed back and controlled by the square signals, the square signals simultaneously serve as clock signals to periodically change the charge-discharge capacitance in the RC charge-discharge network (201) through the frequency jittering control module (205), the frequencies of the output square signals are changed in a linear mode, and therefore the energy of the electromagnetic interference is dispersed. According to the relaxation oscillator, influences of the electromagnetic interference in a switching power source can be effectively reduced, and the relaxation oscillator can be used for management class chips of the switching power source.

Shao Lili

Papers

Relaxation oscillator with frequency jittering function