Frequency synthesizer signal source ----- Frequency Signal Source

Frequency synthesizer signal source, Frequency Signal Source Keywords: frequency synthesizer signal source Frequency synthesizer signal source Frequency synthesis signal source is a high-performance signal generator because of its higher price makes general electronic enthusiasts unable to ask. This paper introduces a low-cost frequency synthesis signal source composed of a common element, a square wave signal of 0.7 Hz to 37 MHz, and has the same accuracy as the crystal. The circuit is shown in the drawings. ICL and TC9198 are a 4-digit programmable frequency divider. With four BCD DIP switches, its divide ratio can be arbitrary in 1-9999, with a maximum operating frequency of 30MHz, and actually reaches 37MHz. The IC2 is the phase-locked loop circuit 74HC4046AE, the function is the same as the CD4046, but the operating frequency is typically 20MHz. The power supply voltage is 5V. In this circuit, its lowest operating frequency is 70kHz, and then it does not work normally, the highest operating frequency is 37MHz, and the operating current is 40 mA. However, pay attention to do not use the model of 74HC4046N because its maximum frequency is difficult to exceed 30MHz. The IC3 74HC4060 and 6.4 MHz crystal constitute a 10kHz reference frequency source, 4060 divided ratio of 640, and other circuits form a 5-level decimal divider, extend through the divided minimum frequency to 0.7 Hz. Since the frequency range of the phase locking ring portion has a greater difficulty in capturing and locking frequencies, there is often a changed division value, and the voltage controlled oscillator cannot be changed at the highest frequency. The phenomenon. To this end, this circuit has added a stop-entered K. When the frequency is required, the switch K is first closed, so that the IC2's foot voltage is zero, when the voltage controlled oscillator is stopped, set the frequency, then open the switch K, the voltage controlled oscillator from the lowest end of the frequency, work It is reliable. At the same time, it can also be stopped when there is no need to output, to reduce the power consumption of IC2 74HC4046. However, it cannot be controlled by a stop-enriched control end of the 5 foot of 74HC4046. It is controlled to control the changing vibration, and the voltage controlled oscillator is still prone to the loop cannot be locked, and the frequency is the highest frequency. The TC9198 is set by the divided ratio, which can be used either a decimal dial switch, which is also available in the text. At this time, only the QL ~ Q16 is connected to the 4 ~ (19) foot of the TC9198.

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