With the development of my country's cable TV, for TV modulator products, it plays a very important role in adjusting the signal. In fact, as a modulator, it is mainly an important link in a modulated DC amplifier circuit.
After the DC signal ui to be amplified passes through the PBI modulator, it becomes an AC signal U; after being amplified by the AC amplifier, it is finally converted into a DC output signal UO by the demodulator; the oscillator generates a switching signal U; it is used to control the modulator Sampling action. Since the signal amplification task is mainly completed by the AC amplifier, and the zero drift of the AC amplifier is negligible, the zero drift of the modulator and demodulator can also be made very small, so the modulated DC amplifier can be used to amplify weak DC signal,
PBI modulators generally come in three forms: mechanical modulators (mechanical choppers), transistor modulators, and FET modulators. According to the circuit form, it can be divided into parallel modulators and serial and parallel modulators. The latter has superior performance than the former, but the structure is complicated.
