Design of high-frequency low-power FM transmitter

Since the modulation is simple AM transmitter, modulating the share of narrow-band, and corresponding amplitude to accept simple equipment, so widely used in broadcast AM transmitter fired.
AM transmitter key indicators are:
Operating frequency range: AM system generally used in short-wave radio communications, the operating frequency range 300KHZ ~ 30MHZ.
Transmit Power: transmit power generally refers to delivery to the antenna on the transmitter power. Only the day line the length of the oscillation frequency and the transmitter is comparable to the wavelength λ, the antenna can be effectively transmitted out to the carrier. Relationship between wavelength and frequency is: λ = c / f. The formula, c for the electromagnetic wave velocity, c = 3 × 108m / s.
Amplitude Modulation: Amplitude Modulation ma is the amplitude signal V control voltage V0 carrier amplitude coefficient, ma range from 0 to 1.
Non-linear distortion: modulation characteristics of the modulator can not follow the linear modulation voltage changes caused by the modulated wave AM transmitters, including distortion of the non-linear clock, generally require less than 10%.
Linear distortion: to maintain constant amplitude modulation voltage, changing the modulation frequency range of properties due to changes in tone as linear distortion.
Acoustic noise level shower level is not modulated signal, generated by the noise and signal transfer rate of the maximum transfer rate when the ratio of radio transmitters in the noise level is less than 0.1% required general communication equipment early sound level required less than 1%.
Overall efficiency: launcher, the total power consumption of PA and its total power P'c of
Than the overall efficiency of the system known as the launch
Circuit Type Selection:
AM transmitter is the main vibration, buffer, high-frequency voltage amplification
Device, amplitude modulators, high-frequency power amplifier circuit.

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