The frequency that analyses enlarge circuit is characteristic
[introduction] because magnify be put in reactance component C in circuit, the impedance that accordingly it presents to different frequency is different, enlarge circuit is so diploid to the enlarge of different frequency composition differ with phase shift.
One. Frequency character is summarized
(1) because magnify reactance component C exists in circuit, the impedance that accordingly it presents to different frequency is different, enlarge circuit is so diploid to the enlarge of different frequency composition differ with phase shift. The relation of enlarge multiple and frequency calls a frequency concern; Phasic call photograph frequency concern with the relation of frequency. Enlarge circuit job is in intermediate frequency zone time, the enlarge multiple of voltage does not change basically along with frequency, maintain one constant.
Low frequency area: Drop to magnify to intermediate frequency area when enlarge multiple diploid 0.707 times when, we call right now frequency Fl of floor level frequency. Amplifier job is in this zone time, the capacitive reactance that presents increases, because this magnifies multiple drops, add phase shift produces between output voltage and input voltage at the same time.
High frequency area: The enlarge multiple of high frequency zone time also drops. Because of amplifier the job is in high frequency zone time, the capacitive reactance decrescent of circuit, when frequency rises, make be added to enlarge circuit to input signal to reduce, make magnify multiple drops thereby.
(2) transmission bands is wide: Go up, the difference of floor level frequency, since transmission bands is wide. It is token enlarge circuit answer to the noise of the input signal of different frequency ability. Its definition is:
(3) end frequency: Affirmatory principle is: The cut-off with some capacitance definite place frequency, the constant number that is in loop with this capacitance shows undermentioned concern:
2. The frequency of multistage enlarge circuit is characteristic
(1) multistage enlarge circuit connects frequency wide
The frequency size of multistage enlarge circuit magnifies at only course the frequency of circuit is wide. Its upper limit frequency is less than the upper limit frequency of only course amplifier; Floor level frequency is big the floor level frequency with only course amplifier.
(2) go up, the computation of floor level frequency
Upper limit frequency satisfies relation: 
Floor level frequency satisfies a concern is: 