25W 40-500kHz power amplifier

The 5w power amplifier circuit is shown in Figure 8-6. It consists of a pre-stage, a push stage, a power stage and a power stage. }Li100 special functions
are composed of auxiliary circuits. The pre-stage is composed of VT] and other components. The pre-stage is mainly to increase the signal voltage and provide 75n input
pin I to achieve lj input impedance matching. Over-excitation protection constitutes the negative feedback p of the entire power amplifier circuit, which is composed of v-r'i, and is a radioactive
circuit 7. K, two is}: bias resistor, R4 is the lower bias resistor. R7~KlO constitute the emitter resistor, and R7 is used to generate DC
feedback to stabilize the DC operating point of the level. C 3 is the AC bypass capacitor . RS constitutes the negative feedback of this stage's series circuit, R 9,
...i. ) constitutes a successful negative feedback path. Rfi is the collector load resistance. RP], Ri. RZ is the input matching resistor. RP 1 also serves as
the input 8I乜;F state'1|J_potentiometer. (j 1 and C 5 are the inter-stage coupling capacitors o R5. C 2 is the high-frequency correction network o Rll, (1 4 is the current stage
: U source coupling circuit, over-excitation protection is connected to the base of VT1, by VI )1, VD2 constitute a full-wave rectification circuit , and the current
step is I (), ['12 filter oxime is added to the rectifier m carrier RP2. When the power stage input signal exceeds a certain value, the rectifier circuit Send death { Ji
's I also 』_i other { hinder v'I'7 咩 咩, and then make wr ] V,. r decrease, the output signal decreases, play the role of scratching excitation protection n iJ爿一书
l<l' 2 i¨l sticks past the micro-excitation protection point.