Biasing circuit of power amplifier
A power amplifier and circuit technology, applied in the direction of improving amplifiers to reduce temperature/power supply voltage changes, etc., can solve problems such as low bias current of Q4 and cannot be turned on normally
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[0012] In order to solve the above technical problems, the present invention mainly relates to a constant voltage source circuit using a three-input operational amplifier for minimum output current protection.
[0013] When PM2, PM11 and RFI in the dotted box are omitted, figure 2 The circuit shown is a typical LDO regulated power supply. The bias current source and PM0, PM1, NM0, NM1, NM10, NM11, PM10 and PM11 form a typical two-stage operational amplifier. The PM12 driven by its output end generates VREF to supply power to the external circuit, and the resistor divider m*RFV and RFV generate a feedback voltage VFV and input signal V1 to jointly drive the input end of the operational amplifier. When the loop gain is high, the error between VFV and V1 is very small, and the output voltage Vref = (m+1)V1 is a constant voltage that does not change with temperature, such as image 3 As shown in A.
[0014] Since the turn-on voltage of the HBT decreases with the rise of the te...
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