| 摘要 |
PROBLEM TO BE SOLVED: To provide a negative power voltage automatic regulating circuit for a transmitting power amplifier in a simplified portable telephone which materializes stable transmission property in every product, stable battery life, and reduction of manhour at manufacture, by automatically regulating the negative power voltage value of the transmitting power amplifier so that the current consumption of the transmitting power consumption may come to a preset value. SOLUTION: A current detection.negative voltage controller 1 reads the voltage drop of the resistor R1 connected to a positive power source 4 with a microcomputer 2, and decides the bias value of an operational amplifier 13. The decision of this bias value is performed by dividing the negative voltage from a negative power generator 10 with resistors Ra-Rf, and turning on and turning off the switches Sa-Sf arranged in parallel individually. The negative power generator 10 comprises a clock generator 11 which generates clocks, a rectifying circuit which consists of an operational amplifier 12 to amplify this, diodes D1 and D2, and a capacitor C4, and an operational amplifier 13 which regulates the negative power voltage of the transmitting power amplifier of a power amplifier part 21. |
