| 摘要 |
PURPOSE:To prevent at DC drift generated by the demodulator of a TDMA receiver from being amplified by a base band amplifier as it is by generating the reference voltage of the base band amplifier by utilizing the output of a monostable multivibrator on the same chip. CONSTITUTION:A modulated IF signal is amplified by an IF amplifier 1 and inputted to the monostable multivibrator 2. The monostable multivibrator 2 generates pulses whose number corresponds to the input frequency and the signal is passed through a low-pass filter 4, amplified by the base band amplifier 5, and inputted to a comparator 6. At this time, the DC drift generated by the monostable multivibrator 3 owing to temperature variation is canceled by the base band amplifier 5 with a DC drift generated by the monostable multivibrator 3 of a reference voltage circuit 3' similarly, so its influence never appears at the output of the base band amplifier 5. |
