| 摘要 |
PURPOSE:To compensate a variation in gain of each BPF by adjusting a resistance value of a resistor provided between a smoothing circuit and a differential amplifier after the forming of package to apply function trimming to the amplitude of a signal before it enters the differential amplifier. CONSTITUTION:A 16kHz BPF14 for 16kHz pilot signal, a 46kHz BPF5 for 46kHz pilot signal, a differential amplifier 10 receiving an output signal from the 16kHz BPF4 and the 46kHz BPF5 and comparing the amplitude of the signals, a fixed resistor 9, and a resistor 8 designed for function trimming are provided as a dynamic tracking circuit and the components are contained in one package as a hybrid IC. Before the package 11 is subjected completely to packaging by molding, the resistor 8 is trimmed by a laser or the like while supervising an output signal of the differential amplifier 18 with its input terminal 11A applied by a 16kHz pilot signal and a 46kHz pilot signal properly, thereby correcting the variation in the gain of both the BPFs. |
