| 摘要 |
<p>An input signal (vi) supplied to an input terminal (10) is transmitted to a bias circuit (50) through a differentiating amplifier circuit (20) and current mirror circuit (40). In the rear stage of the bias circuit (50), first and second single ended push-pull (SEPP) circuit components (60,70) are connected in parallel between a power source (+V) and earth. The first SEPP circuit component (60) is formed of a pair of transistors (61, 62). The second SEPP circuit component (70) is formed of a pair of transistors (71, 72). An output signal from the junction (63) of the emitters of the transistors (61, 62) of the first SEPP circuit component (60) is negatively fed back to the differential amplifier through a resistor (26). The junction (73) of the emitters of the transistors (71, 72) of the second SEPP circuit component (70) is connected to the output terminal (80) of the amplifier device. A constant voltage (VB) is supplied from a constant voltage source (831 to the output terminal (80) of the amplifier device through resistors (81, 82). A series circuit formed of a constant-current source (100) and muting switch (102) is connected between a power source (+V) and a power supply circuit (30) for supplying power to the differential amplifier (20) and current mirror circuit (40). Where the muting switch (102) is opened, then the power supply circuit (30) is rendered nonconducting, preventing an input signal (vi) from being supplied to the bias circuit (50). As a result, the SEPP circuit components (60, 70) are unactuated to attenuate an output signal from the output terminal (80).</p> |
