| 摘要 |
PURPOSE:To avoid the fluctuation of the modulation degree caused by the temperature by adding the bias circuit featuring the temperature characteristics to the amplitude modulator and then controlling the output change of the oscillator due to the temperature change via the increase and decrease of the bias current. CONSTITUTION:The output of oscillator 1' is applied to modulation diode 2', and the bias current applied to diode 2' is changed over by switch 3. This switching is carried out in correspondence to the value which is decided by the voltage and current connected to bias terminal 5' and 6' according to the modulation signal input 4. In this way, however, the modulation fluctuation due to the temperature is produced at the output emerging at output terminal 8' of circulator 7'. In this connection, the bias circuit consisting of current source 9 which does not change by the temperature and current source 10 which changes by the temperature is added previously to bias terminal 5'. As a result, the current flowing to diode 2' is set to difference current I1-I2 between two current sources 9 and 10 in order to keep the degree of modulation constant. |
