| 摘要 |
In a mixer of a converter, a bipolar transistor is connected between the base of a bipolar transistor and a positive power-supply node within a driving circuit, as a temperature characteristic compensating circuit. When the ambient temperature of the driving circuit rises, collector current of the transistor is increased due to the temperature characteristic of the transistor. This lowers the drain voltage of a high electron mobility transistor. However, collector current of the transistor within the temperature characteristic compensating circuit is also increased, increasing the voltage at a point, so that the increase in the collector current of the transistor is suppressed. This results in a stabilized drain voltage of the transistor. Therefore, the low noise down-converter can supply a stable voltage to a transistor performing frequency conversion, without any effect from the change in the ambient temperature.
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