| 摘要 |
<p>A radio frequency amplifier comprises a differential amplifier having a pair of differential first and second transistors (1,2) and a first and a second load resistor (4,5); an emitter grounded amplifier having a third transistor (6) and a third load resistor (7); and a reference voltage generator having a constant-current source formed by a fourth transistor (8) and a fourth load resistor (9). The emitter grounded amplifier receives a high frequency input signal and outputs a single signal output. One input node of the differential amplifier receives the output from the emitter grounded amplifier and the other input node receives a reference voltage from the reference voltage generator. The third and fourth transistors (6,8) form a current-mirror circuit. The DC bias voltages of the two input nodes of the differential amplifier are set to have the same value by an appropriate selection of the ratio between the currents (I6,I8) flowing in the third and fourth transistors (6,8) and also the ratio between the resistance values (R7,R9) of the third and fourth load resistors (7,9). This arrangement enables to divide a high frequency input signal into a single signal output and differential signal outputs. <IMAGE></p> |
