| 摘要 |
A power supply for an RF PA stage 2 includes a switch-mode stage 10 and a correction stage 16 which both receive an input signal 32. The outputs of the switch-mode stage 10 and the correction stage 16 are combined in a combiner circuit 30, in which current from the switch mode stage 10 passes through an inductor 14. According to the invention, a shunt impedance 42 is connected to the output of the switching stage. The shunt impedance may be connected to either terminal of the combining inductor. The shunt impedance 42 substantially reduces high frequency components of the ripple current (figures 2 & 4). The shunt circuit 42 may be switched in and out of circuit to reduce noise when required. |
