| 摘要 |
According to the general concept disclosed herein a circuit for adaptive matching of a load impedance (z load) to a predetermined load-line impedance of a load-line connected to a power amplifier (300) output comprises a fixed matching network (201) between the power transistor and an adaptive matching network (101), whereby the fixed matching network acts as an impedance inverter which results in a relatively low insertion loss at high power. Results indicate that the impedance-inverting network can be used over more than a factor of 10 in impedance variation. Further, the usage of the fixed matching network, close to the power transistor, allows for the implementation of transmission zeros and/or for a well defined load impedance at a predetermined harmonic frequency, independent of the (variable) load impedance at the fundamental frequency. |
