Matching network circuit and radio-frequency power amplifier with odd harmonic rejection and even harmonic rejection and method of adjusting symmetry of differential signals
A matching network circuit for RF power amplifier circuit capable of odd harmonic rejection and even harmonic rejection in the differential mode and the common mode, respectively. The matching network circuit includes a differential mode filter with a differential resonant frequency and a passive component coupled to a virtual short circuit node at the differential mode filter, wherein a common mode filter with a common resonant frequency includes the differential mode filter and the passive component. As a result, two notch filters with different resonant frequencies are utilized for the common mode and the differential mode, respectively.
1. A matching network circuit, applied to a radio-frequency (RF) power
amplifier processing an RF input signal, comprising:
a first input node for receiving a first signal component of the RF input signal;
a second input node for receiving a second signal component of the RF input signal;
a first output node, wherein a first signal path of the first signal component of the RF input signal is formed between the first input node and the first output node;
a second output node, wherein a second signal path of the second signal component of the RF input signal is formed between the second input node and the second output node;
a symmetry node;
a first differential mode notch filter with a differential resonant frequency, coupled between the first signal path of the first signal component of the RF input signal and the symmetry node;
a second differential mode notch filter with the differential resonant frequency, coupled between the second signal path of the second signal component of the RF input signal and the symmetry node; and
a passive network circuit, comprising a first passive component, coupled to a ground and the symmetry node;
wherein a common mode notch filter with a common resonant frequency comprises the passive network circuit and one of the first and second differential mode notch filters.
2. The matching network circuit of claim 1 , wherein the passive component comprises a capacitor, and the common resonant frequency is higher than the differential resonant frequency.
3. The matching network circuit of claim 1 , wherein the passive component comprises an inductor, and the common resonant frequency is lower than the differential resonant frequency.
4. The matching network circuit of claim 1 , wherein the differential mode notch filter comprises an LC resonator.
5. The matching network circuit of claim 1 , wherein the symmetry node operates as a virtual short circuit if the matching network circuit operates in a differential mode, and matching network circuit operates as a virtual open circuit if the matching network circuit operates in a common mode.
6. The matching network of claim 1 , wherein the first and second signal components of the RF signal comprise a pair of differential signals.
7. The matching network of claim 1 , wherein the first and second input nodes are coupled to a power amplifier core stage circuit of the RF power amplifier, and the first and second output nodes are coupled to an output stage circuit of the RF power amplifier.
8. The matching network circuit of claim 1 , wherein the passive component comprises an LC resonator, and the common resonant frequency is decided according to an LC value of LC resonator.
9. The matching network circuit of claim 8 , wherein the LC resonator is used for common mode impedance tuning of an output impedance of the differential matching network.