一种具有深度二次谐波抑制的微波振荡器

微波振荡器作为通信系统中的关键器件,已经被广泛地研究和设计。因此,设计具有优秀性能的微波振荡器是至关重要的。提出一种具有深度二次谐波抑制性能的新型微波负阻型振荡器。该设计的新颖性在于利用一个装配于双极结型晶体管射极的并联结构(由一段短微带线和电容并联组成)来实现二次谐波抑制。该结构作为振荡器基波信号的反馈元件,同时作为二次谐波处的带阻结构。因为二次谐波没有反馈回路(接地),所以能被极大地抑制。更重要的是在振荡器的输出端无额外的滤波器来抑制二次谐波,这使得电路尺寸得以减小。给出了一个振荡器设计实例,并给出其测试结果来论证理论的正确性。测试结果表明相较于传统振荡器的二次谐波抑制度有25 dB 的提高。

A Microwave Oscillator with High Second-Harmonic Suppression

As a key component in communication systems, microwave oscillators have been widely studied and designed. A novel microwave negative-resistance oscillator with high second-harmonic suppression is proposed in this paper.The novelty of this design lies in a combination structure (a short microstrip line and a lumped capacitor in parallel), which is incorporated at the emitter of the transistor (Bipolar Junction Transistor). It not only functions as a feedback element for the fundamental signal of the oscillator but also operates as a bandstop structure for the second harmonic. As a result, there is no return path (ground) for the second harmonic, which is accordingly suppressed to a great extent. Moreover, no additional filter is used to suppress the second harmonic, resulting in a reduced circuit size. A design example is presented in this paper. Its measured results are given to verify the theoretical prediction. There is about 25 dB improvement of the secondharmonic suppression, as compared with the conventional oscillator.