L-Band SiGe HBT Differential Amplifiers with Multiple Bandpass or Bandstop Performance Using Stacked Parallel-Resonant Circuits

L-band SiGe HBT differential amplifiers with multiple bandpass or bandstop performance is presented. It incorporates stacked parallel-resonant circuits into the design of the output load of the differential amplifier to achieve multiple bandpass performance. On the other hand, the stacked parallel-resonant circuits are used between emitters of the differential transistor-pair to achieve multiple bandstop performance. With the use of the stacked parallel-resonant circuits, the quad-band bandpass amplifier demonstrates an averages gain of 9 dB at 0.54, 0.7, 1.08, and 1.39 GHz. On the other hand, the quad-band bandstop amplifier shows an averaged bandstop level of 6 dB at 0.34, 0.56, 0.73, and 1.07 GHz. The multiple bandpass or bandstop technologies are considered to be one of the candidates supporting the next generation multiband, multimode, adaptive or reconfigurable wireless radios.