Active 90-degree phase shifter with LC-type emitter degeneration and quadrature modulator IC using the same

• Main Authors: Horng, Tzyy-Sheng, Wu, Jian-Ming, Han, Fu-Yi, Lin, Jenshan
• Format: Patent
• Language: English
• Published: 09.12.2008

An active 90-degree phase shifter with LC-type emitter (source) degeneration is provided, which is practiced in an integrated circuit. The phase shifter comprises a first differential amplifier, having one first signal output end and comprising an inductor, a first transistor and a second transistor, wherein the inductor is connected to the emitters (sources) of the first and the second transistors; and a second differential amplifier, having one second signal output end and comprising a capacitor, a third transistor and a fourth transistor, wherein the capacitor is connected to the emitters (sources) of the third and the fourth transistors. Wherein the bases (gates) of the first and the fourth transistors are signal input ends, and the bases (gates) of the second and the third transistors are coupled together. Further, the phase shift between one signal input end and the first signal output end or the second signal output end is determined by the intrinsic resistors of the transistors, the inductor and the capacitor.