Design of a 24–40 GHz balanced low noise amplifier using Lange couplers

A wide band （24–40 GHz） fully integrated balanced low noise amplifier （LNA） using Lange couplers was designed and fabricated with a 0.15 μm pseudomorphic HEMT （pHEMT） technology. A new method to design a low-loss and high-coupling Lange coupler for wide band application in microwave frequency was also presented. This Lange coupler has a minimum loss of 0.09 dB and a maximum loss of 0.2 dB over the bandwidth from 20 to 45 GHz. The measured results show that the realized four-stage balanced LNA using this Lange coupler exhibites a noise figure （NF） of less than 2.7 dB and the maximum gain of 30 dB; moreover, a noticeably improved reflection performance is achieved. The input VSWR and the output VSWR are respectively less than 1.45 and 1.35 dB across the 24–40 GHz frequency range.

An 8-18 GHz broadband high power amplifier

An 8-18 GHz broadband high power amphtier （HPA） with a hybrid integrated circuit （HIC） is designed and fabricated. This HPA is achieved with the use of a 4-fingered micro-strip Lange coupler in a GaAs MMIC process. In order to decrease electromagnetic interference, a multilayer AIN material with good heat dissipation is adopted as the carrier of the power amplifier. When the input power is 25 dBm, the saturated power of the continuous wave （CW） outputted by the power amplifier is more than 39 dBm within the frequency range of8-13 GHz, while it is more than 38.6 dBm within other frequency ranges. We obtain the peak power output, 39.4 dBm, at the frequency of I 1.9 GHz. In the whole frequency band, the power-added efficiency is more than 18%. When the input power is 18 dBm, the small signal gain is 15.7 ± 0.7 dB. The dimensions of the HPA are 25 × 15 × 1.5 mm^3.

Ka-band full-360° analog phase shifter with low insertion loss

A new reflection-type wideband 360° monolithic-microwave integrated-circuit （MMIC） analog phase shifter at the Ka-band is proposed. The phase shifter is designed based on the principle of vector synthesis. Three Lange couplers are employed in the phase shifter, which is fabricated by the standard 0.25μzm GaAs process. We use four 4 × 40μm GaAs HEMTs as the reflection loads. A microstrip line in parallel with the device is used as an inductance to counteract the parasitic capacitance of the device so that the reflection load performs like a pure resistance and the insertion loss can be decreased. In this phase shifter, a folded Lange coupler is utilized to reduce the size of the chip. The size of the proposed MMIC phase shifter is only 2.0 × 1.2 mm2. The measurement results show that the insertion loss is 5.0 4- 0.8 dB and a 360°continuously tunable range across 27-32 GHz is obtained with miniscule DC power consumption.