A novel S-band high linear passive mixer with an integrated driver amplifier

Abstract

This paper presents a high-linearity passive double-balanced mixer with an integrated driver amplifier using the 0.25um GaAs pseudomorphic high electron mobility transistor (pHEMT) process. We adopt a novel diode structure, which improves the linearity of the mixer by increasing the mixer’s intermodulation rejection ratio. An improved Marchand balun is designed to reduce the chip area and simultaneously have a low amplitude and phase imbalance. As a result of the integrated driver amplifier, this mixer can achieve frequency conversion at a lower local oscillator (LO) power. The proposed mixer’s radio frequency (RF) bandwidth is 1.7-4.3GHz, and the intermediate frequency (IF) bandwidth is DC-1.2GHz. The experimental results demonstrate that this mixer has an input 1dB compression point (IP_1dB) range of 20-23dBm and a third-order input intercept point (IIP3) range of 25-35dBm at 0dBm LO drive. This mixer’s conversion loss within the operating frequency band is 8.5-10dB. The LO to IF isolation is over 30dB, and the RF to IF isolation can reach 50dB. The total chip area is 1.4×3mm².