A 0.5 to 6 GHz wideband cascode LNA with enhanced linearity by employing resistive shunt‐shuntfeedback and derivative superposition

Abstract

A wideband bipolar low‐noise amplifier (LNA) with enhanced linearity operating in 0.5 to 6 GHz frequency range is proposed in this letter. The LNA design is based on a cascode amplifier with an emitter degeneration RC parallel network and a resistive shunt‐shunt feedback which can improve linearity. The cascode topology in conjunction with the preceding series inductor L is utilized to achieve good wideband input impedance matching, while the wideband output impedance matching is realized by using an emitter follower as a buffer. And the third‐order input intercept point (IIP3) has been improved due to the derivative superposition technique. The wideband LNA presented in this letter was designed and implemented in a JAZZ 0.18 μm SiGe BiCMOS process. The measured results show that from 500 MHz to 6 GHz, the power gain (S21) is 16.5 to 17.1 dB, the noise factor (NF) is 2.7 to 3.3 dB, the current consumption without buffer stage is 12.4 mA at a 3.3 V supply voltage, and the IIP3 is −0.834 dBm at 2 GHz. The chip size is 1.06 × 0.64 mm2.

A 6–18 GHz high dB‐linear attenuator based on variable gain amplifier for ultra‐wideband phased array systems

“…And current steering part based on the emitter resistor-capacitor (RC) negative feedback and transistor segmentation technique is absorbed in this design for the bandwidth and gain flatness. 4 The dB-linear compensation unit is designed to improve dB-linearity in the 20 dB variable gain range. The current steering and dB-linear compensation are analyzed and discussed below.…”

“…3 Furthermore, the characteristics of gain control linearity, bandwidth, and attenuation precision are very important if the VGA is used for ultrawideband phased array systems. 4 For these performance characteristics of VGA, linear-in-dB gain control characteristics can provide continuous gain tuning, which has a great influence on the bandwidth and the attenuation precision. 5 In recent years, many efforts have been made in the design optimization of VGAs.…”