A NOVEL LOW-VOLTAGE CMOS VARIABLE GAIN AMPLIFIER WITH GAIN-INDEPENDENT INPUT IMPEDANCE MATCHING FOR DTV TUNING APPLICATIONS

摘要

This paper presents a novel low-voltage single stage CMOS RF Variable Gain Amplifier (RFVGA) designed in 130nm IBM CMOS process technology using current feed-back gain-independent impedance matching. The proposed RFVGA has a nearly constant gain over the 400MHz-lGHz frequency band. Also, it has a 70 dB gain variation (-10 dB to 30 dB) which is decibel-linear within this frequency band for a control voltage in the range of 0.41 V-0.81 V. The RFVGA demonstrates high linearity (THD ≈ -60 dB) and noise immunity (average Noise Figure ≤ 6dB). It has an input referred third-order intercept point (IIP3) of - 1.5dBm, and an input reflection coefficient (Sl1) under -8dB within the frequency band of interest. Also, it dissipates around 5mW using a 1.2 V power supply. Further, Monte Carlo simulations incorporating process, supply voltage and temperature variations (PVT variations) as well as mismatch between devices (based on width and length of devices) indicate that the design is quite robust. The proposed RFVGA is highly suitable for mobile digital television (DTV) tuner applications.