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Sistemi Elettronici Integrati – B17. High-dynamic-range VGA with temperature compensation and linear-in-dB gain control. Francesco Carrara and Giuseppe Palmisano Radio Frequency Advanced Design Center (RF-ADC). Università di Catania Facoltà di Ingegneria DIEES Catania - ITALY.
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Sistemi Elettronici Integrati – B17 High-dynamic-range VGA with temperature compensation and linear-in-dB gain control Francesco Carrara and Giuseppe Palmisano Radio Frequency Advanced Design Center (RF-ADC) Università di Catania Facoltà di Ingegneria DIEES Catania - ITALY STMicroelectronics Catania site
INTRODUCTIONRequirements for WCDMA TX VGAs • Wide dynamic range (as high as 74 dB for Class 3 user equipment) • Temperature compensation for accurate control over such a wide dynamic range • Decibel-linear gain characteristic to minimize the resolution of the DAC driving the control terminal • High linearityto comply with ACLR specification TX VGAs are crucial in optimizing the channel capacity of code-division systems like WCDMA Main requirements are:
CIRCUIT DESIGNVGA schematic • Linear-in-dB gain control though exponential variation of the tail current • Temperature compensation (PTAT control current ICTRL) • Parasitic path compensation (dummies Q9-Q10) for extended dynamic range • 46-GHz-fT 0.8-μm silicon bipolar process by STMicroelectronics
EXPERIMENTAL RESULTSGain control characteristic T = 30 °C VCC = 3 V, f = 400 MHz, Pin = -10 dBm
TO PROBE FURTHERRelated publications • F. Carrara and G. Palmisano, “High-dynamic-range VGA with temperature compensation and linear-in-dB gain control,” IEEE J. Solid-State Circuits, vol. 40, pp. 2019-2024, Oct. 2005. • F. Carrara, C. Santagati, and G. Palmisano, “High-dynamic-range VGA with temperature compensation and linear-in-dB gain control,” in Proc. IEEE Bipolar/BiCMOS Circuits and Technology Meeting (BCTM 2004), Montréal, Canada, Sept. 2004, pp. 184-187. • C. D. Presti, F. Carrara, and G. Palmisano, “Variable-gain up-conversion mixer with current reuse for 5-GHz W-LAN applications,” in Proc. European Conf. on Circuit Theory and Design (ECCTD 2005), Cork, Ireland, Aug. 2005, vol. 1, pp. 249-252.