Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

High-dynamic-range VGA with High-dynamic-range VGA with temperature compensation and temperature compensation and

linear-in-dB gain controllinear-in-dB gain control

Francesco Carrara and Giuseppe Palmisano

Radio Frequency Advanced Design Center (RF-ADC)

Università di CataniaFacoltà di IngegneriaDIEESCatania - ITALY

STMicroelectronicsCatania site

Sistemi Elettronici Integrati – B17

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

INTRODUCTIONINTRODUCTION Requirements for WCDMA TX Requirements for WCDMA TX

VGAsVGAs

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 linearity to comply with ACLR specification

TX VGAs are crucial in optimizing the channel capacity of code-division systems like WCDMA

Main requirements are:

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

CIRCUIT DESIGNCIRCUIT DESIGNVGA VGA schematicschematic 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

T

CTRLC

1

2

12E

11E

E

L

1

11C

E

L

V

IRexp

I

I

A

A

R

R

I

I

R

RG

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

EXPERIMENTAL RESULTSEXPERIMENTAL RESULTSGain control characteristicGain control characteristic

VCC = 3 V, f = 400 MHz, Pin = -10 dBm

T = 30 °C

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

EXPERIMENTAL RESULTSEXPERIMENTAL RESULTSPerformance summaryPerformance summary

Ischia, 21-23 giugno 2006Riunione Annuale GE 2006

TO PROBE FURTHERTO PROBE FURTHERRelated publicationsRelated 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.