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
Riunione Annuale GE 2006
STMicroelectronics
Catania site
Ischia, 21-23 giugno 2006
INTRODUCTION
Requirements for WCDMA TX VGAs
TX VGAs are crucial in optimizing the channel capacity of
code-division systems like WCDMA
Main requirements are:


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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
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
CIRCUIT DESIGN
VGA schematic

Linear-in-dB gain control
though exponential variation
of the tail current
G
Riunione Annuale GE 2006
R I
RL IC11 RL AE11 I2



  exp C CTRL
RE I1
RE AE12 I1
 VT

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



Ischia, 21-23 giugno 2006
EXPERIMENTAL RESULTS
Gain control characteristic
T = 30 °C
VCC = 3 V, f = 400 MHz, Pin = -10 dBm
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
EXPERIMENTAL RESULTS
Performance summary
Parameter
Measured
performance
Dynamic range
77 dB
Gain error
± 1.5 dB
Frequency
0 – 600 MHz
ACLR
- 55 dBc
Output noise
Test conditions (*)
Full temperature and gain ranges
-152 dBm/Hz
5 MHz offset, HPSK modulation,
maximum gain, Pout = -10 dBm
Maximum gain
-168 dBm/Hz
Minimum gain
Supply voltage
2.7 V ~ 5 V
Current
consumption
3 mA
Minimum gain
6 mA
Maximum gain
(*) T = 30 °C, VCC = 3 V, f = 400 MHz unless otherwise specified
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
TO PROBE FURTHER
Related 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 upconversion 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.
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006