A 5.4mW GPS CMOS Quadrature Front End
based on a single-stage LNA-Mixer-VCO
Antonio Liscidini (1), Andrea Mazzanti (2), Riccardo Tonietto (3),
Luca Vandi (4), Pietro Andreani (4), and Rinaldo Castello (1)
(1)
(2)
(3)
(4)
Università degli Studi di Pavia, Pavia, Italy
Università di Modena and Reggio Emilia, Modena, Italy
STMicroelectronics, Pavia, Italy
Technical University of Denmark, Kgs. Lyngby, Denmark
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Mixer inside LC Oscillator
Vout (f)
Vout
M2
LC Filter
f0
f
t
attenuates the low
frequency components
of Vout
Id M1 (f)
Vg
bias current is naturally
down-converted at IF
• LC tank dramatically
M3
t
• Any RF signal in the VCO
M1
DC
f0
f
Problem:
to sense
the down-converted
current
signal
Howhow
sensing
the downconverted current
signal
preserving
oscillation
without
perturbing
the oscillator ?
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Double Switching Pairs Self Oscillating
Mixer (SOM)
Iout
1/fLO
IRF
M3
M2
- IRF
C
IF Load
Bias
M5
Iout
M1
Vin
M4
Bias
IRF
t
• All RF signal current is
down converted leading:
Iout 2
 gm 1
Vin

Semi-period with M2 and M4 on
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
LNA-Mixer-VCO (LMV) Cell
VCO
• LNA is implemented reusing M1 in a inductive
degenerated topology.
M3
M2
Mixer
C
IF Load
Bias
M4
M5
Bias
• Three transistor stacked
but minimum VDD is 1 VTH
plus 3 VOV
Lg
M1
Ls
LNA
Vin
Riunione Annuale GE 2006
LNA, Mixer and VCO
share bias and devices
Ischia, 21-23 giugno 2006
LMV Cells in Quadrature
I-
I+
M2I
Q+
Q-
M3I
M7I
Q-
Q+
M6I
I-
M2Q
M3Q
M7Q
I+
M6Q
Ibias
Ibias
C
C
IF Load
IF Load
M5I
M5Q
M4I
M4Q
Lg
Vin RF
M1I
I Path
M1Q
Ls
Q Path
Traditional cross-coupling topology for quadrature generation
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
GPS Low IF Quadrature Receiver
Quadrature LMV cells (2.5mA)
Mixer I
Iout IF I
Virtual Ground (2mA)
+
LNA
VinRF
VoutIF I
VCO
0/90°
PLL
Iout IF Q
+
-
VoutIF Q
Mixer Q
GPS quadrature Front-End: Low IF architecture at 4MHz
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006
Conclusions
•
The functionalities of RF amplification, mixing and LO
generator were successfully merged in a single stage.
•
The LMV cell represents a competitive solution to reduce
power consumption, compatible with low voltage supply.
•
The LMV cell was advantageously used in a very low
power GPS quadrature front-end.
Riunione Annuale GE 2006
Ischia, 21-23 giugno 2006