Transcript No Slide Title

Low-Noise Quadrature VCO for
HIPERLAN/2 in 0.18 m CMOS
Andreas Kämpe, Adiseno and H. Olsson
Radio Electronics Lab. LECS/IMIT.
Royal Institute of Technology, Sweden
•
The VCO operates at 2.0 GHz and has a tuning range of 600 MHz.
•
A frequency dubler is used to mix the 5.2 GHz RF, resulting in an IF of 1.2 GHz.
•
The phase noise is –121 dBc at 600 kHz offset frequency.
•
The VCO is based on a ring structure, offering quadrature outputs.
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The VCO is equipped with LC-tanks and is fully differential.
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The complete VCO has a buffer offering rail to rail output swing.
•
A chip is designed in a 0.18 m CMOS process.
System
Background
•
The use of an LC-tank in an oscillator reduces the Phase noise
significantly.
•
IF
RF
Integrated inductors eliminates the problem with large spread of
bondwire inductance.
•
x2
The disadvantage of integrated inductors are their low Q value
usually less then 10.
•
The frequency doubler
relaxes the VCO
constraints by reducing
the oscillation frequency
from 4 GHz to 2 GHz. It
also provides extra
isolation between the
mixer and the VCO.
Mixer
Frequency
doubbler
P LL
VCO
Each oscillator consists of complementary cross-coupled transistors.
Phase noise requirements for the VCO
•
The varactor consists of MOS transistors, this offers a larger tuning
range compared to a diode varactor.
Frequency offset
1.875 – 20 MHZ
20 – 50 MHz
> 50 MHz
Phase noise
-119 dBc
-139 dBc
-149 dBc
Circuits
I-
+
Q+
+
Osc
Osc
-
Out+
I+
Q-
Out-
Ring oscillator.
Buffer.
Q+
I+
Q-
I-
Ctrl+
Ou t-
In +
In -
Tail
Ctrl-
Complete VCO
Ou t+
 2
2
rms i n / f

L{ }  10 log 2
2
 q max 2 
Varactor.
Oscillator.
Simulation results
Tailcurrent
Power consumption excl buffers
Power consumption incl buffers
Tuning range
Phase noise (fc = 2.0 GHz, @ 600kHz)
Phase noise (fc = 2.0 GHz, @ 1.875kHz)
Phase noise (fc = 2.0 GHz, @ 20MHz)
Tuning range.
1.5 mA
5.4 mW
13.1 mW
1.59 – 2.14 GHZ
-117 dBc
-128 dBc
-147 dBc




0 
1
LC
Layout
3 mA
6 mA
11 mW
22 mW
22.5 mW
39.6 mW
1.60 – 2.22 GHz 1.68 – 2.35 GHz
-121 dBc
-123 dBc
-132 dBc
-135 dBc
-151 dBc
-152 dBc
Phase noise.
Low Noise Quadrature VCO
Abstract