Transcript A Wide Locking Range Differential Colpitts Injection
LC-Tank Colpitts Injection-Locked Frequency Divider With Record Locking Range
S.-L. Jang, Senior Member, IEEE, S.-H. Huang, C.-F. Lee, and
M.-H. Juang, Senior Member, IEEE
Presenter: 楊 子 岳 2020/4/27 1
Abstract
• • • • • The ILFD is based on a VCO with
two embedded injection MOSFETs for coupling external signal
to the resonators.
The new VCO is
composed of two single-ended VCOs coupled with cross-coupled MOSFETs and a transformer.
Supply voltage of
1.5 V
, free-running frequency is tunable from
5.85 to 6.17 GHz
.
Incident power of
0 dBm
the
locking range is about 7.1 GHz (65.4%) from the incident frequency 7.3 to 14.4 GHz
. The ILFD has a record locking range percentage among published
divide-by-2
LC-tank ILFDs.
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Outline
• • • •
Introduction Circuit Design Measurement Results Conclusion
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Introduction
• • • The main concern for the
frequency divider design is large locking range with low power consumption
.
For
high speed and low power
operation LC-tank ILFD is the most suitable one among various types of frequency dividers because
operating frequency is determined by the resonant frequency
.
The ILFD is based on a new
VCO topology and two injection MOSFETs for coupling external injection signal to lock the VCO output signal.
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Circuit Design
• Schematic of a single-ended VCO and its equivalent LC resonator •Transistors (M5,M6) are configured to provide
negative resistance Rin
to
compensate for the tank loss
.
•The VCO provides two unbalanced outputs from the terminals of inductor L2 .
The varactors are used to tune VCO output frequency.
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Circuit Design
• Schematic of the proposed ILFD The cross-coupled transistors are used to couple the two single-ended VCOs to form a differential VCO and also provide a net negative resistance to the VCO to compensate for the loss due to the resistance in inductors, varactors, and injection MOSFETs.
L1,L2 are used to couple differentially the two single-ended VCOs.
k is the coupling coefficient 6
Circuit Design
• To obtain a wide-locking range: 1) firstly appropriately
choosing the location of injection MOSFET
is important, because the location
affects the efficiency of injection
.
2) Secondly, the
size of Min is optimized
, as the channel width
W of Min is increased
, the resonator
Q-factor is degraded
and the voltage swing of ILFD output decreases, these lead to the
increase in locking range
, however
if W is too large, the ILFD can not oscillate because two output ports of inductor are shorted.
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• Simulated
Circuit Design
Fig. 2. Simulated ac input gate voltage (bottom plot) of M and ac output voltages (top plots) of the buffers at injection-locked condition 2020/4/27 8
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Measurement Results
Fig. 4. Measured free running frequency tuning range of the ILFD circuit.
•
tunable from 5.85 to 6.17 GHz
with a
tuning voltage from 0 to 1.5 V
when dc bias voltage
Vinj is 1.5 V
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Measurement Results
Fig. 5. Measured and simulated relationship between input sensitivity and operating frequency at the supply voltage of 1.5 V At 1.5 V, a signal power
of 0 dBm provides a locking range of 7.1 GHz, from 7.3 to 14.4 GHz
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Measurement Results
Fig. 6. Measured phase noises of the free-running, injection-locked and injection-reference.
Injection power = 0 dBm, f = 6.13 GHz.
The phase noise of
free running oscillator at 1 MHz offset is about 104.5 dBc/Hz
. After
external power injection,the phase noise of ILFD is about 134.8 dBc/Hz
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Conclusion
• • • A new LC oscillator based ILFD has been proposed and fabricated in
TSMC 0.18 um
CMOS technology.
It consists of
two single-ended Colpitts VCOs coupled with cross-coupled MOSFETs and transformer
to form a differential circuit.
The
free-running frequency operates from 5.85 to 6.17 GHz
at the supply voltage of 1.5 V and power consumption of 7.65 mW.
The locking range is from 7.3 to 14.4 GHz which is up to 65.4%
when input power is 0 dBm.
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Thanks for your attention
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