A CMOS RF Front-End using Radiation Oscillator for Short-Range Wireless Communication Toru Mukai, Atsushi Iwata and Mamoru Sasaki Graduate School of Advanced Sciences of Matter, Hiroshima University E-Mail: {toru, iwa, sasaki}@dsl.hiroshima-u.ac.jp Introduction The recent downsizing of CMOS technology enables monolithic integrated millimeter-wave circuits applicable to sensor and communication systems. The combination of active devices with passive planar structures, including also antenna elements, allows single-chip realizations of complete millimeter-wave front-ends. This paper describes a simple architecture of quasi-millimeter-wave CMOS RF front-end. In the architecture, only one circuit block based on radiation oscillator can carry out whole functions in transceiver. In order to confirm the feasibility of the architecture, the prototype circuit has been designed and fabricated in a 0.18-μm CMOS technology. 100Mbps data rate and 8.11mW power consumption on 20GHz carrier frequency can be achieved. Architecture A. Electro-Magnetic Fed Patch Antenna Fig. 1 shows a structure of the RF front-end. A patch antenna is implemented above IC chip. Fig. 2 shows a relationship between radiation efficiency η and dielectric thickness t of typical patch antenna. λ0 is the free space wavelength. As shown in Fig. 2, t/λ0 thicker than 0.1 is required in order to achieve sufficient radiation efficiency. However, it is impossible to fabricate such a thick dielectric layer in conventional CMOS technology. In order to overcome the problem, patch and dielectric layer are stacked in post-process to ensure enough dielectric thickness. Only the ground plane of patch antenna is implemented with top metal layer in the CMOS technology. In order to feed the power from IC chip to the patch with no through-hole-via, an inductive coupling between the patch and a slot in the ground plane is employed. B. Radiation Oscillator Fig. 3 shows a circuit diagram of the radiation oscillator. In the oscillator, the antenna is used as both a radiator and a resonator. The cross-coupled MOSFETs M1 and M2 implement a negative resistance. C. On/Off Keying Modulation On/Off Keying (OOK) modulation is employed for digital communication. It is realized with switching two states, oscillation and non-oscillation, by MOSFETs M3 and M4. According to transmitting data, the gates of M3 and M4 are controlled and the circuit state is switched into oscillation or non-oscillation. D. Super-Regeneration In receiver operation, super-regeneration technique is employed, in order to amplify the received wave and demodulate the OOK signals. The negative resistance value of the cross-coupled MOSFETs M1 and M2 is tuned by the bias voltages Vgate and it is set to the critical point (which means the boundary between oscillation and non-oscillation). In the above condition, the oscillation starts if it receives RF signal having same frequency as the oscillator. A following simple circuit detects the oscillation and demodulates it to digital data As described above, the front-end circuit has a simple structure that merges many functions of oscillator, modulator, demodulator and radiator. Impedance mismatch and insertion loss in connections of several blocks are serious problems in millimeter-wave systems. The connectionless structure is very effective in millimeter-wave RF circuits. Circuit Configuration and Simulation Fig. 4 shows a simplified model of a radiation oscillator, for circuit design. Both the device and the antenna are modeled with Y-parameters because they are connected in parallel. "Ya = Ga + jSa" and "Yd = Gd + jSd" are admittances of the antenna and the device, respectively. The oscillation condition can be described as follows. A test chip was fabricated in a 0.18-μm CMOS technology. The chip micrograph is shown in Fig. 5. The butterfly shape slot in the top metal couples the device and the patch antenna, without any through-hole-via. Y-parameters of the antenna and the device designed in test chip are shown in Fig. 6. It is able to recognize that the oscillation frequency is 19.7 GHz, from the above analysis. The patch antenna is designed using 3-dimensional electro- magnetic solver. The electro-magnetic solver typically outputs only S-parameters. However, it cannot be used in transient circuit simulation. In the design, 7th order transfer function is calculated from the S-parameters and it is used as a time- domain antenna model. Fig. 7 shows a result of the SPICE transient simulation of the receiver. A situation is assumed, where the transmission distance and the data rate are 1.5m and 100Mbps, respectively. The digital data can be demodulated as shown in Fig.7. In this condition, power consumption of receiver circuit is 8.11mW. Specification of the test-chip is shown in Table I. G = G a + G d ≤ 0 S = S d + S a =0
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
A CMOS RF Front-End using Radiation Oscillator forShort-Range Wireless Communication
Toru Mukai, Atsushi Iwata and Mamoru SasakiGraduate School of Advanced Sciences of Matter, Hiroshima University
E-Mail: {toru, iwa, sasaki}@dsl.hiroshima-u.ac.jp
Introduction
The recent downsizing of CMOS technology enables monolithic integrated millimeter-wave circuits applicable to sensor and communication systems. The combination of active devices with passive planar structures, including also antenna elements, allows single-chip realizations of complete millimeter-wave front-ends. This paper describes a simple architecture of quasi-millimeter-wave CMOS RF front-end. In the architecture, only one circuit block based on radiation oscillator can carry out whole functions in transceiver. In order to confirm the feasibility of the architecture, the prototype circuit has been designed and fabricated in a 0.18-µm CMOS technology. 100Mbps data rate and 8.11mW power consumption on 20GHz carrier frequency can be achieved.
Architecture
A. Electro-Magnetic Fed Patch AntennaFig. 1 shows a structure of the RF front-end. A patch antenna
is implemented above IC chip. Fig. 2 shows a relationship between radiation efficiency η and dielectric thickness t of typical patch antenna. λ0 is the free space wavelength. As shown in Fig. 2, t/λ0 thicker than 0.1 is required in order to achieve sufficient radiation efficiency. However, it is impossible to fabricate such a thick dielectric layer in conventional CMOS technology. In order to overcome the problem, patch and dielectric layer are stacked in post-process to ensure enough dielectric thickness. Only the ground plane of patch antenna is implemented with top metal layer in the CMOS technology. In order to feed the power from IC chip to the patch with no through-hole-via, an inductive coupling between the patch and a slot in the ground plane is employed.B. Radiation Oscillator
Fig. 3 shows a circuit diagram of the radiation oscillator. In the oscillator, the antenna is used as both a radiator and a resonator. The cross-coupled MOSFETs M1 and M2 implement a negative resistance.C. On/Off Keying Modulation
On/Off Keying (OOK) modulation is employed for digital communication. It is realized with switching two states, oscillation and non-oscillation, by MOSFETs M3 and M4. According to transmitting data, the gates of M3 and M4 are controlled and the circuit state is switched into oscillation or non-oscillation.
D. Super-Regeneration In receiver operation, super-regeneration technique is
employed, in order to amplify the received wave and demodulate the OOK signals. The negative resistance value of the cross-coupled MOSFETs M1 and M2 is tuned by the bias voltages Vgate and it is set to the critical point (which means the boundary between oscillation and non-oscillation). In the above condition, the oscillation starts if it receives RF signal having same frequency as the oscillator. A following simple circuit detects the oscillation and demodulates it to digital data
As described above, the front-end circuit has a simple structure that merges many functions of oscillator, modulator, demodulator and radiator. Impedance mismatch and insertion loss in connections of several blocks are serious problems in millimeter-wave systems. The connectionless structure is very effective in millimeter-wave RF circuits.
Circuit Configuration and Simulation
Fig. 4 shows a simplified model of a radiation oscillator, for circuit design. Both the device and the antenna are modeled with Y-parameters because they are connected in parallel. "Ya = Ga + jSa" and "Yd = Gd + jSd" are admittances of the antenna and the device, respectively. The oscillation condition can be described as follows.
A test chip was fabricated in a 0.18-µm CMOS technology. The chip micrograph is shown in Fig. 5. The butterfly shape slot in the top metal couples the device and the patch antenna, without any through-hole-via. Y-parameters of the antenna and the device designed in test chip are shown in Fig. 6. It is able to recognize that the oscillation frequency is 19.7 GHz, from the above analysis.
The patch antenna is designed using 3-dimensional electro-magnetic solver. The electro-magnetic solver typically outputs only S-parameters. However, it cannot be used in transient circuit simulation. In the design, 7th order transfer function is calculated from the S-parameters and it is used as a time-domain antenna model.
Fig. 7 shows a result of the SPICE transient simulation of the receiver. A situation is assumed, where the transmission distance and the data rate are 1.5m and 100Mbps, respectively. The digital data can be demodulated as shown in Fig.7. In this condition, power consumption of receiver circuit is 8.11mW. Specification of the test-chip is shown in Table I.
G = Ga + Gd ! 0
S = Sd + Sa = 0
Conclusion
In this paper, we proposed a CMOS RF front-end architecture based on radiation oscillator. With employing OOK modulation and super-regeneration technique, circuits are simplified and power consumption is reduced. Data communication at 100Mbps on 1.5m distance has been confirmed by SPICE simulation. In the next step, we will measure the test chip, and demonstrate the validity of this architecture.
References
[1] P. Russer, “Si and SiGe Millimeter-Wave Integrated Circuits,” IEEE Trans. on Microwave Theory and Techniques, vol. 46, pp. 590-603, 1998.
Fig. 1 Structure of the RF Front-end.
Fig. 2 Radiation efficiency of patch antenna vs. dielectric thickness.
Fig. 3 Radiation oscillator.
Fig. 4 Simplified circuit model.
!r
t
Patch
Dielectric
Ground PlaneIC chip
post-process
slot (ground plane)
t / !0
0
0.2
0.4
0.6
0.8
1.0
00.01 0.02 0.03 0.04 0.05
efficiency
"
Vgate
M1 M2
M3 M4
Vin
Vgnd
Antenna
Antenna
Device
Yd = Gd + jSd
Ya = Ga + jSa
Fig. 5 Chip micrograph
(a) patch antenna
(b) device
(c) summation of (a) and (b)Fig. 6 Y-parameters of the patch antenna and the device.
Fig. 7 Simulation result of super-regeneration receiver (100Mbps, 1.5m).
Table. I Specification of the test-chip.
0G #0G $0G " 0G ! 0G %0G 0G #0G $0G " 0G ! 0G %0G
0m
! m
( m
#$m
#&m
!" 00m
!$00m
!#00m
0m
#00m
0G!4m
!3m
!2m
!1m
0m
!300m
!200m
!100m
0m
100m
10G 20G 30G 40G 50G 0G 10G 20G 30G 40G 50G
!4m
0m
4m
8m
12m
!300m
!200m
!100m
0m
100m
0G 10G 20G 30G 40G 50G 0G 10G 20G 30G 40G 50G
19.7GHz
30n0
2.0
0
2.0
0
2.0
0.6
0.9
－4.0
4.0 (uA)
(V)
(V)
(V)
(V)
50n 70n 90n 110n
(A) Received RF
(B) Oscillation control
(C) Super-Regeneration
(D) Demodulation
(E) Digital data
Technology 0.18µm CMOS (5M)
Power consumption
Transmitter (max) 20mW
ReceiverSuper-regeneration 8mW
Demodulation 110uWData rate 100Mbps
Transmission distance (max) 1.5mMaximum directivity 2.475Radiation efficiency 0.15
Ga Sa
SdGd
G S
A CMOS Front-End using Radiation Oscillatorfor Short-Range Wireless Communication
Toru Mukai, Atsushi Iwata and Mamoru SasakiGraduate School of Advanced Science of Matter, Hiroshima University
!r
t
Patch
Dielectric
Ground PlaneIC chip
post-process
slot (ground plane)
Background
Modeling and Analysis
Transmission Simulation
Downsizing of CMOS Technology
0G 10G 20G 30G 40G 50G 0G 10G 20G 30G 40G 50G
0m
4m
8m
12m
16m
!300m
!200m
!100m
0m
100m
0G!4m
!3m
!2m
!1m
0m
!300m
!200m
!100m
0m
100m
10G 20G 30G 40G 50G 0G 10G 20G 30G 40G 50G
!4m
0m
4m
8m
12m
!300m
!200m
!100m
0m
100m
0G 10G 20G 30G 40G 50G 0G 10G 20G 30G 40G 50G
19.7GHz
Conclusion and Future plan
Antenna Modeling7th-order Transmission Function
Circuit Modeling
calculated from the result of Electro-magneticSimulation (Ansoft HFSS)
Oscillating Condition
Suitable for Short-Range Communication
→ monolithic integrated millimeter-wave circuits
Capability of wideband CommunicationsMillimeter-wave
High atmospheric attenuation
Single-chip Transceiver Architecture
Radiation Oscillator
EM-Fed Patch antenna above IC chip・No-through-hole-via Feeding
・On/Off Keying・Super-Regeneration
Higher Radiation Efficiency
Small circuit area, Low Power
Radiation OscillatorUsing an antenna as a resonator
Many Functions in A Single Circuit
Varying bias voltages→ enables On/Off Keying Modulation and super-regeneration
Radiation Oscillator Circuit
Test-ChipSimulation Condition
Transmitter mode
30n0
2.0
0
2.0
0
2.0
0.6
0.9
－4.0
4.0 (uA)
(V)
(V)
(V)
(V)
50n 70n 90n 110n
Received Signal
Quench
Super-Regeneration
Demodulation
Output Data
0
2.0(V)
0
2.0(V)
0n 10n 20n 30n 40n
Oscillation Signal
Input Data
Transmitting Simulation Receiving Simulation
Receiver mode
Data Rate: 100Mbps
Set Vgnd to critical point
Distance: 1.5m
Input Data to Vin (OOK Modulation)
(between Oscillation and non-Oscillation)Input Quench to Vin (Super-regeneration)
Test-chip SpecificationTechnology : 0.18µm CMOS(5M)Power consumption transmitter : 20mW(max) super-regeneration : 8mW Demodulation : 110µW
Transmission distance : 1.5mData rate : 100Mbps
2.8mm
2.8mm
Radiation Oscillator
Ground-plane
Demodulator
Maximum directivity : 2.475Radiation efficiency : 0.15
AntennaPatch size : 1800µm × 2400µm
Dielectric thickness : 300µmSlot size : 500µm × 1000µm
Data communication at 100Mbps on 1.5m distance has been confirmed by simulation.A CMOS RF front-end architecture based on radiation oscillator was proposed.
We will measure the test chip, and demonstrate the validity of this architecture.
Chip Micrograph
Single-chip Transceiver
Vg
M1 M2
M3 M4
Vin
VgndアンテナAntenna
Ga Sa
Gd Sd
G S
G = Ga + GdS = Sa + Sd
Ga + Gd ≦ 0Sa + Sd = 0
Simplified circuit model
Antenna
Device
Yd = Gd + jSd
Ya = Ga + jSa
Antenna admittance
Device admittanceYd=Gd+jSdYa=Ga+jSa
Circuit Analysis
Related Documents
![EVgi - Cambridge University Pressassets.cambridge.org/97805211/73674/excerpt/9780521173674_excerpt.pdf · 5FTU 6 EVgi ' Ä * fjZhi^dch Ä GZVY i]Z fjZhi^dc# A^hiZc VcY lg^iZ V cVbZ](https://static.cupdf.com/doc/110x72/5c787f5609d3f2cb498bdab3/evgi-cambridge-university-5ftu-6-evgi-ae-fjzhidch-ae-gzvy-iz-fjzhidc.jpg)
