Outline Phased-Array Receiver Architectures A 24GHz Integrated Phased-Array Receiver Measur
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* 24.075
- 24.175GHz for field disturbance sensors (FCC Part 15, Section 15.245) 24.0 - 24.25GHz for fixed and point-to-point operation (FCC Part 15, Section 15.249)
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
Signal-to-Noise Ratio Improvement
Baseband Processing None Severe High Low High
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
LO Phase Shifting Architecture
Heterodyne Version GRF GIF Homodyne Version G1
φ1
GRF GIF G2
+
φ1
φ2
A/D
φ2
+
A/D
GRF
GIF
Gn LO
φn
φn
• Compensate propagation delay by phase shifting the LO, • Ideal for narrowband channels, • Accuracy is inversely proportional to the bandwidth.
– More isolation between floors – Less delay spread for line-of-sight – Comparable excess path loss for line-of-sight
• Less than proportionate increase of power consumption in a narrowband integrated radio implementation
• Limiting factors in high speed wireless communications:
– Multi-path Fading – Co-channel Interference
• Multiple spaced antennas form statistically independent communications channels in a fading environment.
Hossein Hashemi1, Xiang Guan2, Ali Hajimiri2
1 University
of Southern California, Los Angeles, CA 2 California Institute of Technology, Pasadena, CA
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
Narrowband vs. Wideband
Signal constellations of a QPSK signal with 6dB SNR at each antenna input of an 8-path array at 24-GHz carrier frequency.*
d≈λ/2 λ wave-front
d= λ 300m/s ≈ = 15cm 2 2 × 1000Hz
d Processor
Delay
Delay
+
sound nalogy
Delay
Antenna 1 Antenna 2
• Compensate for air propagation delay in order to amplify or reject signals from certain directions. • Amplitude control allows for multiple spatial peaks and nulls.
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon
• Smaller wavelength
– Reduced antenna size and spacing (~ λ) – Lower effective antenna area (~ λ2)
λ1 > λ2
• Indoor channel characteristic in an office environment 1:
The 24-GHz Frequency Band
250 MHz
frequency 22GHz 24GHz 29GHz
Industrial, Scientific, Medical (ISM) / Unlicensed* Ultra Wide Band (UWB) for Vehicular Radar Systems
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
Outline
• Introduction • Phased-Array Receiver Architectures • A 24GHz Integrated Phased-Array Receiver • Measurement Results • Conclusion
– Receiver diversity – Transmitter diversity
• Phased array provides a directional communication channel. • Improvement increases with the number of antenna elements.
*
[dBm]
Assuming equal input signal and noise power levels and identical paths.
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
Advantages of Multiple Antennas
SIN,1 NIN,1 SIN,2 NIN,2
+
G1 SOUT
+
SOUT = G.n2.SIN NOUT = G.n.(NIN+NRX) SNROUT = n
NOUT
NRX,1
+
G1
NRX,2 SIN,n NIN,n
+
SIN NIN+NRX
G1
NRX,n
Example: n=8 , SNRIN=6dB , BW=250MHz , NF1-path= 10dB sensitivity = 10log[C/(I+N)] + 10log(kBTB) + NF = (6 + 9) + (-174 + 84) + 10 = -65 dBm
Outline
• Introduction • Phased-Array Receiver Architectures • A 24GHz Integrated Phased-Array Receiver • Measurement Results • Conclusion
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
H. Hashemi, X. Guan, and A. Hajimiri, “A Fully Integrated 24-GHz 8-Path Phased-Array Receiver in Silicon,” ISSCC 2004.
Phased-Array Principle
k θ Rejection of Amplification at undesired direction desired direction
