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Final Design Review of a 1 GHz LNA / Down-Converter Charles Baylis University of South Florida April 22, 2005
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LNA Design Summary IBM SiGe Design Kit - 4 layers of metal Load resistance = 50 ohms (Filter) Feedback Resistor from collector to base stabilizes circuit, provides better matching For feedback configuration I C = 6 mA, R F = 460 ohms (initial – values were changed for final schematic.
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LNA Design Summary Power Consumption: Current through gain transistor + 1 mA reference current through current mirror. LC Match on Input/Output “De-Q” Inductors with resistors to improve bandwidth.
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LNA Schematic 9.3 pF 6.5 nH 83 pF 560 Ω 27 pF 1.4 kΩ 7.3 nH 4.5 pF 650 Ω Input Output Ground Vcc
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LNA Gain
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LNA Noise Figure
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LNA Input IP3
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LNA Input/Output Match
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LNA Compliance Reqt.Spec. MinSpec. MaxMinimumMaximumPass/Fail DC Current-10 mA-9.8 mAPass Gain14.5 dB17.5 dB16.5 dB16.9 dBPass Noise Figure -2.5 dB2.3 dB2.8 dBFail Input IP3-20 dBm--2.7 dBm-Pass Uncond. Stability ----Pass Input Return Loss 15.0 dB-15.7 dB20.9 dBPass Output Return Loss 15.0 dB- 30.3 dBPass
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LNA Compliance-Temperature Reqt.Spec. Min Spec. Max MinimumMaximumPass/Fai l DC Current-10 mA9.3 mA (-20˚)10.2 mA (70˚)Fail Gain14.5 dB17.5 dB16.0 dB (70˚)17.5 dB (-20˚)Pass Noise Figure -2.5 dB1.93 dB (-20˚)3.24 dB (70˚)Fail Uncond. Stability ----Pass Input Return Loss 15.0 dB-14.7 dB (-20˚)21.6 dB (70˚)Fail Output Return Loss 15.0 dB-14.0 dB (70˚)31.4 dB (-20˚)Fail
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LNA Compliance - Bias Reqt.Spec.MinSpecMaxMinimumMaximumPass/Fail DC Current-10 mA8.1 mA (2.7 V)11.6 mA (3.3 V) Fail Gain14.5 dB17.5 dB14.9 dB (2.7 V) 18.0 dB (3.3V) Fail Noise Figure -2.5 dB2.3 dB (3.3 V)2.9 dB (2.7 V) Fail Uncond. Stability ----Pass Input ReturnLoss 15.0 dB-12.9 dB (3.3 V) 22.2 dB (3.3V) Fail Output ReturnLoss 15.0 dB-10.7 dB (2.7 V) 30.3 dB (3 V) Fail
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LNA Layout LNA In Vcc LNA Out
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Mixer Design Approach f RF = 1 GHz, f LO = 860 MHz, f IF = 140 MHz Conversion gain = 9 dB = 2.82 Output Resistance = 50 Ω R L = 25 Ω Solve conversion gain equation for g m (gives starting value for current I C1 ).. Use LC network for input matching.
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Mixer Design Approach Noise figure improved by shrinking reference transistor for current mirror (and associated current). Also, beta helper transistor size was increased. As in LNA, “de-Q” inductors with shunt resistors to improve bandwidth.
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Mixer Schematic Input Out +Out - 7.03 kΩ 7 kΩ Vcc Ground 7.8 nH 3.7 pF 250 Ω 83 pF LO+LO-
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Mixer Conversion Gain
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Mixer Input IP3
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Mixer Input/Output Match Input Reflection CoefficientOutput Reflection Coefficient
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Mixer Noise Figure
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Mixer Compliance Specified Gain and Bandwidth Reqt.Spec. MinSpec. MaxMinimumMaximumPass/Fail DC Current-25 mA-12.4 mAPass Gain7.5 dB10.5 dB9.3 dB10.0 dBPass Noise Figure -11 dB9.0 dB10.7 dBPass Input IP3-15 dBm--12.95-Pass Input Return Loss 15.0 dB-15.2 dB26.4Pass Output Return Loss 15.0 dB-31.5 dB31.2 dBPass
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Mixer Compliance - Temperature Specified Gain and Bandwidth Reqt.Spec. MinSpec. MaxMinimumMaximumPass/Fail DC Current-25 mA11.47 mA13.3 mAPass Gain7.5 dB10.5 dB7.9 dB11.1 dBFail Noise Figure -11 dB7.1 dB11.59 dBFail Input Return Loss 15.0 dB- 31.7Fail Output Return Loss 15.0 dB-31.2 dB31.6 dBPass
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Mixer Compliance - Bias Specified Gain and Bandwidth Reqt.Spec. MinSpec. MaxMinimumMaximumPass/Fail DC Current-25 mA9.9 mA15.1 mAPass Gain7.5 dB10.5 dB8.2 dB10.7 dBFail Noise Figure -11 dB7.9 dB10.9 dBPass Input Return Loss 15.0 dB-13.7 dB45.4Fail Output Return Loss 15.0 dB-27.8 dB40.2 dBPass
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Mixer Layout Vcc Out - Out + LO - LO +- Mixer In
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LNA DRC and LVS
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Mixer DRC and LVS
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Conclusion Only LNA noise figure does not meet specification at nominal temperature and bias. Design has been run through multiple simulations to test its robustness.
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