1. Radio Frequency and Analog Integrated Circuit
Design for Wireless and Broadband
Communication
Common-Gate Broadband Low-Noise Amplifier
By Paul Mushubi
2. LNA Objectives and Design Alternatives
2
Objective: To build an impedance-matched common-gate broadband LNA with at least
10 dB of gain, less than 5 dB of noise figure, and at least 5 GHz of bandwidth
Common-gate Common-source
• Does not require
reactive
components for
impedance matching
• Allows for wider
bandwidth
• Has modest noise
performance
• May use inductors
at the input for
inductive
degeneration and
tuning
• Has exceptionally
high gain and low
noise at the target
frequencies
5. High Frequency Cut-off and Gain Trade-offs
5
An inverse relationship between bandwidth and gain was observed in this data. As gain increased, the upper corner frequency lowered, and vice versa.
2
3
4
5
6
7
8
9
10
11
12
3
3.6
4.2
4.8
5.4
6
6.6
7.2
7.8
8.4
9
35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
MidbandGain[dB]
HighFrequencyCut-off[GHz]
Transistor Width [μm]
High Frequency Cut-off and Midband Gain vs.
Transistor Width
High Frequency Cut-off [GHz] Midband Gain [dB]
6. Gain and Noise Figure vs. Frequency
6
Mid-band Gain: 10 dB
Mid-band Noise Figure: 5.4 dB
High-frequency Cut-off: 4.6 GHz
7. Conclusion
7
• LNA is showing promising results and will be fabricated soon
• LNA may be used for a radio’s front end
Target Schematic Layout
Gain 10 dB 10 dB 9.2 dB
Noise Figure 5 dB 5.5 dB 6 dB
Bandwidth 5 GHz 4.7 GHz 2.4 GHz
