Low noise amplifier csd
The document summarizes a seminar presentation on low noise amplifiers (LNAs). It discusses that LNAs are key components for amplifying weak signals from antennas. It then outlines two design methods for LNAs - lumped parameter and distributed parameter. Lumped parameter treats active devices and input/output networks separately, while distributed parameter considers them together using Smith charts. It also discusses using matching networks between antennas and LNAs and between LNAs and mixers to provide proper terminations and ensure optimal noise performance, stability and power matching. Finally, it compares narrowband and wideband LNAs and their differences in circuit complexity, noise performance, and achieving bandpass amplification.
Low noise amplifier csd
- 1. Seminar on: Low Noise Amplifier Presented by: Miss Rina Ahire ME(E&C) 1
- 2. Contents: •Low Noise Amplifier •General philosophy •Lumped Parameters •Distributive Parameters •Matching N/W’s •Comparison between Narrowband & Wideband LNA
- 3. Low Noise Amplifier: • Key component of any low-noise amplifier coming off the antennas • Signal at that point: weak, good gain & noise performance are necessary
- 4. General Philosophy: LNA Design: Two methods 1. Lumped Parameter 2. Distributive Parameter
- 5. Lumped Parameter: •Stability, gain & noise analyzed: Bode/ Niquist plots •During design, active devices & i/p-o/p termination n/w’s treated separately •Here voltage & current- Primary variables -Two port representations(y, z, h or g parameter)
- 6. Distributive Parameter: •Considers the distributive nature of the ckts. & uses Smith charts •Both the active devices & i/p-o/p terminations are consider together •Power becomes the primary variable of interest •S-parameter based analysis- main tool
- 7. Matching Networks: 1. Objectives: • Provide proper terminations to the Analog filters- Between antenna & the LNA Between the LNA & the subsequent mixer • I/P matching n/w ensures optimum noise performance & stability at the i/p O/P matching n/w ensures stability at the o/p • I/P matching n/w: Proper power matching between the antenna & the LNA
- 8. 2 . Matching for Noise & Stability: Fig. Generalized LNA topology
- 9. 3. Matching for Power: Fig. (a) LNA using lumped parameter representation Fig(b) LNA with transformer matching at the i/p
- 10. Comparisons of Narrowband and Wideband LNA: Narrowband LNA Wideband LNA Having tuned matching n/w at Wideband matching n/w for i/p &o/p frequency response of the amplifier – flat at the o/p Circuit is simple Circuit is complicated Low noise performance Noise performance is poor Circuit performance is simple Circuit performance is poor Difficult to achieve bandpass Easy to achieve bandpass amplification amplification
- 11. Thank You