Basic op amp fundamentals can be found at https://Electronics.FoxPing.com/ under Chapter 4 - Analog Microcircuit Active Components. This website provides links to YouTube video clips.

The 2 stage LNA provides a degree of flexibilty not easily obtained from a single stage. That is improved dynamic range... input match providing a noise match and the ouput of the 2 nd stage to provide best P1dB match. The interstage match is designed to alter the input Z of device 1 to achieve noise match commensurate with congugate match while at the same time assisting on maximizing PAE as contributed by the second stage. Hence you need to know all the appropriate termination Z values to design a proper matched system. The majority of the design is centered on matching systems.

An instrument amp provides exceptional noise reduction.

Baseband low frequency or RF application?

Thank you for your answer Alan Victor , The aim is to design it to work at 6 GHz with narrowband matching with the aim of reducing the noise figure and maintaining gain above 10 dB.

Great. Then my initial response is in line with your question. You will need to address 3 key elements, input match, interstage match and output match. Other elements are bias and possibly AC feedback to control stability. It is key to meet the condition of unconditional stability in your design. In ADS, I would review the design templates for single stage low noise amplifiers which meet a specified transducer gain and noise figure. And then look at the design templates that meet a specified P1 dB. Understand that the majority of your work will be providing key termination impedances to meet your design objectives.

I should add, if you are looking at 6 GHz Narrow Band and moderate gain at 10 dB, a single stage is more than adequate. As a general rule, 10 to 12 dB gain per stage is typical. If you desired for example 22 dB gain over a BW of 15 or 20 % of fo.... then Yes... a multiple stage design is spot on.

Alan Victor would it be possible to refer me to a possible reference that explains the configuration of a Cascade CS-CS with a possible narrowband matching technique? Do we require only a single I/P matching and O/P matching for a typical design for the LNA? Thanks

Sure. There are quite a few excellent textbooks. Keysight and the older HP application notes are another resource. What technology are you investigating? Bipolar, CMOS, GaN, SiGe, etccc?

Alan Victor I am investigating a GaN HEMT device of 400um that has been characterized in an S2P model. Thanks a lot!

Alan Victor mainly I need to design a cascade CS-CS LNA with this device to meet requirements for gain, noise figure, and stability for 6 GHz frequency. Typical Narrowband matching I may use, however, I understood the configuration is popular but I need references that discuss it specifically since there are many references that are astray. Thanks

I would start with Microwave Transistor Amplifiers - Gonzalez... and by all means the IEEE XPLORE web site. I assume your design is a lumped element implementation and not a MMIC. However a study of the IEEE papers on MMIC designs that target C band and X band are excellent resources for such topologies. Will try to find such a paper.

Alan Victor actually I am more interested to design using lumped elements. However, I wanted your guidance regarding a typical Cascade CS-CS LNA to implement via ADS using the narrowband matching technique at input/output.

ok, input and output lumped matching... and there is the third match required at the interstage. The interstage match may be chosen to accomodate a complex to complex match between devices while at the same time assisting in alteration of the input Z of the first stage. The intent is to force the minimum noise match point of stage 1 to coincide closely with a congugate match on stage 1. The Z presented at stage 2 input will drive the stage 2 ouput most likely to a different Z than that which maximizes P1dB. Hence, you input match and noise figure could be quite good while the output match may be slghtly worse to acheve a specific high level of P1dB. Gauging this tradeoff can be vsualized with LOAD PULL CONTOURS provided by the device manufacturer. To get started and to appreciate the design details, I would divide the design into two pieces. One stage first targeting NF and the other P1dB.

Here is a fairly generic arrangement. You need to fill in the details for your 0.4mm device. There is significant info available within quite a few R&D publications. GL.

See attachments. An instrumentation amp provides the best CMRR (Common Mode Rejection Ratio). This website https://Electronics.FoxPing.com has details.

Dear Dr. Alan Victor , would it be possible to provide me with a reference that discusses the same? I appreciate the schematic but a reference would be really useful as well to get a hint about the calculation of the I/P and O/P matching with respect to the target specifications I need to adopt the GaN HEMT amplfiier for the LNA. Thank you

Textbook I mentioned earlier. Also see IEEE MTT VOL 38 ISSUE 2 FEB 90 pp 118-122.

HIGH FREQUENCY ELECTRONICS.... Analytic Graphical Method for LNA Design with Feedback... pub in 2010.

Again IEEE Xplore, has 1000's of papers treating this topic(s). There is no shortage of information out there. Study your ADS design templates and the data sheets from your device vendor.

See this paper in MTT Transactions:

A Graphic Design Method for Matched Low-Noise Amplifiers, Feb 1990