After designing the tuned IF amplifier, I wanted a second IF amplifier that handled most of the receiver's gain. This ended up being more of a learning experience than I anticipated.

Continuing along with my HF superheterodyne receiver project, I designed and tested a tuned IF amplifier to feed the crystal filter. The tuned IF amplifier determines the receiver's ultimate performance by providing stable, high-gain amplification and precise bandpass filtering.

When designing a superheterodyne receiver, terminating mixers properly is important. This is especially important for the second mixer which is responsible for converting the intermediate frequency (IF) into audio. Even at this stage of the circuit, maintaining a consistent 50 Ω termination across all frequencies is required to minimizing distortion products and maintain a high dynamic range.

With my University Degree complete, I had much more free time to work on my superheterodyne reciever. Armed with more knowledge than my 2025 self, I decided it was worth redesigning most of it. Beginning with the frontend amplifier, I decided to try the cascode amplifier once again.

The previous cascode design was insufficient, so I redesigned it with much better results.

When testing the 20m superheterodyne reciever, there was a lot of noise generated by the previous frontend amplifier design, so I have decided to re-design the frontend amplifier. In this approach, I utilize the cascode configuration.

Having acquired more knowledge on amplifier configurations and properties, I redesigned the front-end amplifier. This time using a common base as the first stage, then common emitter as a second stage, with a common collector at the output to match the impedance to 50 ohms for the VNA measurements.

With the ongoing superheterodyne reciever project, I designed and simulated a recieve amplifier to amplify the signals coming from the antenna. I have chosen to use a bipolar junction transistor in the common emitter configuration as my amplifier.