The lab space has oscilloscopes, multimeters, and 5 V power supplies (on breadboard boxes) at each station. There are also soldering irons, several curve tracers, and an LCR impedance analyzer in the room. We only have available one high frequency signal generator. This signal generator is on one of the desks and must be time-shared among groups. There is a parts cabinet located on the other side of the lab that contains general components such as resistors and capacitors.
Three different components needed for this lab were handed out in class.
We have ordered additional transistors and variable capacitors, in addition to various fixed inductors (0.047 µH, 0.1 µH, 0.33 µH, 0.56 µH). We also have 1 µH tunable inductors. These parts will be made available in the lab. One other note is that the tunable inductors have limited tuning range. We advise you to use the tunable inductors as fixed inductors, and rely on the variable capacitors to tune your amplifier.
J310 Spice Model (SCS)
The J310 Spice model above is compatible with Spectre. This model may or may not be accurate as there are many different manufacturers of J310 transistors and there may be considerable variability in the transistor operating characteristics from lot to lot as well as part to part. I have tweaked the value of the threshold voltage, VTO, in the model based on DC measurements performed on one of the transistors. You are encouraged to verify and modify the model, as needed, by comparing simulation results to measured DC characteristics of your specific device. For example, the model currently does not model output conductance. You will want to either measure gds, or find its value from the datasheets at your operating point. Transconductance is another important DC device characteristic you should verify.
In order to use the model, copy the model file, jfet.scs, to your MIT server account. Then,
You should then be able to run simulations based on the J310 Spice model.
In this lab project, you will be required to simulate the noise figure of your amplifier. I will list the basic steps necessary to simulate noise figure using Spectre.
Keep in mind that we are using JFETs, not MOSFETs. They are similar except their threshold voltage is negative. The device will draw plenty of current with Vgs = 0. Put some thought into how you want to bias your devices.
As we mentioned in class, we encourage you to use lab equipment and parts available to you through your research labs. Most noticeably, we do not have a network analyzer there, which makes it difficult to measure your input match.
Please do your best to clean up after yourselves in the lab. We are using lab space and equipment reserved for other classes so let's not abuse our privileges.
Good luck and have fun!