Chapter 4: Simulation and Component Models

Questions:

1. What are the limitations of s-parameter representation of MMIC component elements?

2. How are the individual MMIC components characterized?

3. What is the "lumped-element" approximation?

4. How do the parasitic elements differ from the prime element in an equivalent circuit model?

5. What extra requirements does nonlinear simulation place on the models?

6. Why would an MMIC use 3D EM simulation?

7. What effect will placing a bend in a transmission line have on the electrical performance of the transmission line?

Answers:

1. It ignores close components that not connected to its ports, and extrapolation of the data beyond the frequencies measured is unpredictable.

2. The components are produced with multiple geometries between RF-On-Wafer pads and lengths of feed transmission line using a characterization mask-set, and their s-parameters are measured RF-On-Wafer.

3. The dimensions of the component are less than one-tenth of the wavelength of the highest signal frequency in the circuit.

4. The prime element is the dominant characteristic of the component, and the parasitic elements represent second-order effects, such as loss and fringing capacitance.

5. The model must be valid at dc and at the higher harmonic frequencies at which the nonlinear simulation operates.

6. To predict coupling effects between unconnected components, wavelength-related effects, and other modes of propagation.

7. It will change the effective electrical length of the transmission line.