# Voltage and current sources

For an AC analysis, DC sources are short circuit (voltage source) or open circuit (current source), respectively. Accordingly, for a DC analysis, AC sources are short circuit (voltage source) or open circuit (current source), respectively. As these sources have no internal resistance, they are noisefree.

The MNA matrix of a current source is (with short circuit current flowing into node 1 and out of node 2):

 (9.141)

The MNA matrix of a voltage source is (with open circuit voltage across node 1 to node 2):

 (9.142)

The MNA matrix of a power source is (with internal resistance and available power ):

 (9.143)

The factor "8" is because of:

• transforming peak current value into effective value (factor two)
• at power matching the internal resistance dissipates the same power as the load (gives factor four).

The noise current correlation matrix of a power source equals the one of a resistor with resistance .

All voltage sources (AC and DC) are short circuits and therefore their S-parameter matrix equals the one of the DC block. All current sources are open circuits and therefore their S-parameter matrix equals the one of the DC feed.

This document was generated by Stefan Jahn on 2007-12-30 using latex2html.