Periodic switching circuit analysis using admittance matrices
Radio-frequency (RF) circuits employing periodically gated switches can be difficult to characterise in the frequency domain because they are time variant. The time variance causes frequency mixing and makes impedances difficult to define. A new method of frequency-domain analysis for periodic switching circuits is proposed in which a switch is represented by a matrix of admittance values. The columns of the admittance matrix correspond to voltage frequencies and the rows correspond to current frequencies, facilitating frequency translation effects in the circuit. The frequency domain is considered using a discretised set of harmonically related frequencies. The method is applied to the design and analysis of an RF switching mixer to demonstrate its advantages in calculating impedances and tuning the frequency response.