Process-Dependence of the Even-Order Nonlinearity in Anti-Parallel Diode Pair Mixers

Diode mismatch in an anti-parallel diode mixer can generate a product at the second-harmonic of the local oscillator frequency. This product is referred to as the virtual local oscillator leakage. Variability in the fabrication process results in diode mismatch and is noticeable as an asymmetry in the current-voltage characteristics. Its impact on the virtual local oscillator leakage is analyzed by studying two populations of circuits with different diode sizes, fabricated using a six inch Gallium Arsenide heterojunction bipolar transistor process. Each population contained thirty circuits, within the same quarter-wafer.