Lumped-element Mach-Zehnder interferometric modulators have been designed, fabricated in LiNbO3, tested and analyzed. These modulators had 3 dB bandwidths from 280 MHz to 2.75 GHz and Vπ's from 1 V to 4 V, respectively. A simple equivalent circuit is utilized to model the packaged modulator performance and results are compared with those measured using a swept-frequency technique. The model is seen to break down at the higher frequencies due to a frequency-dependent resistance and the electrode and parasitic inductances are seen to limit the overall modulator performance. The effects of varying the electrode capacitance, resistance, or inductance on modulator performance are demonstrated.