Optimized Signal Generation Circuit for Coded GHz Acoustic Microscope

We present a modulator circuit for our 0.9 GHz acoustic microscope, that employs a LTC5598 chip to provide a broad, high frequency bandwidth. Compared to [1], this modulator circuit features improved balancing and DC-coupling that allows a continuous band across the local oscillator frequency. A PLL circuit (ADF4351) creates a local oscillator signal. Since 900 MHz frequency is widely used, e.g. in cell phone networks, SNR can be improved by removing this external noise. We shielded the acoustic microscope electrically by assembling a metal casing for the T/R switch and the modulator.