Design and implementation of an electrical interface for ring modulators using CPWs

Abstract:
This work presents the design and implementation of an electrical interface using coplanar waveguides (CPWs) to drive high speed ring modulators. To show this, first a small-signal model (SSM) of the modulator is developed by measuring its S11 response. The SSM is simulated with a conventional CPW to highlight the reflection problem emerging from the mismatch between the 50 Ω system reference and the high input impedance of the ring modulator which is around 1kOmega. The mismatch problem is mitigated by the proposed five-pin CPW design with ground-signalground- signal-ground (GSGSG) structure which terminates the reflection into an external 50 Ω termination. The proposed CPW demonstrates a measured S11 magnitude response below -15 dB throughout the frequency range of 25 GHz and -10 dB until 40 GHz.