Features

• For use in OPLL
• Parallel PID
• Nested or bypass topology
• Feedforward and ramp inputs
• Loop polarity selector
• DC-voltage control of the P-action
• Presettable integrator
• Straightforward interface
• Additional loop-shaping stage
• Pure analog processing – free of digital noise
• EMI noise immunity
• Schematic diagrams included
• Ideal for rapid prototyping

Overview

The SMB30 module is an electronic board for use in Optical Phase-Locked Loop (OPLL) applications where the frequency detuning between two laser sources requires tight and quick control.
This board is a PID compensator designed for the piezo actuator of the laser source. In such applications, the low-frequency path is used to desaturate the high-speed loop that controls the fast frequency actuator over a wide bandwidth. The SMA30 is designed to work with the RF Frequency Mixer (SMA10) and High-Speed Compensator (SMA20)  modules. While the SMA30 output is able to drive low-voltage capacitive loads, an external piezo driver may be required for high-voltage actuators.
The SMA30 module gives a complete control of the loop filter operation for most demanding users. All analog inputs use differential pairs to avoid ground-loops. The loop polarity is set using a remote control or a local switch and the loop gain is adjusted over 80 dB using either a front panel trimmer or a DC-voltage. For lock-acquisition purposes, the integrator output of the PID can be precisely controlled by the user. A ramp input is provided to sweep the frequency during the open-loop operation and a feedforward input offers a useful control of the fast actuator such as frequency jumps or closed-loop measurements. Additional filter and equalizer stages allow the designer to shape the loop gain more acurately when low-frequency resonances of the piezo actuator can lead to closed-loop oscillations.
Like all SM-Series modules, the SMA30 is shipped with the schematic diagrams of its  electronic circuitry providing all required information for advanced users.