MF-PID Key Features
- 4 independent PID controllers with PLL capability
- LabOne PID Advisor with multiple DUT models, transfer function and step-response display, adjustable target bandwidth
- Auto-tune to minimize the residual PID error
- 50 kHz maximum loop filter bandwidth
- ±1024 π phase-unwrap for demodulator Θ data
- Low pass filter for derivative branch
MF-PID Upgrade and Compatibility
- Can be upgraded in the field, no hardware changes required
- Compatible with all other MF options
MF-PID Applications
- Laser frequency stabilization, fiber-noise cancelation
- Optical phase-locked loop, e.g. carrier envelope offset stabilization (CEO)
- Advanced AFM modes, e.g. Kelvin-Probe, Tip Protection
- MEMS measurements, e.g. gyroscope and resonator control
- Nano-mechanical oscillators
MF-PID Functional Diagram
Phase-locked loop (PLL) mode
One important application of the PID controllers is the phase coherent synchronization of an oscillator - the phase-locked loop or PLL. In the most simple case a modulated signal is provided to the lock-in amplifier and the PLL serves to recover and track the frequency of the signal. One PID would then take the phase information from one of the demodulators as an input and provide feedback to the frequency of one of the internal oscillators. It is important to know that this principle can also be reversed and the good phase noise properties of the internal oscillators can, for example, be transferred to an external setup such as a laser system.
The optional phase unwrapping in PLL mode extends the input range to ±1024π, meaning a reliable feedback at start-up and robust operation throughout.
PID Advisor, Auto-tune and automatic Set-point Toggle
AFM Tip Protection with the Threshold Unit
The MF Threshold Unit can be used in combination with the PID controllers. In addition to tracking demodulator amplitude and phase values, PID errors, PID shifts and PID output signals can also be monitored by the Threshold Unit. Whenever any of these signals leaves the adjustable safety corridors for a defined amount of time, logical outputs can be generated in order to take action and avoid damage on the setup. Tip protection in AFM applications is a typical example where this functionality is successfully used.
MF-PID Specifications
| Configuration | 4 PID controllers with PLL capability |
| PID input parameters | X, Y, R, and Theta from demodulator, auxiliary inputs 1 and 2, auxiliary outputs 1 to 4 |
| PID output parameters | Amplitude of signal outputs, signal output offset, internal oscillator frequencies, auxiliary outputs 1 to 4, demodulator phase offsets |
| Maximum PID bandwidth | up to 50 kHz |
| PID minimum propagation delay | 2.5 µs (Signal Input to Signal Output) |
| PID Advisor DUT models | All pass, Low pass 1st order, Low pass 2nd order, VCO/laser setup, resonator frequency, resonator amplitude, internal PLL |
| PID Advisor graphical display options | Bode magnitude, Bode phase, step-response, impulse-response; closed loop and open loop |
| Setpoint toggle rate | 64 mHz to 1 MHz |
| PID data streaming | PID error, PID shift and PID output values can be streamed at an adjustable rate, synchronized with demodulator data |
| PLL frequency range | 1 to 500 kHz; 1 to 5 MHz, requires MF-F5M option |
| PLL bandwidth | up to 50 kHz |
| Phase unwrap range | ±1024 π |