Browse Prior Art Database

Time-Domain Thermo-Electric Cooler Controller with an Adaptive Integrator Gain

IP.com Disclosure Number: IPCOM000101564D
Publication Date: 2005-Mar-16
Document File: 2 page(s) / 257K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses a stable closed loop control to drive a programmable error gain amplifier. This amplifier creates a variable integrator gain that adapts to error conditions and enables an optimal loop dynamic for control to the thermo-electric cooler (TEC). Benefits include a solution that increases stability and does not require external components to set the loop bandwidth.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

 

Time-Domain Thermo-Electric Cooler Controller with an Adaptive Integrator Gain

Disclosed is a method that uses a stable closed loop control to drive a programmable error gain amplifier. This amplifier creates a variable integrator gain that adapts to error conditions and enables an optimal loop dynamic for control to the thermo-electric cooler (TEC). Benefits include a solution that increases stability and does not require external components to set the loop bandwidth.

Background

In networks with optical amplification, the temperature of the SOA or pump laser must be constant to provide temperature-independent amplification. The TEC is a device used for temperature control.

In order to drive the TEC, a thermistor is used to detect the temperature of the SOA or pump laser. The temperature is compared against the target temperature. The difference is then used to alter the current drive of the TEC. Thus, a negative feedback loop is formed (see Figure 1). All current TEC controllers employ an analog approach to realize this feedback control; the implementation of such a loop is divided into four parts: the loop control circuit, the H-bridge TEC driver, the TEC, and the thermistor circuit.

An important design condition for any feedback control is the stability. Looking into the TEC controller loop, the TEC and the thermistor introduce poles at a very low frequency (i.e. in the range of hundreds of Hertz). These two poles tend to be close to each other and vary during operation, leading to loop instability. One way to solve this problem is to introduce a dominant pole in the PI network so that the open loop gain at the non-dominant pole is well below 0dB. This means that the dominant pole has to be in the frequency range of tens of Hertz, or lower. To implement such a pole on c...