A very simple baseline restorer for nuclear applications

We present a series of Baseline Restorer circuits (BLR) all based on a very simple and compact configuration. The circuits are able to withstand signals shaped as fast as 10ns or as slow as hundreds of ms. These BLRs are improved versions of an already existing solution that has shown outstanding performances. We have now introduced new features to the original configuration capable of improving the operation of the stationary condition of the stage that precedes the BLR output. This way the response of the circuit to the incoming signal is further improved. In addition, special attention has been paid to obtain large speed of response. Signal rates as large as 10MHz with large pile-up percentage are easily supported. This property is particularly suitable for the next generation of experiments at the large hadron colliders at CERN. One version of the described BLRs is presently used in the analog section of the trigger system of the experiment CUORICINO, an array consisting of 70 large mass bolometric detectors. For this experiment, the BLR is capable of guaranteeing a very precise baseline that allows to trigger very small signals for the Dark Matter study. Typical shaping times for this kind of bolometric signal are in the tens to hundreds of milliseconds range. The addition of a further simple circuit solution has permitted to suppress the problem of the re-trigger error coming from those large signals that present an undershoot, due to a non- perfect return-to-zero of the bolometric signals. Although having a different origin, this phenomenon can be thought as equivalent to a non-perfect pole-zero cancellation. The complete circuit diagrams of the BLR will be shown and the experimental results will be addressed in detail.