Abstract: A bandgap voltage reference circuit for 0.35-.mu.m, 3-volt CMOS technology operates in an essentially temperature independent manner and having low supply voltages. The bandgap voltage reference circuit incorporates two operational amplifiers. One operational amplifier biases bipolar devices of the circuit and generates a PTAT voltage across a resistor, and the other operational amplifier buffers a voltage related to the PTAT voltage and a voltage across one bipolar device to generate the bandgap voltage reference. In one embodiment, the circuit includes a start-up circuit to ensure a stable and desired start-up state. A current bias may also be provided. The bandgap voltage reference of the second operational amplifier may also provide a regulated supply for the first stage of the circuit. The second operational amplifier also provides a buffered output to a resistor divider circuit to supply a voltage divider to generate voltages below the 1.24-volt bandgap voltage.

Abstract: A detector system employing a Viterbi algorithm includes an apparatus and method which constructs a double-state trellis structure for determining a most likely received symbol sequence with respect to an observed sequence of channel output samples. In the double state trellis, pairs of states are identified having equivalent branch metric values which also have a same decision during a path select, thus allowing these pairs of states to share a compare operation of a previous state metric. Consequently, to calculate an updated or current state metric value, an add, compare and select (ACS) circuit may compare only the previous state metric values to determine a minimum value for a transition between two states while combining each previous state metric value with its corresponding branch metric to provide an updated or current state metric value.

Abstract: A vector generator generates one or more pseudo-random noise PN sequences as matched-filter PN vectors for a matched-filter correlator of a code division, multiple-access (CDMA) demodulator. The period and clock of the local PN code sequence may be employed as a time reference, and each matched-filter PN vector has a known code-phase offset with respect to the local PN code sequence. Matched-filter PN vectors having a chip-length on the order of a data symbol period, such as 64-chip sequences, are generated within a short period of time compared to the period of the local PN code sequence. A state of the local PN code sequence is periodically captured from the local PN code sequence, which state is employed by a PN generator generating a similar PN code sequence but clocked at a higher rate. Consequently, a series of offset PN code sequences are generated in advance of the local PN code sequence.

Abstract: A system and method employing a rate 24/25 (0,9) code constructed in accordance with a data byte interleaved with a rate 16/17 (0,5) codeword formed from two data bytes limits the number of consecutive zeros seen by a channel to nine. The 16/17 (0,5) codeword is formed from the two data bytes in accordance with a set of pivot bits and a set of corrections for predefined code violations. The additional data byte is interleaved into the 16/17 (0,5) codeword by splitting the byte into a pair of portions and inserting the portions into the 16/17 (0,5) codeword at locations adjacent to predefined ones of the pivot bits. The rate 24/25 (0,9) code is suitable for magnetic or similar recording media and may be employed in partial response maximum likelihood read channels. A feature of the constructed code is a high transition density which allows for more frequent timing and gain control updates, which results in lower required channel input signal to noise ratio for a given channel performance.

Abstract: A fire suppression system for a process station, or chemical wet bench, employs an electro-optical fire detector and system controller to detect a fire in the process station. The system controller is coupled to a solenoid valve that is opened when a fire is detected by the fire detector, causing the fire suppressant to be delivered to a nozzle positioned in the process station. The nozzle atomizes the fire suppressant flowing through the nozzle so as to substantially cover the interior space of the process station with fire suppressant. The fire suppressant may be water provided by a local sprinkler system, and the nozzle is configured to atomize the fire suppressant when the fire suppressant is delivered to the nozzle under relatively low pressure.