HTEL-2000A

Complete direct sequence spread spectrum burst transceiver in a single CMOS I.C.
 Programmable functionality supports many different operational modes
 Supports PN chip rate of over 11 Mchips/sec. in transmit and receive modes (STEL-2000A+45 only)
 Acquires within one symbol duration using digital PN Matched Filter
Two independent PN sequences, each up to 64 chips long, for distinct processing of the acquisition/preamble symbol and subsequent data symbols
Power management features
Optional spectral whitening code generation
Full or half duplex operation
100-Pin PQFP packaging

The STEL-2000A is a programmable single-chip spread spectrum transceiver. The device performs all the digital processing required to implement a fast acquisition direct sequence (i.e., pseudonoise- or PNmodulated) spread spectrum full- or half-duplex system using differentially encoded BPSK, QPSK, or p/4 QPSK. A block diagram of the STEL-2000A is shown In Figure 1, while the package style and pin configuration are shown in Figure 2. The STEL-2000A is available in two speed grades; the STEL-2000A+20 (20 MHz maximum clock frequency), and the STEL-2000A+45 (45.056 MHz maximum clock frequency).

The 45 MHz version features a high thermal conductivity package for superior heat dissipation, allowing the device to operate continuously at this speed.

The STEL-2000A integrates the capabilities of a digital downconverter, PN matched filter, and DPSKdemodulator into a single receiver, where the receiver input is the analog-to-digital converted I.F. signal. STEL-2000A transmit functions include a differential BPSK/QPSK encoder, PN modulator (spreader), and BPSK/QPSK modulator, where the transmitter output is a sampled digitally modulated signal ready for external digital-to-analog conversion (or, if preferred, the spread baseband signal may be output to an external modulator). These transceiver functions have been designed and integrated for the transmission and reception of bursts of spread data. In particular, the PN Matched Filter has two distinct PN coefficient registers (rather than a single one) in order to speed and improve signal acquisition performance. The STEL-2000A is thus optimized to provide reliable, high-speed wireless data communications.

The STEL-2000A operates with symbol-synchronous PN modulation in both transmit and receive modes. Symbol-synchronous PN modulation refers to operation where the PN code is aligned with the symbol transitions and repeats once per symbol. By synchronizing a full PN code cycle over a symbol duration, acquisition of the PN code at the receiver simultaneously provides symbol synchronization, thereby significantly improving overall acquisition time.