XR-2122

XR-2122 Bell 212A Type Demodulator GENERAL DESCRIPTION The XR-2122 is designed to perform the complete Bell 212A type modem demodulator function. Both 1200 BPS differential phase shift keyed (DPSK) and 300 BPS frequency sh ift keyed carrier demodu lation is performed by the XR-2122. The 1200 BPS portion utilizes coherent demodulation. while the 300 BPS uses phase-locked loop techniques. For 1200 BPS operation. an internal 17 bit descrambler provides the descrambled output with the nondescrambled output also available. Automatic speed selection is performed by a handshake circuit. Carrier detect outputs are supplied for FSK data. PSK data. and conventional energy detection. A non-committed operational amplifier is supplied to provide receive carrier sensitivity tailoring. An automatic gain control circuit (AGC) assures wide dynamic input carr ier range. The XR-2122 is constructed using silicon gate CMOS technology. The X R-2122 is designed to operate off of a 1.8432 MHz clock inpu...