Wireless Access

Schlumberger Technologies, Inc.

Sergio A Sanielevici

Burnell G West

Kenneth R Cioffi

Richard F Herlein

David K Cheung

Abhijit A Shah

Stephen F Lloyd

A multi-level quadrature (I/Q) mixer for use in a communication system such as a paging device, where the mixer includes first and second I/Q downconversions followed by demodulation. The first I/Q downconversion converts an I/Q signal pair to a first IF, and the second I/Q downconversion converts an I/Q signal pair to a second IF. The first IF may or may not be the center frequency depending on the number of subchannels in the single channel being downconverted.

Multi-level mixer architecture for direct conversion of FSK signals

A demodulation circuit providing for detection of multiple zero-crossings in an FSK signal. High data rate signals are demodulated by generating, for each pair of baseband signals I and Q, additional I and Q pairs which are phase shifted from the original I and Q pair. By generating zero crossing signals for the original baseband signals and for the phase shifted signals, additional zero crossings may be detected allowing demodulation of relatively high data rate modulated signals.

Direct demodulation method and apparatus

Driver circuits are provided which also serve as termination and clamp in an IC tester. When it is to drive a port of a device under test (DUT) between two predetermined voltage levels, the driver's I/O terminal is switched between two predetermined voltage levels with an output impedance that matches the transmission line between the driver circuit and the DUT. When the DUT's port is supplying an output signal, the driver circuit can be programmed to provide one of two types of termination. If the DUT's port is specified as capable of driving the load, the transmission line between the driver circuit and the DUT is terminated by switching the driver circuit's I/O terminal to a predetermined voltage level with an impedance of Z.sub.0. If the DUT's port is not specified as being capable of driving such a termination load, the driver circuit functions like a Z-clamp circuit.

Driver circuits for IC tester

Growing community of inventors

Los Altos, CA, United States of America

Sergio A Sanielevici