The present invention generally relates to the field of transceivers for telecommunication systems, and particularly relates to transceivers for telecommunication systems that are efficient and inexpensive to produce.
Transceivers for telecommunication systems typically include a transmit path and a receive path. The transmit path typically includes a transmitter amplifier stage and a line driver, and the receive path typically includes a receiver amplifier stage that is coupled to the transmission line of the transmit path. Many transceivers provide for some type of noise rejection. For example, U.S. Published Patent Application No. 2003/0109239 published on Jun. 12, 2003 discloses a transceiver circuit that provides a second order high pass transfer function to reject out-of-band noise and distortion components.
As telecommunication systems become smaller and more ubiquitous, there continues to be a need for a transceiver circuit that is efficient and inexpensive to produce. There is further a need for a transceiver circuit that reduces required surface area in printed circuit boards. Moreover, during manufacture of such circuits it is often necessary to precisely trim certain resistors to ensure the accuracy of the circuits. Laser trimming of resistors consumes a significant portion of manufacturing time and costs. For example, U.S. Published Patent Application No. 2002/0151280 published on Oct. 17, 2002 discloses a transceiver circuit that provides a single matching impedance and includes resistors at the input stage of the transmitter path as well as the output stage of the receive path. The transceiver circuits disclosed therein, however, generally require that up to six resistors may need to be trimmed in each of the transmit path and the receive path, and that external capacitors may be required to couple the transmit circuit (which may operate at +12 volts to −12 volts) to the receive circuit (which may operate at +12 volts to ground).
There is a need, therefore, for a transceiver circuit that may be more efficiently and economically manufactured and processed.