Adaptively configurable class-A/class-B transmit DAC for transceiver emission and power consumption control

• US 6,690,742 B2
• Filed: 03/05/2002
• Issued: 02/10/2004
• Est. Priority Date: 10/30/1998
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Chan, Kevin T.
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US10/091,099
• Publication Number:
  US 20020136315A1
• Time in Patent Office: 707 Days
• Field of Search: 375/285, 375/258, 375/257, 375/295, 375/259, 375/222, 375/219, 375/244, 341/126, 341/152, 341/153, 341/143
• US Class Current: 375/295
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers
• CPC Class Codes: H04B 3/32 Reducing cross-talk, e.g. by compensating
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: H04L 25/0276 Arrangements for coupling common mode signals
• CPC Class Codes: H04L 25/0282 Provision for current-mode coupling
• CPC Class Codes: H04L 25/0286 Provision of wave shaping within the driver wave shaping per se H04L25/03834
• CPC Class Codes: H04L 25/03834 using pulse shaping
• CPC Class Codes: H04L 25/08 Modifications for reducing interference; Modifications for reducing effects due to line faults ; Receiver end arrangements for detecting or overcoming line faults
• CPC Class Codes: H04L 25/14 Channel dividing arrangements , i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver

Abstract

A power efficient and reduced electromagnetic interference (EMI) emissions transmitter for unshielded twisted pair (UTP) data communication applications. Transmit data is processed by a digital filter. The digital filter output data is converted to a current-mode analog waveform by a digital-to-analog converter (DAC). The digital filter is integrated with the DAC binary decoder in a memory device such as a ROM with time multiplexed output. DAC line driver cells are adaptively configurable to operate in either a class-A or a class-B mode depending on the desired operational modality. A discrete-time analog filter is integrated with the DAC line driver to provide additional EMI emissions suppression. An adaptive electronic transmission signal cancellation circuit separates transmit data from receive data in a bidirectional communication system operating in full duplex mode. For a multi-transmitter system, timing circuitry staggers the time base of each transmitter to reduce the aggregate EMI emissions of the multi-transmitter system.

Claims

1. A method for analog discrete-time filtering of an output signal of a digital-to-analog converter for transmission over an unshielded twisted pair transmission line comprising the steps of:

dividing an input data sample period into two time segments; and

transmitting the output signal at a full amplitude for duration of the second time segment and transmitting the output signal at a portion of the full amplitude for duration of the first time segment.

2. The method of claim 1, wherein the first time segment and the second time segment are equal to half of the input data sample rate and the portion of the full amplitude is equal to half of the full amplitude.