Enhanced time division duplexing (TDD) transceiver circuitry

• US 6,591,086 B1
• Filed: 04/24/2000
• Issued: 07/08/2003
• Est. Priority Date: 04/24/2000
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Telaxis Communicatoins Corporation (Proxim Wireless Corporation)
• Inventors: Pleasant, Wayne E.
• Primary Examiner(s): VUONG, QUOCHIEN B
• Application Number:
  US09/557,242
• Time in Patent Office: 1,170 Days
• Field of Search: 455/24, 455/63, 455/67.1, 455/67.3, 455/78, 455/82, 455/83, 455/19, 455/226.1, 455/226.2, 455/296, 455/269, 455/280, 455/283, 455/284, 455/287, 370/276, 370/277, 370/278, 370/280, 370/282
• US Class Current: 455/78
• CPC Class Codes: H04B 1/48 in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter H04B1/46 takes precedence
• CPC Class Codes: H04B 1/52 Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
• CPC Class Codes: H04B 1/56 with provision for simultaneous communication in two directions

Abstract

A communication transceiver circuit intended for operation in a Time Division Duplex (TDD) system. The configuration eliminates the need for transmit-receive switches and the circuitry needed to operate them. Instead, a three port circulator is used to couple a transmitter section and receiver section to a common antenna. A signal power detector and blanking circuit are coupled to the receiver section input and arranged to generate a blanking signal for an input receiver amplifier. This disables the receiver during conditions when power reflected back through the antenna and circulator would otherwise saturate the receiver. In a preferred environment, a second circulator is connected to an intermediate frequency (IF) side of the transceiver together with a pair of isolators to permit the transceiver to be connected to IF equipment with a single cable.

Claims

1. A transceiver apparatus for transmitting and receiving radio signals in a time division duplex (TDD) system, the apparatus comprising:

a transmitter section comprising at least a transmitter amplifier coupled to accept an intermediate frequency (IF) transmitter input signal and provide a radio frequency (RF) transmitter output signal;

a receiver section comprising at least a receiver amplifier coupled to receive an RF receiver input signal and to provide an IF receiver output signal;

an RF circulator, having a first port connected to receive the transmitter output signal, a second port connected to provide the RF receiver input signal, and a third port for coupling to an antenna;

a detector, connected to the receiver section to detect when a power level associated with the RF receiver input signal exceeds a predetermined power level; and

a blanking circuit for disabling the receiver amplifier when the detector determines that the RF receiver input signal exceeds a predetermined power level.

2. An apparatus as in claim 1 wherein the detector additionally comprises a directional coupler.

3. An apparatus as in claim 1 wherein the blanking circuit controls a supply voltage of the receiver amplifier.

4. An apparatus as in claim 1 additionally comprising:

a transmitter isolator disposed before the transmitter section, to provide the IF transmitter input signal.

5. An apparatus as in claim 1 additionally comprising:

a receiver isolator disposed after the receiver section, coupled to receive the IF receiver output signal.

6. An apparatus as in claim 1 additionally comprising:

an IF circulator, having a first port connected to receive the IF receiver output signal, a second port connected to provide the IF transmitter input signal, and a third port providing a transceiver input-output port.

7. An apparatus as in claim 1 additionally comprising:

a splitter having a first port connected to receive the IF receiver output signal, a second port connected to provide the IF transmitter input signal, and a third port providing a transceiver input-output port.

8. A apparatus as in claim 1 wherein the transmitter and receiver sections operate at a radio frequency carrier in a Local Multipoint Distribution Service (LMDS) band.