Transceiver circuit arrangement and method
A doubly balanced transceiver system having a transmit terminal (TX), a receive terminal (RX), and an an antenna terminal (ANTENNA), 180° hybrids ( 201, 240 ), 90° hybrids ( 204, 304, 235 and 335 ), a power amplifier ( 230, 330 ) and a RX/TX switch ( 220 ) for disabling the power amplifier so that signals received at the transmitter are reflected to the receive terminal (RX). The 180° hybrids ( 201, 240 ) preferably split and re-combine signals into parallel paths. A loopback test mode is preferably provided by use of an antenna isolation switch ( 302 ) to enable a power detect terminal (POWER_DETECT). This eliminates pricey and problematic GaAs switches, and allows the use of low cost silicon for the power amplifier. The doubly balance architecture also has the advantage of eliminating common-mode noise, and reflection problems with the PA gain stages. Additionally, greater power can be extracted from the power amplifier. Further the arrangement has less insertion loss compared to a GaAs switch. Also, dependant upon system specifications, it may be possible to eliminate harmonic filtering at the power amplifier output.
1. A transceiver circuit arrangement, comprising:
a first terminal for receiving a signal for transmission;
a second terminal for coupling to an antenna for transmission, and reception of signals;
a third terminal for producing a received signal;
a first 90 degree hybrid arrangement coupled to a first 180 degree hybrid arrangement for applying a 90 degree phase shift to signals applied thereto;
a second 90 degree hybrid arrangement coupled to a first 180 degree hybrid arrangement for applying a 90 degree phase shift to signals applied thereto;
a third 90 decree hybrid arrangement coupled to a second 180 degree hybrid arrangement for applying a 90 degree phase shift to signals applied thereto;
a fourth 90 degree hybrid arrangement coupled to a second 180 degree hybrid arrangement for applying a 90 degree phase shift to signals applied thereto; the first 180 degree hybrid arrangement coupled to the first terminal for applying a 180 degree phase shift and for splitting and re-combining signals applied thereto;
the second 180 degree hybrid arrangement coupled to the second terminal for applying a 180 degree phase shift and for splitting and re-combining signals applied thereto;
amplifier means coupled between the first and second terminals for amplifying signals received at the first terminal for transmission via the second terminal in transmission mode; and
transmit/receive switch means for disabling the amplifier means in receive mode whereby signals received at the second terminal are reflected to the third terminal.
2. The transceiver circuit arrangement of claim 1 , further comprising:
antenna isolation switch means coupled to the first 180 degree hybrid arrangement for selectively applying different outputs thereof and a same output thereof to the first and second 90 degree hybrid arrangements; and
a fourth terminal coupled to the second 180 degree hybrid arrangement for producing a power detect signal for use in loopback mode.
3. The transceiver circuit arrangement of claim 1 , arranged to reduce common mode noise.
4. The transceiver circuit arrangement of claim 1 , wherein the transceiver is a wireless data transceiver.
5. An integrated circuit comprising the transceiver circuit arrangement of claim 1 .
6. A method for a transceiver circuit arrangement, comprising:
providing a first terminal receiving a signal for transmission;
providing a second terminal coupled to an antenna for transmission and reception of signals;
providing a third terminal producing a received signal;
providing 90 degree hybrid means coupled between the first arid second terminals producing a 90 degree phase shift in signals passing therebetween;
providing 180 degree hybrid means coupled between the first and second terminals producing a 180 degree phase shift in signals passing therebetween, the 180 degree hybrid means comprising:
a first 180 degree hybrid arrangement coupled the first terminal applying a 180 degree phase shift and splitting and re-combining signals applied thereto, and
a second 180 degree hybrid arrangement coupled to the second terminal applying a 180 degree phase shift and spitting and re-combining signals applied thereto;
the 90 degree hybrid means comprising:
a first 90 degree hybrid arrangement coupled to the first 180 degree hybrid arrangement applying a 90 degree phase shift to signals applied thereto, a second 90 degree hybrid arrangement coupled to the first 180 degree hybrid arrangement applying a 90 degree phase shift to signals applied thereto,
a third 90 degree hybrid arrangement coupled to the second 180 degree hybrid arrangement applying a 91 degree phase shift to signals applied thereto, and
a fourth 90 degree hybrid arrangement coupled to the second 180 degree hybrid arrangement applying a 90 degree phase shift to signals applied thereto;
providing amplifier means coupled between the first and second terminals amplifying signals received at the first terminal for transmission via the second terminal in transmission mode; and
providing transmit/receive switch means for disabling the amplifier means in receive mode whereby signals received at the second terminal are reflected to the third terminal.
7. The method of claim 6 , further comprising:
providing antenna isolation switch means coupled to the first 180 degree hybrid arrangement selectively applying different outputs thereof and a same output thereof to the first and second 90 degree hybrid arrangements; and
providing a fourth terminal coupled to the second 180 degree hybrid arrangement producing a power detect signal for use in loopback mode.
8. The method of claim 6 , further comprising reducing common mode noise.
9. The method of claim 6 , wherein the transceiver is a wireless data transceiver.