Antenna changeover switch for transmit-receive units in a mobile station

• US 20020006810A1
• Filed: 06/29/2001
• Published: 01/17/2002
• Est. Priority Date: 06/30/2000
• Status: Abandoned Application

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Schiller, Heiko
• Application Number:
  US09/896,606
• Publication Number:
  US 20020006810A1
• Time in Patent Office: Days
• US Class Current: 455/552.1
• CPC Class Codes: H01Q 21/30 Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes
• 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

Abstract

The invention relates to an antenna changeover switch for transceivers in a mobile station, designed for operation in at least two discrete HF transmission bands. For this purpose diode switches (D1 to D4) with HF impedance transformers are often used, which switch between channels of the GSM 900 network and channels of the DCS 1800 network. Owing to inadequate decoupling between the transceivers an appreciable portion of the transmitting signal from the active transceiver (TX1 or TX2) will arrive at the antenna terminal of the inactive transceiver. Therein in particular a portion coupled into the antenna terminal (A2) of the DCS 1800 transceiver by the GSM 900 transceiver can be so large that the currentless semiconductor components connected there generate harmonic waves. The problem is solved according to the invention in that controls (S1, S2) simultaneously conductively control the switch diodes (D1 and D2) in the GSM 900 transceiver and a switch diode (D4) located parallel to the signal input of the receiving unit (RX2) in the other transceiver with a bias current.

Claims

1. Antenna changeover switch for transmit-receive units in a mobile station with a first transceiver for an upper transmission band (DCS 1800) and at least one second transceiver for a lower transmission band (GSM 900) which separately have in each case a transmitting unit (TX1 or TX2) and a receiving unit (RX1 or RX2) and in addition contain:

a first switch diode (D1 or D3), located serially to the signal output of the transmitting unit (TX1 or TX2),

a second switch diode (D2 or D4) located parallel to the signal input of the receiving unit (RX1 or RX2),

an HF impedance transformer (L1 or L2), located serially to the signal input, which transforms a short circuit of the signal input into an open circuit for signal frequencies in the corresponding transmission band (GSM 900 or DCS 1800) and

controls (S1, S2) for actuating a transceiver, which during transmitting control the first and second switch diode (D1, D2 or D3, D4) in the active transceiver conductively by means of a bias current, so the signal output of the active transmitting unit (TX1 or TX2) is connected to a common transmit-receive antenna via an antenna terminal (A1 or A2) and a changeover switch (DF), and the signal input of the receiving unit (RX1 or RX2) is short circuited, wherein

the controls (S1) are constructed in such a way that they simultaneously conductively control the switch diodes (D1, D2) in the transceiver of the lower transmission band (GSM 900) and the switch diode (D4) located in the transceiver of the upper transmission band (DCS 1800) parallel to the signal input of the receiving unit (RX2).

2. Antenna changeover switch according to claim 1, characterised in that the impedance transformers (L1, L2) are different λ

/4 lines, which are substantially tuned to the average carrier frequency of the transmitting frequencies of the corresponding transmission band (GSM 900 or DCS 1800).

3. Antenna changeover switch according to claim 1, characterised in that at least between the antenna terminal (A1) of the transceiver for the lower transmission band (GSM 900) and the changeover switch (DF) is located a deep-pass filter (F1) which has a low attenuation for the fundamental wave of the transmitting signal in the lower transmission band (GSM 900), but already effectively suppresses the harmonic wave thereof.

4. Antenna changeover switch according to claim 1, characterised in that the bias currents for the switch diodes (D1-D4) are supplied by a switch signal of the respectively active transmitting unit (TX1 or TX2).

5. Antenna changeover switch according to claim 1, characterised in that the changeover switch is a semiconductor changeover switch.

6. Antenna changeover switch according to claim 1, characterised in that the changeover switch is constructed as a diplex filter (DF).