GB2349527A

GB2349527A - External connector controlled impedance matching circuit

Info

Publication number: GB2349527A
Application number: GB0005487A
Authority: GB
Inventors: Michael Peter Messenger
Original assignee: Lucent Technologies Inc
Current assignee: Nokia of America Corp
Priority date: 1999-04-27
Filing date: 2000-03-07
Publication date: 2000-11-01
Anticipated expiration: 2020-03-07
Also published as: GB2349527B; GB0005487D0

Abstract

An external connector is connected to an electronic circuit which includes a port connected to a transmission line and an impedance matching circuit. The external connector enables different impedance matching for the transmission line to occur by allowing different terminals on the connector to be linked in a pattern that correspond to the required impedance matching. The transmission line may be part of a system using a base station and a cellular mobile telecommunications network.

Description

IMPEDANCE MATCHING IN ELECTRONIC EQUIPMENT This invention relates to electronic apparatus having a port for connection to a transmission line.

The background to the invention will be described with reference to a particular application. Other applications may readily occur to the reader.

It is desirable to manufacture base stations for cellular mobile telecommunications networks as standard items which can accommodate different requirements in different locations. One requirement is that the impedance of its uplink and downlink ports should match that of the respective transmission lines.

Against this background in accordance with one aspect of the invention there is provided electronic equipment having a port for connection to a transmission line, the port including an impedance matching network, responsive to different patterns of external connections applied between terminals of a connector to set the port impedance in dependence on the patterns.

In accordance with another aspect of the invention there is provided electronic equipment having an input port for connection to a transmission line to receive signals and having an output port for connection to a transmission line to send signals, the input port including an impedance matching input network, and the output port including an impedance matching output network, the networks being responsive to different patterns of external connections applied between terminals of a connector to set the input and output impedances in dependence on the patterns.

Standard equipment can be adapted on site during installation by the simple provision of one of a set of standard plug in adapters.

Preferably the networks are responsive to one pattern to match the input and output impedances to 75Q and to another pattern to match the impedances to 120Q. The networks may be responsive to yet another pattern to match the impedances to 100Q.

The invention extends to equipment in combination with an adapter comprising a complimentary connector and circuit means interconnecting terminals in a pattern to which the networks are responsive.

The connector is a preferably a D-type connector.

The invention also extends to an adapter including a D-type connector and circuit means interconnecting at least two terminals of the connector, the adapter carrying an indication of what impedance its use will obtain.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a plan view of an interface unit and a processor board of base station radio unit embodying the invention; Figure 2 is an end view of the interface unit of Figure 1; Figure 3 is a block diagram of the radio unit; Figure 4 is a schematic diagram of an adapter for use with the interface adapter of Figure 1; Figure 5 is a pictorial view of the adapter of Figure 2; and Figure 6 shows how Figures 6A, 6B, 6C and 6D assemble to provide a schematic circuit diagram of the interface unit of Figure 1.

Referring to the drawings, base station equipment comprises a radio unit 2 containing a transmitter 4, a power amplifier 6, a receiver 8, a signal processor other associated equipment (not shown) and a control processor 10 which has a main processor board 12 and an interface board 14. The interface board 14 contains all the interfaces necessary to connect the processor board to the outside world and is connected to the processor board by cable 16 and connector H09.

The interface board 14 is connected by uplink digital transmission lines to a land based telecommunications switching network (not shown) via D-type connector socket SK06, pins SK06-1 and SK06-2 being connected to a transmit transmission line via which signals are sent to the switching network. Pins SK06-4 and SK06-5 are connected to a receive transmission line via which signals are received from the switching network. Pins 7 and 8 receive clock signals and the remaining pins are grounded.

In order that two or more radio units can be daisy chained together, downlink connections are provided for one or more radio units via D-type connector SK04. Pins SK04-1 and SK04-2 are connected to a transmit transmission line via which signals are sent to the further radio unit (s) in the daisy chain. Pins SK04-4 and SK04-5 are connected to a receive transmission line via which signals are received from the further radio unit (s) in the chain. Pins 7 and 8 transmit clock signals and the remaining pins are grounded.

The data lines on pins SK06-1, SK06-2, SK06-4 and SK06-5 and SK04-1, SK04-2, SK04-4 and SK04-5, are protected by high voltage lighting protectors US1 to US4. The clock signals are connected straight through from SK06-7 and SK069 to SK04-7 and SK04-9. In order that radio units further on in the daisy chain are not put out of action in the event that this radio unit fails, relays RL1 to RL 4 are arranged to switch data lines on pins SK06-1, SK06-2, SK06-4 and SK06-5 through to pins SK04-1, SK04-2, SK04-4 and SK04-5, in the event of a fault being signalled on pin H09-25.

Low voltage surge protection is provided by fuses F1 to F4 and back to back zener diode pairs GR3 to GR10. DC isolation id provided by two transformers TR1 and two transformers TR2.

The data lines are clamped to 0 to +5v or-5 to Ov by diode pairs GR12 to GR18.

The impedance seen on the data lines at the connectors SK04 and SK06 is setable by configuring a network of resistors R5 to R22. The network is configured by interconnecting ports appearing on pins of a connector SK05.

In the present embodiment impedances of 75Q, 100Q and 120Q are provided. The interconnections are made by a configuration adaptor 18 shown in Figures 4 and 5.

The adapter 18 has a D-type connector PL05 complimentary to SK05. Two or more of the pins are connected by internal links 20 in a pattern which identifies to the processor what impedance is required. It is preferable that one of the permissible patterns is not no connections at all so that if an installer forgets to connect an adapter a fault will register.

The adapter is conspicuously marked with an indication 68 of the impedance its use will select.

The interconnections needed to configure the resistor network to provide the different impedances are shown in the following table: Variant Connect Pins E1-75 21-22 (75Q) 6-9 19-20 15-18 5-22 6-26 12-13 3-13 T1-100 1-2 (100#) 16-24 10-11 8-23 21-22 6-9 19-20 15-18 12-13 E1-120 14-22 (120Q) 6-25 3-13 Battery is connected to the processor board via a connector SK03 and cable 22.

Claims

1. Electronic equipment having a port for connection to a transmission line, the port including an impedance matching network, responsive to different patterns of external connections applied between terminals of a connector to set the port impedance in dependence on the patterns.

2. Electronic equipment having an input port for connection to a transmission line to receive signals from a land network and having an output port for connection to a transmission line to send signals to the land network, the input port including an impedance matching input network, and the output port including an impedance matching output network, the networks being responsive to different patterns of external connections applied between terminals of a connector to set the input and output impedances in dependence on the patterns.

3. Equipment as claimed in claim 1 or 2, wherein the networks are responsive to one pattern to match the input and output impedances to 75Q and to another pattern to match the impedances to 120Q.

4. Equipment as claimed in claim 3, wherein the networks are also responsive to a further pattern to match the impedances to 100Q.

5. Equipment as claimed in any preceding claim, in combination with an adapter comprising a complimentary connector and circuit means interconnecting terminals in a pattern to which the networks are responsive.

6. Equipment as claimed in any preceding claim wherein the connector is a D-type connector.

7. Equipment as claimed in any preceding claim constituting self contained base station equipment for a mobile cellular telecommunications network.

8. An adapter for use with equipment as claimed in any preceding claim, the adapter including a D-type connector and circuit means interconnection at least two terminals of the connector, the adapter carrying an indication of what impedance its use will obtain.