GB2475645A - Field effect transistor - Google Patents

Field effect transistor Download PDF

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Publication number
GB2475645A
GB2475645A GB1103577A GB201103577A GB2475645A GB 2475645 A GB2475645 A GB 2475645A GB 1103577 A GB1103577 A GB 1103577A GB 201103577 A GB201103577 A GB 201103577A GB 2475645 A GB2475645 A GB 2475645A
Authority
GB
United Kingdom
Prior art keywords
field effect
source
effect transistor
drain
signal line
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB1103577A
Other versions
GB2475645B (en
GB201103577D0 (en
Inventor
Ronald Arnold
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RFMD UK Ltd
Original Assignee
RFMD UK Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GBGB0612794.8A external-priority patent/GB0612794D0/en
Application filed by RFMD UK Ltd filed Critical RFMD UK Ltd
Publication of GB201103577D0 publication Critical patent/GB201103577D0/en
Publication of GB2475645A publication Critical patent/GB2475645A/en
Application granted granted Critical
Publication of GB2475645B publication Critical patent/GB2475645B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/10—Modifications for increasing the maximum permissible switched voltage
    • H03K17/102—Modifications for increasing the maximum permissible switched voltage in field-effect transistor switches
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/40—Electrodes ; Multistep manufacturing processes therefor
    • H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
    • H01L29/423—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions not carrying the current to be rectified, amplified or switched
    • H01L29/42312—Gate electrodes for field effect devices
    • H01L29/42316—Gate electrodes for field effect devices for field-effect transistors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/16—Modifications for eliminating interference voltages or currents
    • H03K17/161—Modifications for eliminating interference voltages or currents in field-effect transistor switches
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
    • H03K17/687—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors
    • H03K17/693—Switching arrangements with several input- or output-terminals, e.g. multiplexers, distributors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/44—Transmit/receive switching
    • H04B1/48—Transmit/receive switching in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
    • H03K17/687—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors
    • H03K2017/6878—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors using multi-gate field-effect transistors

Landscapes

  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Ceramic Engineering (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Electronic Switches (AREA)

Abstract

A field effect transistor comprising: a source 3, a drain 4, and a plurality of gates 15, 17 , wherein the source and drain comprise a plurality of source and drain fingers respectively. The FET may be used as an antenna switch in a time division multiple access method for GSM and UMTS mobile phones.

Description

A Field Effect Transistor
This invention relates to a field effect transistor. More particularly, but not exclusively, the present invention relates to a field effect transistor having a plurality of gates, at least one being connected to a signal path extending between source and drain, the signal path including a resistor, the gates on each side of the connected gate not being connected to the signal path.
Antenna switches are used in applications requiring a time division multiple access method, for example GSM and UMTS cellular phones. Series shunt configurations are often used, with a single pole and several throws, the series devices connecting alternatively either of a receive or transmit port to the single pole, and the shunt devices isolating the non-used ports.
Field effect transistors are used to realise the series or shunt devices, the input being the drain and the output the source, or vice-versa. The signal passes through the conductive channel.
When reaching the single pole, the signal "sees" one or several OFF arms in parallel. In order to transmit high power signals such as GSM at its nominal maximum power and in order to maintain a low bias voltage to drive the switch, the voltage swing present at the pole must not turn on the FET present in the OFF arm. Several FETs are therefore used in series in order to spread the high voltage across a high number ofjunctions and the junctions are kept at a floating bias.
However, each of the FETs constituting the OFF arm can be modelled by a highly non linear shunt capacitance, thus introducing non linearities in the switched signal.
Accordingly, in a first aspect the present invention provides a field effect transistor as claimed in claim 1.
The field effect transistor according to the invention can be employed as part of a linear antenna switch with the signal input and output ports being connected to the source and drain respectively (or vice versa).
Preferably, the connection line comprises a resistor.
Preferably, a signal line resistor is arranged between source and node.
Alternatively or additionally, a signal line resistor is arranged between drain and node.
Preferably, a plurality of gates are connected to the signal line by connection lines, the signal line and connection lines joining at nodes, the plurality of gates being selected such that each connected gate has adjacent gates on each side not connected to the signal line.
Preferably, at least some of the connection lines comprise resistors.
More preferably, each of the connection lines comprises a resistor.
At least one signal line resistor can be arranged between nodes in the signal line.
Alternatively, the nodes can be short circuited together by the signal line.
Preferably, the source and drain comprise a plurality of source and drain fingers respectively, the source and drain fingers beings interdigitated and spaced apart to define a meandering path therebetween, each gate comprising a gate strip extending along the meandering path.
The present invention will now be described by way of example only and not in any limitative sense with reference to the accompanying drawings in which Figure 1 shows a linear antenna switch arm according to the invention; Figure 2 shows a further embodiment of a linear antenna switch arm according to the invention; Figure 3 shows a further embodiment of a linear antenna switch arm according to the invention; Figure 4 further embodiment of a linear antenna switch arm according to the invention; and Figure 5 further embodiment of a linear antenna switch arm according to the invention.
Shown in Figure 1 is a linear antenna switch arm 1 according to the invention. The linear antenna switch arm 1 comprises a field effect transistor 2 which in turn comprises a source 3 and a drain 4 on a substrate (not shown). The source 3 and drain 4 comprise a plurality of source and drain fingers 5,6 respectively. The source and drain fingers 5,6 are interdigitated and slightly spaced apart to define a meandering path 7 therebetween. Extending along the meandering path 7 are a plurality of electrically conducting gate strips 8. The gate strips 8 have a rectifying effect. A change in voltage on a gate strip 8 causes a change in a depletion layer beneath the gate strip 8 so changing current flow between source 3 and drain 4 as is known.
A signal line 9 extends between source 3 and drain 4. The centre gate strip 8 is connected to the signal line 9 by a connection line 10, the join between the connection line 10 and signal line 9 comprising a node 11. The gates 8 on either side of the connected gate 8 are not connected to the signal line 9. The gate 8 connected to the signal line 9 is allowed to float.
The remaining gates 8 are connected to a control line 12 via resistors 13. The signal line 9 comprises a first signal line resistor 14 between source 3 and node 11 and a second signal line resistor 15 between drain 4 and node 11.
The circuit shown in Figure 1 can act as a linear antenna switch arm 1 with signal input and output ports connected to the source 3 and drain 4 respectively (or vice versa).
Shown in Figure 2 is a further embodiment of a linear antenna switch arm 1 according to the invention. This embodiment is similar to that of Figure 1 except it comprises five gate strips 8 rather than three. Other embodiments having different numbers of gate strips 8 are possible.
Shown in Figure 3 is a further embodiment of a linear antenna switch arm 1 according to the invention. As with the embodiment of figure 2 the field effect transistor 2 comprises five gate strips 8. Rather than the central gate strip 8 being connected to the signal line 9 it is the two gates 8 adjacent to the central gate 8 which are connected to the signal line 9 by connection lines 10. The connection lines 10 are connected to the signal line 9 at two nodes 11. In addition to the signal line resistors 14,15 of the first and second embodiments, this embodiment comprises a further signal line resistor 16 between nodes 11.
Shown in Figure 4 is a further embodiment of a linear antenna switch arm 1 according to the invention. This embodiment is similar to that of Figure 3 except the signal line resistor 16 between nodes is replaced with resistors 17 in the connection lines 10 as shown. The nodes 11 are effectively short circuited together by the signal line 9.
Shown in Figure 5 is a further embodiment of a linear antenna switch arm 1 according to the invention. This embodiment is similar to that of Figure 4 except the resistor 14 between source 3 and node 11 is removed. In an alternative embodiment the resistor 15 between drain 4 and node 11 is removed.
Other embodiments having different numbers of gates and numbers of gates connected to the signal line are possible provided that the gates on each side of a connected gate are not connected to the signal line.
Similarly, other arrangements of resistors in the signal and connection lines are possible. In the embodiments shown in Figures 4 and 5 all of the connection lines include resistors. In alternative embodiments not all of the connection lines comprise resistors, these are replaced by signal line resistors.

Claims (7)

  1. Claims1. A field effect transistor comprising:a source, a drain, and a plurality of gates, wherein the source and drain comprise a plurality of source and drain fingers respectively.
  2. 2. The field effect transistor of claim 1 wherein the source and drain fingers are interdigitated and spaced apart to define a meandering path therebetween.
  3. 3. The field effect transistor of claim 2 each gate comprising a gate strip extending along the meandering path.
  4. 4. The field effect transistor of claim 1, 2, or 3 wherein the plurality of gates comprises at least five gates.
  5. 5. The field effect transistor of claim 3 wherein each gate strip has a rectifying effect.
  6. 6. The field effect transistor of claim 3 or 5 wherein a change in voltage on a gate strip causes a change in a depletion layer beneath the gate strip so changing current flow between the source and drain.
  7. 7. A field effect transistor substantially as hereinbefore described.
GB1103577A 2006-06-28 2007-06-26 A field effect transistor Expired - Fee Related GB2475645B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB0612794.8A GB0612794D0 (en) 2006-06-28 2006-06-28 A linear antenna switch arm and a field effect transistor
GB0712385A GB2439642B (en) 2006-06-28 2007-06-26 A linear antenna switch and a field effect transistor

Publications (3)

Publication Number Publication Date
GB201103577D0 GB201103577D0 (en) 2011-04-13
GB2475645A true GB2475645A (en) 2011-05-25
GB2475645B GB2475645B (en) 2011-10-26

Family

ID=43969380

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1103577A Expired - Fee Related GB2475645B (en) 2006-06-28 2007-06-26 A field effect transistor

Country Status (1)

Country Link
GB (1) GB2475645B (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6426525B1 (en) * 2001-04-18 2002-07-30 Tyco Electronics Corporation FET structures having symmetric and/or distributed feedforward capacitor connections
US20050047038A1 (en) * 2003-08-27 2005-03-03 Akishige Nakajima Electric component for communication device and semiconductor device for switching transmission and reception
US20050116257A1 (en) * 2003-06-20 2005-06-02 James Oakes Field effect transister structures

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6426525B1 (en) * 2001-04-18 2002-07-30 Tyco Electronics Corporation FET structures having symmetric and/or distributed feedforward capacitor connections
US20050116257A1 (en) * 2003-06-20 2005-06-02 James Oakes Field effect transister structures
US20050047038A1 (en) * 2003-08-27 2005-03-03 Akishige Nakajima Electric component for communication device and semiconductor device for switching transmission and reception

Also Published As

Publication number Publication date
GB2475645B (en) 2011-10-26
GB201103577D0 (en) 2011-04-13

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20190626