(19)
(11) EP 1 378 992 A8

(12) CORRECTED EUROPEAN PATENT APPLICATION

(48) Corrigendum issued on:
10.03.2004 Bulletin 2004/11

(43) Date of publication:
07.01.2004 Bulletin 2004/02

(21) Application number: 03012147.9

(22) Date of filing: 02.06.2003
(51) International Patent Classification (IPC)7: H03F 3/50
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR
Designated Extension States:
AL LT LV MK

(30) Priority: 01.07.2002 DE 10229460

(71) Applicant: TEXAS INSTRUMENTS DEUTSCHLAND GMBH
85356 Freising (DE)

(72) Inventors:
  • Prexl, Franz
    85445 Oberding (DE)
  • Steinhagen, Wolfgang, Dr.
    85419 Mauern (DE)
  • Oberhuber Ralph, Dr.
    84036 Kumhausen (DE)

(74) Representative: Degwert, Hartmut, Dipl.-Phys. 
Prinz & Partner GbR, Manzingerweg 7
81241 München
81241 München (DE)

   


(54) Voltage follower


(57) The invention relates to a voltage follower. The voltage follower in accordance with the invention comprises a first field-effect transistor (MN1) whose gate forms the input of the voltage follower. Further provided is a second field-effect transistor (MN2) whose drain connected to the gate forms the output of the voltage follower. The sources of the two field-effect transistors (MN1, MN2) are connected to each other and to the drain of a third field-effect transistor (MN3) serving as current source and to the gate of which a predefined bias voltage is applied. The invention employs in addition a fourth field-effect transistor (MN4) whose source-drain path is circuited between the output of the voltage follower and the drain of the third field-effect transistor (MN3) and whose gate is connected to the gate of the third field-effect transistor (MN3). As compared to prior art voltage followers the voltage follower in accordance with the invention comprises a wider voltage range in which it can be put to use. This can be made use of e.g. in amplitude shift-keyed (ASK) demodulators incorporating the voltage follower in accordance with the invention and which need to be operated with particularly small supply voltages.