公开(公告)号：DE69413235T2

公开(公告)日：1999-01-28

申请号：DE69413235

申请日：1994-10-31

Applicant: ST MICROELECTRONICS SRL

Inventor： BOTTI EDOARDO ,  MANDRINI TIOZIANA

IPC: H03F3/68 ,  H03F3/30 ,  H03F3/45 ,  H03F3/50 ,  H03F3/72

Abstract: A circuit assembly comprising an operational amplifier having an input stage (20) coupled directly to an output stage (21) in the form of a class AB amplifier is described. A compensating capacitance (Cc) is connected between a first input (IN1) and the output (OUT) of the output stage (21). A conventional feedback system (Rf1, Rf2) is provided between the output (OUT) of the output stage and an input of the input stage (20). Three switches (S1, S2, S3) enable the operational amplifier to be switched into three configurations: one in which it behaves in the manner of a conventional operational amplifier; one in which it behaves in the manner of a buffer; and one in which it has high impedance between its output terminals (OUT, earth). The class AB amplifier is constructed such that its final transistors (Qpf, Qnf) are controlled continuously and such that its polarisation circuits are substantially independent of those which provide current to the load (Zo), such that switching from one configuration to the other occurs without transients being generated.

公开(公告)号：DE69413235D1

公开(公告)日：1998-10-15

申请号：DE69413235

申请日：1994-10-31

Applicant: ST MICROELECTRONICS SRL

Inventor： BOTTI EDOARDO ,  MANDRINI TIOZIANA

IPC: H03F3/68 ,  H03F3/30 ,  H03F3/45 ,  H03F3/50 ,  H03F3/72

Abstract: A circuit assembly comprising an operational amplifier having an input stage (20) coupled directly to an output stage (21) in the form of a class AB amplifier is described. A compensating capacitance (Cc) is connected between a first input (IN1) and the output (OUT) of the output stage (21). A conventional feedback system (Rf1, Rf2) is provided between the output (OUT) of the output stage and an input of the input stage (20). Three switches (S1, S2, S3) enable the operational amplifier to be switched into three configurations: one in which it behaves in the manner of a conventional operational amplifier; one in which it behaves in the manner of a buffer; and one in which it has high impedance between its output terminals (OUT, earth). The class AB amplifier is constructed such that its final transistors (Qpf, Qnf) are controlled continuously and such that its polarisation circuits are substantially independent of those which provide current to the load (Zo), such that switching from one configuration to the other occurs without transients being generated.