Emitter follower type sepp circuit

Claim 2

1 An emitter-follower type SEPP circuit comprising: first and second amplifying elements connected in an emitter-follower and class B SEPP arrangement; first and second error amplifiers provided respectively for said first and second amplifying elements, each 5 error amplifier having at least three input terminals one noninverting input terminal of which is connected to a circuit input terminal; first and second current generating means connected respectively between an output of said first error amplifier and an input terminal of said first amplifying element and between an output of said second error amplifier and an input terminal of said second amplifying element for producing a current; and 10 a resistance network connected between a circuit output terminal and outputterminals of said first and second amplifying elements, said resistance network having first and second idle current detecting terminals for detecting idle currents of said first and second amplifying elements, respectively, and a signal detecting terminal for detecting a signal output current, said first error amplifier amplifying an error voltage between a voltage at said first idle current detecting 15 terminal and a voltage which provided by level-shifting a voltage at said circuit inputterminal by a predetermined value, said second error amplifier amplifying an error voltage between a voltage at said second idle current detecting terminal and a voltage which provided by level-shifting a voltage at said circuit input terminal by a predetermined value, and 20 at least one input terminal of each of said first and second error amplifiers being connected to said signal detecting terminal of said resistance network, wherein when said first error amplifier operates in response to an error voltage between a voltage at said first idle current detecting terminal and a voltage provided by level- shifting a voltage at said circuit input terminal, said second error amplifier operates in response to an error voltage between a voltage at said 25 second idle current detecting terminal and a voltage which is provided by level-shifting a voltage at said signal detecting terminal, and when said second error amplifier operates in response to an error voltage between a voltage at said second idle current detecting terminal and a voltage provided by level- shifting a voltage at said circuit input terminal, said first error amplifier operates in response to an error voltage between a voltage at said first idle 30 current detecting terminal and a voltage which is provided by level- shifting a voltage at said signal detecting terminal.

Claim 3

2 The emitter-followertype SEPP circuit of claim 1, wherein said one noninverting inputterminal is connected directly to said circuit input terminal.

Claim 4

3 The emitter-follow type SEPP circuit of claim 1, further comprising level shifting means connected 35 between said one noninverting inputterminal and said circuit inputterminal.

Claim 5

4 An emitter-follower type SEPP circuit comprising: first and second error amplifiers, each of said first and second error amplifiers having noninverting first and second inputterminals and an inverting third inputterminal; first and second constant current sources having respective firstterminals coupled to outputs of said first 40 and second error amplifiers; a bipolar NPN transistor having a base coupled to a second terminal of said first constant current source, a collector coupled to a positive power supply terminal, and an emitter coupled to said third input of said first error amplifer; a bipolar PNP transistor having a base coupled to a second terminal of said second constant current 45 source, a collector coupled to a negative power supply terminal, and an emitter coupled to said third input of said second amplifier; firstthrough fourth bias potential sources, said first bias potential source having a negativeterminal coupled to a signal input terminal and a positive terminal coupled to said first inputterminal of said first amplifier, said second bias potential source having a positive terminal coupled to said signal input terminal 50 and a negative terminal coupled to said first input terminal of said second amplifier, said third bias potential source having a positive terminal coupled to said second input terminal of said first amplifier, and said fourth bias potential source having a negative terminal coupled to said second input terminal of said second error amplifier and a positive terminal coupled to a negative terminal of said third bias potential source; and resistance network means coupled between said emitters of said bipolar transistors and an output 55 terminal, said resistance network means having a feedback terminal coupled to said negative terminal of said third bias potential source and said positive terminal of said fourth bias potential source. The emitter-follower type SEPP circuit of claim 4, wherein said resistance network means comprises a first resistor having a firstterminal coupled to said emitter of said first bipolartransistor, a second resistor having a first terminal coupled to said emitter of said second bipolartransistor and a second terminal 60 coupled to a second terminal of said first resistor, a third resistor coupled between said second terminals of said first and second resistors and an output terminal, and voltage dividing means coupled across said third resistor for feeding back to said negative terminal of said third bias potential source and said positive terminal of said fourth bias potential source a predetermined proportion of a potential developed across said 65third resistor 65 GB 2139031 A

Claim 6

5

Claim 7

5

Claim 8

6 The emitter-follower type SEPP circuit of claim 5, wherein said voltage dividing means comprises a variable resistor.

Claim 9

7 The emitter-followertype SEPP circuit of claim 4, wherein said resistance network means comprises a delta-connected resistor circuit connected in parallel with a wye- connected resistor circuit, one terminal of the parallel connected circuits being coupled to said emitter of said first bipolartransistor, a second terminal 5 of said parallel connected circuits being coupled to said emitter of said second bipolar transistor, and a third terminal of said parallel connected circuits being coupled to an output terminal, a resistor Qf said wye-connected resistor circuit being a variable resistor and having a variable tap terminal coupled to said negative terminal of said third bias potential source and said positive terminal of said fourth bias potential source 10

Claim 10

8 The emitter-follower type SEPP circuit of claim 4, wherein said resistance network means comprises a bridge circuit and a variable resistor connected in parallel with a center resistor of said bridge circuit, a variable tap terminal of said variable resistor being coupled to said negative terminal of said third bias potential source and said positive terminal of said fourth bias potential source.

Claim 11

9 Anemitter-followertype SEPP circuitsubstantiallyasdescribedwithreferencetoanyof Figures 4 to 15 of the accompanying drawings. Printed in the UK for HMSO, D 8818935, 9/84, 7102. Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

Claim 12

9 Anemitter-followertype SEPP circuitsubstantiallyasdescribedwithreferencetoanyof Figures 4 to 15 of the accompanying drawings. Printed in the UK for HMSO, D 8818935, 9/84, 7102. Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.