Origins of the Baxandall Super Pair?

[jez]

There seems to virtually no information available on the origins, theory and applications of the Baxandall super pair....
A Google search brings up very little other than references to a couple of threads on this very site (which discuss only stability issues) and I can find nothing to attribute the circuit to Peter Baxandall. It's almost as if someone on DIY audio has plucked the circuit out of thin air!?
The idea seems to be shrouded in mystery! Maybe someone on this site can shine a little light on the subject?

[teemuk]

Maybe this sheds some light, maybe not...

Baxandall Super Pair

[jez]

I had already seen this post but had not followed it to the end. It seemed to be only about stability issues so I lost interest.....
There are some partial answers there anyway. if I can access the referenced articles anyway!

[jez]

Well it would seem that the references by Walt are, in the main, only accessible to those who are payed up members of the IEEE.....
Oh well.

[Elvee]

Originally Posted by jez

Well it would seem that the references by Walt are, in the main, only accessible to those who are payed up members of the IEEE.....
Oh well.

Pease has written something about it; if I remember correctly, the Baxandall in question is not Peter Baxandall.
In some old french books, this circuit is known as "répéteur".

[jcx]

in "Active Filters for Integrated Circuits" W.E.Heinlein and W. H. Holmes, 1974 the circuit is called a "Super Pair"

since the ref in Heinlein was to Baxandall it seemed obvious to call it Baxandall Super Pair

but Walt's excellent reference list seems to give priority to Larson?

Originally Posted by WaltJ

Some References Related to the Larson, Baxandall / Swallow, and Thompson Constant Current Circuits:

In an earlier post to this “Baxandall Super Pair” thread, I offered a list of references. The updated list below expands on this with several key items. Some comments on the first few of these follow, and these will greatly help in understanding this clever circuit..

In #1, Larson provides an analysis on the use of a composite PNP/NPN complementary pair as a functional high-gain NPN, with two such pairs operated differentially. The impedance characteristics of the output stage device is seen to be improved by a factor of b, the gain of the driving transistor.

In #2, Baxandall and Swallow discuss a (single) current source stage of the PNP/NPN type, having similar improvements with regard to output impedance.

In #3, Jim Thompson describes an op amp with a Figure 6 NPN/PNP current source, designed to overcome the PNP IC transistor b limitations. This NPN/PNP configuration is a functional complement akin to ½ the Larson and to the Baxandall-Swallow setups. It was to be used many times over in other Motorola ICs of the period, in addition to discrete examples within applications.

In #4, Jim Solomon offers a detailed analysis on the use of a composite complementary NPN/PNP pair ala Thompson (above), as a functional high-gain PNP pair, within the front end of what became the MC1556 IC op amp.

In #5, Tom Frederiksen describes use of the Thompson composite complementary pair within a high powered voltage regulator IC.

In #6 the Thompson composite complementary pair is used in Figures 9 and 10 as a current mirror employing 2N3904/3906 discrete transistors. In #7 the Thompson composite complementary pair is used in Figures 3 and 4 as a current mirror employing 2N3904/3906 discrete transistors.

In #8, Maurice Free describes the MC1595 multiplier design, which uses externally the Thompson current source scheme, within an output stage current mirror (Figs. 3 and 4).

My thanks to Jim Thompson for help with his MSEE thesis (#3), and to Maurice Free for help with his MSEE thesis (#8). Thanks also to an anonymous friend for providing the Larson reference, and to Ben Duncan and Morgan Jones, who also provided several references and other background information. Bob Pease has also related his independent development of this type of circuit, in #15 and 17.

Walt Jung
Rev L 032509


1. L. L. Larson, “Differential Amplifier Having Common Base Output Stage of Very High Impedance”, US Patent 3,394,316, filed Jan 29, 1965, issued July 23, 1968.

2. P. J. Baxandall, E.W. Swallow, “Constant Current Source With Unusually High Internal Resistance And Good Temperature Stability,” Electronic Letters, Sept. 1966, Vol. 2, No. 9, pp. 351-352.

3. James Elbert Thompson, “A High Performance Operational Amplifier Utilizing Field Effect Input Devices Compatible With Integrated Circuit Fabrication Techniques”, MSEE Thesis, Arizona State University, June, 1968. See also http://analog-innovations.com/MS_The...mpson_1968.pdf

4. J. E. Solomon, “Lateral PNP-NPN Composite Monolithic Differential Amplifier”, US Patent 3,538,449, filed Nov 22, 1968, issued Nov 3, 1970.

5. Thomas M. Frederiksen, “A Monolithic High-Power Series Voltage Regulator,” IEEE Journal of Solid-State Circuits, Dec 1968, Vol. 3, #4, pp. 380–387.

6. Ed Renschler, “Analysis and Basic Operation of the MC1595,” Motorola Semiconductor Products, Multiplier Series Part I, Application Note AN489, September 1969.

7. Brent Welling and Loren Kinsey, “Using the MC1495 Multiplier in Arithmetic Operations,” Motorola Semiconductor Products, Multiplier Series Part II, Application Note AN490, September 1969.

8. Maurice George Free, “An Integrated Linear-Transconductance Analog Multiplier”, MSEE Thesis, University of Arizona, 1970. See also “An Integrated Linear-Transconductance Analog Multiplier”, Simulation, Vol. 13, #5, November 1969, pp. 243-251.

9. “MC1594L/MC1494L Data Sheet, Figure 15,” Motorola Semiconductor Products, October 1970.

10. Allan Grebene, section 4-5, pp. 133-136, 143-144, within Analog IC Circuit Design, Van Nostrand Reinhold, 1972, ISBN 0-442-22827-9.

11. Hans R. Camenzind, ‘Voltage-to-Current Converter’ section, pp. 266-269, within Chapter 16 ‘Linear Elements, Circuits, and Subsystems’ of Electronic Integrated Systems Design, Van Nostrand Reinhold, 1972.

12. R.C. Jaeger, “A High Output Resistance Current Source,” IEEE Journal of Solid-State Circuits, Aug 1974, Vol. 9, # 4, pp. 192–194.

13. B. Hart, “Homage To Baxandall,” Electronics World (Letters), Jan. 2003, pp. 41.

14. N. Terzopoulos, K. Hayatleh, B. Hart, F. J. Lidgey and C. McLeod, “A Novel Bipolar-Drive Circuit for Medical Applications,” Physiological Measurement Journal, Issue 5, N21-N27, October 2005.

15. Bob Pease, “What's All This PNP Stuff, Anyhow?,” Electronic Design, Sept. 11, 2008, pp. 80. See also http://electronicdesign.com/Articles...605/19605.html

16. Dimitri Danyuk, “On the Optimization of Enhanced Cascode,” Preprint #7571, Presented at the 125th AES Convention, October 2–5, 2008 San Francisco, CA, USA.

17. Bob Pease, “Mailbag; letters from Walt Jung and James E. Thompson”, Electronic Design, October 23, 2008, pp. 72. See also http://electronicdesign.com/Articles...rticleID=19868

[jez]

I don't suppose anyone has a copy of:

Baxandall P.J., and Swallow E.W., ‘Constant current source with unusually high internal resistance and good temperature stability’, Electronic Letters, 1966, Vol. 2 , No 9, pp 351-352.

and would be willing to PM me with it?

Jez.

[AndrewT]

I see fig2 in Pease shows a 22r as base stopper for the second transistor, rather than a high value base stopper for the first transistor.

[homemodder]

Hi jez, I have copies of the follow up on this artical , you may want to have a look at, It does look like P J Baxandall was the first user of this transistor combination.

[jez]

Hi Homemodder,
That would be great, please PM me.
Thanks.