We have designed and implemented a few compact discrete-time chaos generator circuits, for example a chaotic oscillator using "three-transistor" nonlinear map:
Bifurcation diagram of the above circuit.
More information about this and other circuits can be found in the following papers:
V.D.Juncu, M.Rafiei-Naeini and P.Dudek , "Integrated circuit implementation of a compact discrete-time chaos generator", Analogue Integrated Circuits and Signal Processing, Vol.46, Issue 3, pp. 275-280, March 2006
P.Dudek and V.D.Juncu, "An area and power efficient discrete-time chaos generator circuit", European Conference on Circuit Theory and Design, ECCTD'05, Cork, Ireland, 29 Aug - 1 Sept 2005
P.Dudek and V.D.Juncu, "Compact Discrete-Time Chaos Generator Circuit", Electronics Letters, Vol.39, No. 20, pp. 1431-1432, October 2003