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Schematic symbol for the OTA — Like the standard operational amplifier, it has both inverting (−) and noninverting (+) inputs; power supply lines (V+ and V−); and a single output. Unlike the traditional op-amp, it has two additional biasing inputs, IABC and Ibias

The LM13700 (co-invented by Bill Gross and Don Sauer)[1] consists of two current controlled operational transconductance amplifiers (OTA), each having differential inputs and a push-pull output. The LM13700 is like a standard op-amp: each has a pair of differential inputs and a single output, but an OTA is voltage in and current out rather than voltage in and voltage out; and OTAs are programmable via the IABC pin. Linearizing diodes at the input reduce distortion and allow increased input levels. The darlington output buffers provided are specifically designed to complement the wide dynamic range of the OTA. This chip is very useful in audio electronics especially in analog synthesizer circuits like voltage controlled oscillators, voltage controlled filters, and voltage controlled amplifiers. The darlington output buffers on the LM13700 are different from those on the LM13600 in that their bias currents (and hence their output DC levels) are independent of IABC pin. This usually results in performance superior to that of the LM13600 in audio applications.

Darlington pair buffers

Pins 7 and 8 are the inputs to a pair of Darlington pair buffers. These have nowhere as high an input impedance as a JFET input op-amp. When an external op-amp is used instead, the unused buffer pins can safely be left floating.[2][3]

Equivalents and clones

  • NJM13700

See also


This page uses Creative Commons Licensed content from Wikipedia:LM13700 (view authors).

  1. ^ Acknowledgements, Music From Outer Space website
  2. ^ Terminating unused darlington buffer in LM13700?, TI E2E Community Amplifiers Forum
  3. ^ Make: Analog Synthesizers by Ray Wilson, Maker Media, 2013, ISBN 1449345220

Further reading

  • Make: Analog Synthesizers by Ray Wilson, Maker Media, 2013, ISBN 1449345220, Appendix B. The LM13700

External links