The LM13700 is an integrated circuit consisting of two current controlled
operational transconductance amplifier
The operational transconductance amplifier (OTA) is an amplifier whose differential input voltage produces an output current. Thus, it is a voltage controlled current source (VCCS). There is usually an additional input for a current to control t ...
s (OTA), each having differential inputs and a push-pull output.
The LM13700 is like a standard
op-amp
An operational amplifier (often op amp or opamp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op amp produces an output potential (relative to c ...
: 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
An analog (or analogue) synthesizer is a synthesizer that uses analog circuits and analog signals to generate sound electronically.
The earliest analog synthesizers in the 1920s and 1930s, such as the Trautonium, were built with a variety of ...
circuits like
voltage controlled oscillator
A microwave (12–18GHz) voltage-controlled oscillator
A voltage-controlled oscillator (VCO) is an electronic oscillator whose oscillation frequency is controlled by a voltage input. The applied input voltage determines the instantaneous oscillat ...
s,
voltage controlled filter
A voltage-controlled filter (VCF) is an electronic filter whose operating characteristics (primarily cutoff frequency) can be set by an input control voltage. Voltage controlled filters are widely used in synthesizers.
A music synthesizer VCF al ...
s, and
voltage controlled amplifier
A variable-gain (VGA) or voltage-controlled amplifier (VCA) is an electronic amplifier that varies its gain depending on a control voltage (often abbreviated CV).
VCAs have many applications, including audio level compression, synthesizers and am ...
s. 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.
See also
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Transconductance Transconductance (for transfer conductance), also infrequently called mutual conductance, is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device. Conductance is the reciproca ...
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Operational amplifier
An operational amplifier (often op amp or opamp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op amp produces an output potential (relative to c ...
*
Transconductance amplifier Transconductance (for transfer conductance), also infrequently called mutual conductance, is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device. Conductance is the reciproc ...
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current mirror
A current mirror is a circuit designed to copy a current through one active device by controlling the current in another active device of a circuit, keeping the output current constant regardless of loading. The current being "copied" can be, and ...
References
External links
A Short Discussion of the Operational Transconductance Amplifier
Linear integrated circuits
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