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Class Exercise 9 (May 17 - 22, 2004)

9. Op-amp Converters with Parallel Negative Feedback    Op-amp Integrator Builder

So far, we have managed to derive, build and even "invent" a total of 68 circuit building blocks. Here, we will improve almost all passive circuits we have discussed on the first (1, 2, 3, 4, 5) converting them into almost ideal circuits with parallel negative feedback and putting them in the library ; thus it will grow with new 22 circuit building blocks reaching up to 90 basic circuits:

Op-amp Resistive Circuits with Current Output
voltage-to-current converter resistance-to-current converter
voltage controlled current source resistance controlled current source
voltage/resistance divider

Op-amp Resistive Circuits with Voltage Output
current-to-voltage converter resistance-to-voltage converter
current x resistance multiplier

Op-amp Compound Circuits with Voltage Input and Output
inverting voltage divider inverting voltage summer

Op-amp Reactive Circuits with Voltage/Current Output
KINDS integrators  differentiators 
I output L integrator V > I C differentiator V > I
V output C integrator I > V L differentiator I > V

Op-amp Reactive Circuits with Voltage Input and Output
KINDS integrators differentiators
capacitive  RC integrator V > V RL differentiator V > V
inductive  LR integrator V > V RL differentiator V > V

Op-amp Diode Circuits with Voltage Input and Output
limiters  parallel series
functional logarithmators antilogarithmators

9.1. Converting passive circuits into active ones (a universal principle). Deriving the idea of removing disturbance by antidisturbance from many situations of our life. Concretizing into a principle of removing voltage by antivoltage (parallel negative feedback).

9.1.1. Converting resistive passive circuits into op-amp circuits.
9.1.1.1. Op-amp converters with current output: voltage-to-current converter, resistance-to-current converter and voltage-into-resistance divider. Keeping a constant current by supplementing the input voltage in order to compensate the losses in the load (method 3). Future application in ramp generators.

Example 1: How to make a current source?

??????: ?? ?? ???????????? ???????? ? ??????, ??????????? ??????? ???????? ? ???????????? ???????? ?? ?????????? ? ???? ?????????? ???? ??????? ???????? ?? ???.

????????????: ????????????? ????????? ?????????? ???????? ????? ??????????? A ???? ?????? ??????? ??????????, ??????? ?? ???? ????? ????.


Example 2: How to make an ideal ammeter?

??????: ?? ?? ???????????? ???????? ? ???????????, ??????????? ??????? ???????? ? ???????????? ???????? ?? ?????????? ? ???? ?????????? ???? ??????? ??????????.

????????????: ????????????? ????????? ?????????? ???????? ????? ??????????? A ???? ?????? ??????? ??????????, ??????? ?? ???? ????? ????.

 

9.1.1.2. Op-amp converters with voltage output: current-to-voltage converter, resistance-to-voltage converter and voltage-into-resistance divider.
9.1.1.3. Compound converters with voltage inputs/output: inverting voltage divider (inverting amplifier); inverting voltage summer.
The idea.
????????????? ????????? ?????????? ???????? ????? ???????????? C ???? ?????? ??????? ??????????, ??????? ?? ???? ????? ????.
The implementation.
Botomless vessel

9.1.2. Converting reactive passive circuits into op-amp circuits.
9.1.2.1. Capacitive circuits: integrators; differentiators. Application 1: ramp generation. Building ramp generator from an external square generator and an op-amp RC integrator.
9.1.2.2. Inductive circuits: integrators; differentiators.

9.1.3. Converting imperfect diode circuits into op-amp circuits: parallel diode limiter (an ideal diode), logarithmic and antilogarithmic converter.

9.2. Virtually decreasing a resistance and increasing a capacitance by parallel NFB. "Bottomless" capacitor (another view point at op-amp RC integrator).

9.3. Transforming NFB op-amp circuits into negative impedance circuits. Applications: negative impedance converters (NIC).

Last updated October 22, 2004

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