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*Every week I add here a little story about an existing circuit contradiction. I number and date these ideas consecutively as they have appeared in my mind; then, I arrange the contradictions systematically of circuit evolution - passive > transistor > op-amp etc.*

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Number/Week | Circuit | Circuit Contradictions |
---|---|---|

Contradictions in Passive Circuits | ||

Contradiction 1 September 27, 2004 |
Current-to-Voltage Converter | The resistor in the circuit of a current-to-voltage converter has to have low resistance because of the input stage and it has to have high resistance because of the next stage. How do we solve the contradiction? Does it exist in case when the input stage is a constant current source? |

Contradiction 2 October 04, 2004 |
Resistance-to-Voltage Converter | The resistor in the circuit of a resistance-to-voltage converter has to have low resistance because of the input stage and it has to have high resistance because of the next stage. How do we solve the contradiction? Does it exist in case when the input stage is a constant current source? |

Contradiction 3 October 11, 2004 |
Current-to-Voltage Capacitive Integrator | The voltage drop across the capacitor in the circuit of a has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve the contradiction? Does it exist in case when the input stage is a constant current source? current-to-voltage capacitive integrator |

Contradiction 4 October 18, 2004 |
Current-to-Voltage Inductive Differentiator | The voltage drop across the inductor in the circuit of a |

Contradiction 5 October 25, 2004 |
Current-to-Voltage Logarithmic Converter | The voltage drop across the diode in the circuit of a |

Contradiction 6 November 01, 2004 |
R2/R1 Voltage Divider | Imagine, we have to build a "perfect" voltage divider with ratio k = R2/R1 instead the "ordinary" voltage divider with a ratio k = R2/(R1+R2). For this purpose, we cascade an input |

Contradiction 7 November 08, 2004 |
Voltage-to-Voltage Capacitive Differentiator | In order to build a |

Contradiction 8 November 15, 2004 |
Voltage-to-Voltage Capacitive Integrator | The voltage drop across the capacitor in the circuit of a voltage-to-voltage capacitive integrator has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve this contradiction? |

Contradiction 9 November 22, 2004 |
Voltage-to-Voltage Inductive Differentiator | The voltage drop across the inductor in the circuit of a |

Contradiction 10 November 29, 2004 |
Voltage-to-Voltage Inductive Integrator | The voltage drop across the resistor in the circuit of a voltage-to-voltage inductive integrator has to be low enough because of the input stage and it has to be high enough because of the next stage. How do we solve this contradiction? |

Contradiction 11 December 06, 2004 |
Voltage-to-Voltage Logarithmic Converter | The voltage drop across the diode in the circuit of a |

Contradiction 12 December 13, 2004 |
Voltage-to-Voltage Antilogarithmic Converter | The voltage drop across the resistor in the circuit of a |

Contradiction 13 December 20, 2004 |
Ammeter | A movement coil has to have few winding in order to be low resistive (not to disturb the current measured) and it has to have many winding in order to be high sensitive. How do we solve the contradiction? |

Contradictions in Transistor Circuits | ||

Contradiction 14 December 27, 2004 |
Base Resistor | The base resistor in the circuit of a transistor switch has to have high resistance in order to obtain high input resistance; at the same time, the base resistor has to have low resistance in order to saturate the transistor. How do we solve the contradiction? |

Contradiction 15 January 03, 2005 |
Collector Resistor | The collector resistor in the circuit of a transistor switch has to have high resistance in order to saturate the transistor; at the same time, the collector resistor has to have low resistance in order to keep the high output level. How do we solve the contradiction? |

Contradiction 16 January 10, 2005 |
Collector Resistor (Transistor Amplifier) | The collector resistor in the circuit of a common-emitter amplifier has to have high resistance in order to obtain high amplification; at the same time, the collector resistor has to have low resistance in order to drive a big load enough. How do we solve the contradiction? |

Contradiction 17 January 17, 2005 |
Emitter Resistor (DifferentialTransistor Amplifier) | The emitter resistor in the circuit of a transistor differential amplifier has to have high resistance in order to obtain high CMRR; at the same time, it has to have low resistance in order to provide collector currents enough. How do we solve the contradiction? |

Contradiction 20 February 07, 2005 |
Emitter Resistor in Transistor Current Source | The emitter resistor in the circuit of a transistor current source has to have high resistance in order to obtain low error; at the same time, it has to have low resistance in order to provide high voltage compliance. |

Contradiction 18 January 24, 2005 |
Bias Voltage Divider | The bias voltage divider in the circuit of a common-emitter amplifier has to have high resistance in order not to load the input source; at the same time, it has to have low resistance in order to provide the base current needed. How do we solve the contradiction? |

Contradiction 19 January 31, 2005 |
Blocking Capacitors | The blocking capacitors in an AC amplifier has to be large enough in order to pass the AC current; at the same time, they have to be small enough in order not to "block" the amplifier. How do we solve the contradiction? |

Contradictions in Op-amp Circuits | ||

February 14, 2005 |
Input Resistor (R1) in Op-Amp Inverting Amplifier | The input resistor R1 in the circuit of an op-amp inverting amplifier has to have high resistance in order not to disturb the input voltage source; at the same time, it has to have low resistance in order to obtain high gain. How do we solve the contradiction? |

Contradiction 22 February 21, 2005 |
Output Resistor (R2) in Op-Amp Inverting Amplifier | The output resistor R2 in the circuit of an op-amp inverting amplifier has to have extremely high resistance in order to obtain very high gain; at the same time, it has to have reasonable resistance. How do we solve the contradiction? |

Contradiction 23 February 28, 2005 |
Leakage Input Resistor in Op-Amp Non-Inverting Amplifier | The leakage input resistor in the circuit of an op-amp non-inverting amplifier has to have high resistance in order not to disturb the input voltage source; at the same time, it has to have low resistance in order to eliminate the influence of the op-amp input currents. How do we solve this contradiction? |

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*Last updated
February 27, 2005
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