Negative capacitance amplifier You are trying to measure axo

Negative capacitance amplifier You are trying to measure axon potentials with a micropipette and reference electrodes. The micropipette has a tip resistance of 500 M Ohm and shunt capacitance of 3 to 8 pF. You expect to see signals with approximately 100mV amplitude. Design an amplifier to measure the signal from DC to 10 kHz. Compensate for the shunt capacitance using a negative capacitance amplifier. The ADC has plusminus 12V inputs.

Solution

Capacitance is the ability to store electrical energy. Almost all things, including you, can store some electrical energy and therefore have capacitance. When you rub your feet across a carpet, charged particles called electrons can be transferred from the carpet to you. When positive and negative charges are separated, the stored electrical energy increases. The charges you have picked up from the carpet give you electrical energy that you store until you touch something like a metal doorknob or another person that allows the energy to be released. You feel this as a mild shock as the energy leaves your body.

Capacitors

Although the ability to store some electrical energy is common, devices called capacitors are purposely designed to store large amounts of electrical energy. A typical capacitor consists of two conducting surfaces (usually metal plates) separated by an insulating material like air, rubber, or paper. This insulating material is called a dielectric.