High Input Impedance Source Follower
Category: Basic Circuits
Designer: RANA MUHAMMAD ADNAN KHALIL
Notes
A simple voltage source follower can be implemented with an EPAD MOSFET connected as a source follower where the o/p currents are supplied by drain to source current. This circuit is analogous to the classic emitter follower using a bipolar transistor. In this case the i/p (source) voltage and its source impedance are completely isolated from the o/p voltage and o/p currents due to the extremely high i/p impedace of the MOSFET. The impedance transformed Vout and Iout are dependent only on the i/p voltage and the o/p impedance of the EPAD MOSFET. An o/p resistor is connected to ground or other reference voltages will produce a buffered o/p voltage that follows the i/p voltage very closely. Recommended ICs for Enhancement mode EPAD MOSFET are ALD110800, ALD110802, ALD110804 and for depletion mode EPAD MOSFET are ALD114804, ALD1148013, ALD114835.