Efficient Power Booster
Posted on Sep 25, 2012 3198
This power booster functions as a high-efficiency `power multiplexer` or, if you supply an external signal-source,
as a high-power linear amplifier. If you want to drive a load with a high-power square wave, the circuit simply draws power from two external power sources, VI and V2, alternately. In this mode, the circuit"s power-handling devices function as switches, dissipating minimal power. The RC time constant of the integrator, IC1, determines the circuit"s oscillation period. If you supply an external drive waveform, the circuit functions as a linear amplifier, and, consequently, inherently dissipates varying portions of that power. The power amplifier is stable for gains > 15. Diodes D1 and D2 limit the FET"s gate-voltage swing to less than 15 V. D3 is a dual Schottky diode that protects the FETs from short circuits between the two supplies, VI and V2, through a FET"s parasitic diode. With D3 in place, you can choose either power channel for the higher voltage input, lb drive the FETs, Q5 and Q6, at switching frequencies greater than 1 kHz, you will have to use gate drivers for them.