Peak detector circuit

DETAILED DESCRIPTION What is claimed is: 1.
A peak detector circuit for detecting the maximum excursion of an amplitude varying signal, comprising: a network including a capacitor and a charging impedance serially coupled and having a time constant suitable for responding to the maximum excursion of an amplitude varying signal; semiconductor means having an input terminal for receiving said amplitude varying signal and an output terminal coupled to said charging impedance for charging said capacitor toward the maximum excursion of said amplitude varying signal, said means exhibiting an impedance which is subject to increase with a decrease in current drawn therethrough; and a controllable current sink responsive to the amplitude varying signal at the input terminal of said semiconductor means and coupled to the output terminal of said semiconductor means for drawing a component of current through said semiconductor means during the charging of said capacitor which is supplemental to the capacitor charging current drawn therethrough, said supplemental current component being of sufficient magnitude to preclude increase of the impedance exhibited by said semiconductor means during the charging of said capacitor beyond a value which is substantially less than said charging impedance.
2.
A peak detecting sample and hold circuit for detecting the maximum excursion of an amplitude varying signal, comprising: a network including a capacitor serially coupled to a charging impedance and having a time constant suitable for responding to the maximum excursion of an amplitude varying signal; semiconductor means having an input terminal for receiving said amplitude varying signal and an output terminal coupled to said charging impedance for charging said capacitor toward the maximum excursion of said amplitude varying signal; and a controllable current sink responsive to the amplitude varying signal at the input terminal of said semiconductor means and coupled to the output terminal of said semiconductor means for drawing a component of current through said semiconductor means during the charging of said capacitor which is supplemental to the capacitor charging current drawn therethrough and drawing no current when said semiconductor means is not charging said capacitor