Silicon Laboratories Inc.
Accurate peak detector

Abstract:

A peak detector including an input transistor, an isolation transistor, at least one load transistor, a buffer, a control transistor, a current source and at least one resistor. The isolation transistor isolates the input and load transistors from the supply voltage for power supply rejection. The buffer, control transistor, current source and resistor(s) bias the input transistor to remain in a saturation region and each load transistor to remain in a triode region. The buffer may be a unity gain buffer. The control transistor may match each load transistor with matching threshold voltages. An input bias circuit may be included to bias an input node to a direct-current voltage. The load transistor(s) may be biased to have so that the output voltage is proportional to a peak voltage of the input node. The peak detector may be configured to detect multiple inputs and may have shared circuitry.