Temperature compensated wide dynamic range linear envelope detector

Claim 1

An amplitude modulation detection apparatus, comprising: first means to receive amplitude modulated carrier frequency signals, an envelope detection means including a first and second diode rectifier commonly connected at their cathodes to provide a replica of the amplitude modulation of the carrier frequency signal, a transformer coupling the first means to the detection means, a low-pass video filter to suppress unwanted frequency components, second means connecting the commonly connected cathodes to the video filter at its input including a first resistance means (59, 60, 61) to minimize impedance mismatch between the detection means and the video filter, and a forward biasing means including a DC voltage source connected to an operational amplifier at its input with its output thereof connected to the coupling transformer to forward bias the pair of diodes, said forward biasing means including a third diode rectifier connected at its anode to the operational amplifier input and at its cathode to a second resistance means (71) to vary the voltage input to the operational amplifier as a function of temperature, said second resistance means having a value governed by the value of the first resistance means to subject the first, second, and third diode rectifiers to the same operating conditions.