Abstract A tracking level detector is described capable of accommodating n analog inputs, where n is an integer ranging from one to infinity, to provide an analog output equal in magnitude and electrically buffered from one of the n inputs having the largest analog value (or lowest analog value according to the embodiment chosen), as compared to the remaining n - 1 inputs. The level detector is designed to exhibit a high input impedance at the n inputs to avoid loading the inputs and minimize the current drain. Additionally, a high differential and common mode input capability is established by providing a floating bias to the level detecting circuitry. Modified embodiments include an encoder which provides an additional digital coded output corresponding to the one of the n inputs controlling the analog output. Codes of various bit lengths are implementable. The characteristic advantages of the detector are obtained by utilitizing n operational amplifiers having their negative inputs connected in parallel and tied to the analog output at a common node point in parallel with a bias voltage supply.
A tracking detector comprising means for comparing the level of n analog electrical inputs, where n is an integer from one to infinity, and responsive to one of said n inputs having an extreme analog value of predetermined sign at any given point in time as compared to the remaining n - 1 inputs to provide an analog output electrically buffered from and equal to said one input having the extreme value including: n operational amplifiers having a first non-inverting input and a second inverting input and an output, each of said inverting inputs being connected in parallel to said analog output and each of said non-inverting inputs being connected to corresponding ones of said n inputs; n diodes respectively connected in series with corresponding ones of said n operational amplifier outputs in a direction to pass the output in accordance with the predetermined sign, each of said diodes being wire OR-ed to said analog output so as to form a feedback loop between the corresponding inverting inputs and outputs of the respective operational amplifiers; bias reference voltage means connected at said analog output having a predetermined floating voltage value to bias said n operational amplifiers to pass said one of said n inputs having the extreme value to said analog output so as to accommodate high common mode input voltages on said n inputs in the order of magnitude of said bias voltage; and an encoder electrically connected as a part of said feedback loop to said n operational amplifiers and responsive to said one of said n inputs having the extreme analog value to provide a digital coded output corresponding thereto having x bits where 2x equals n.
Claim 2
Dependent Claim
280 words
A tracking detector comprising means for comparing the level of n analog electrical inputs, where n is an integer from one to infinity, and responsive to one of said n inputs having an extreme analog value of predetermined sign at any given point in time as compared to the remaining n - 1 inputs to provide an analog output electrically buffered from and equal to said one input having the extreme value including: n operational amplifiers having a first non-inverting input and a second inverting input and an output, each of said inverting inputs being connected in parallel to said analog output and each of said non-inverting inputs being connected to corresponding ones of said n inputs; n diodes respectively connected in series with corresponding ones of said n operational amplifier outputs in a direction to pass the output in accordance with the predetermined sign, each of said diodes being wire OR-ed to said analog output so as to form a feedback loop between the corresponding inverting inputs and outputs of the respective operational amplifiers; bias reference voltage means connected at said analog output having a predetermined floating voltage value to bias said n operational amplifiers to pass said one of said n inputs having the extreme value to said analog output so as to accommodate high common mode input voltages on said n inputs in the order of magnitude of said bias voltage; and an encoder electrically connected as a part of said feedback loop to said n operational amplifiers and responsive to said one of said n inputs having the extreme analog value to provide a digital coded output corresponding thereto having x bits where 2x equals n.