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Cell Independent Feedback Stabilization for Analog Potentiostat

IP.com Disclosure Number: IPCOM000086787D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Galwey, RTK: AUTHOR [+2]

Abstract

A stabilizing network is used with an analog potentiostat so that the potentiostat's feedback stability is relatively insensitive to the cell transfer function. At the same time the closed-loop bandwidth of the system is maintained.

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Cell Independent Feedback Stabilization for Analog Potentiostat

A stabilizing network is used with an analog potentiostat so that the potentiostat's feedback stability is relatively insensitive to the cell transfer function. At the same time the closed-loop bandwidth of the system is maintained.

The schematic for the potentiostat is shown in Fig. 1. Only a portion of the potentiostat feedback loop transfer characteristics is tailored to provide cell- independent stability for the total loop. This is accomplished by the use of two specific requirements. First, the initial roll-off frequency of buffer amplifier A1 in the unity-gain configuration is tailored to be several orders of magnitude above the roll-off frequency of driver amplifier A2. The separation required is about one-twentieth of the DC gain (in db) of A1 and A2. This insures that the open loop gain has dropped below unity before the phase lag appreciably exceeds 90 degrees. Second, the stabilizing network B must introduce a phase lead in the frequency spectrum intermediate the A1 and A2 frequencies such that the net phase lag, when the gain magnitude has dropped to unity, is decidedly less than 90 degrees.

An example of the stabilizing network B is shown in Fig. 2.

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