Designing a High-Precision AC Current Source to Measure the nm-Scale Displacements in Mechanical Systems

Table 1

Performances of the source IQOA.

f = 100 kHz,V1 − V2 = 500 mV					Zprobe,max = 2 MΩ
	Rprobe = 100 kΩ		Rprobe = 600 kΩ
Op amp	TL081	OP249	OPA657	OPA655
	± 15	± 15	± 5	± 5
	7.5	7.5	2.5	2.5
	7.191	7.7	2.332	2.337
	7.9	8.6	4.5	4.476
	0.078	0.078	1020	144
	1.333	1.56	3.51	47.4
	1.335	1.568	1020	151.26
(analytical model)	19.7	18.4	0.028	0.14
(PSPICE)	24	20.5	0.04	0.11