DESIGN PHASE: measurement
SUB ELEMENT NAME: transfer function measurements
VARIABLE NAME: [HEMX]
DATE: REVISION LETTER: REVISION DATE:
APPLICABILITY: feedback circuits, regulator circuits, and
filter circuits.
ACTIVITY: Measure transfer functions (frequency plots) including
open loop input impedance, input impedance, output impedance, and
audiosusceptibility. Special equipment is usually needed
(Venable, Ridley, EMI meters, etc.)
OUTPUT: Measurements and plots in laboratory notebook for later
comparison to specifications and analysis.
ALGORITHM:
[HEMX] = engineer hours for transfer function measurements
[HTMX] = technician hours for transfer function measurements
0.0+ set up time
0.0* time per transfer function measurement
[NX] number of transfer function measurements
[NX] = [INPUT COUNT]+[OUTPUT COUNT]+[INPUT COUNT]*[OUTPUT COUNT]
DISCUSSION:
The [NX] algorithm should be improved by defining desired
transfer functions for for each type of circuit.
For a single input, single output circuit, such as a filter or
regulator, the desired transfer functions are input impedance,
output impedance, and input-to-output transfer (attenuation or
audiosusceptibility) and algorithm gives correct answer of three.
For a two input, single output regulator the desired transfer
functions are two input to output transfer functions, and the
algorithm gives the correct transfer function.
However, for a switching mode power supply with one input and one
output, the reference below gives 12 open loop transfer functions
and 8 closed loop transfer functions that may be of interest to the
circuit designer.
Original: Foutz, J., Power Supply Circuit Development Estimating Aid - An Expert System Application, IEEE Applied Power Electronics Conference Record, New Orleans, February 1-5, 1988. Revised 21 February 2001
Copyright © 2001 Jerrold Foutz
All Rights Reserved