Download Worst Case Analysis

Analog Design for Production
Passive Components
Critical Factors:
1.
Ambient Temperature
2.
Thermal Deratings & variation of Primary Parameter
3.
Maximum Imposed Voltage and/or Current
4.
Maximum Imposed dV/dT and/or Frequency
5.
Inductive Frequency (high frequency model)
Minimum Analysis:
•
Component Primary Parameter Tolerances (R, L, C %)
•
Total Power Dissipation vs Package Dissipation (1,2,3,4,5)
•
Composition (1-6), Specific die-electric, construction, etc
Analog Design for Production
Small Signal Amplifiers
Critical Factors:
1.
Component Tolerances, particularly gain setting R’s
2.
OpAmp Input Offset Voltage (Vio), worse for high gain
3.
Input Bias Current (Ib), Input Offset Current (Iio)
4.
Finite Diff Gain (Ad) & Variation of Ad with Frequency
5.
Output Slew Rate and Output Vp-p at Maximum Frequency
Worst Case Analysis:
• Total DC Offset error in Volts (1,2,3)
• Total Gain Error vs Nominal, Converted to Volts (1,4)
• Power Bandwidth for Application (1,5)
Analog Design for Production
Filters
Critical Factors:
1.
Passive Component Tolerances
2.
OpAmp Input Offset Voltage (Vio), worse for high gain
3.
Input Bias Current (Ib), Input Offset Current (Iio)
4.
Loading effects of input source, output loads
5. Output Slew Rate and Output Vp-p at Maximum Frequency
Worst Case Analysis:
• Transfer Function Analysis
• Total DC Offset error in Volts (1,2,3)
• Mag (dB) & Phase (deg) vs Frequency Plots (1,4)
• Power Bandwidth for Application (1,5)
• Pulse Response (topology, 4)
Analog Design for Production
Comparators
Critical Factors:
1.
Passive Component Tolerances, Diode Clamp Tolerances
2.
Input Offset Voltage (Vio)
3.
Input Bias Current (Ib), Input Offset Current (Iio)
4.
Voh, Vol clamping voltages
5.
Output Slew Rate and Delay
6.
Vref Tolerance
Worst Case Analysis:
• Vutp and Vltp (upper and lower trip points, 1,2,3,4,6)
• Total hysteresis voltage (1-4,6)
• Max switching frequency (5)
Analog Design for Production
Oscillators
Critical Factors:
1.
Passive Component Tolerances
2.
Loading effects of output loads
3.
Output Slew Rate and Output Vp-p at Frequency of Oscillation
Worst Case Analysis:
• Transfer Function Analysis of any Linear Feedback Circuit
• Forward path gain Analysis at 0 or 180 deg phase response
• Mag (dB) & Phase (deg) Margins vs Frequency Plots (1,2)
• Variation of Fo (1,2)
• Power Bandwidth (3)
Analog Design for Production
Voltage Regulators, Power Supplies
Critical Factors:
1.
Passive Component Tolerances (voltage set resistors)
2.
Loading effects
3.
Input voltage DC, AC and noise levels
4.
Filtration Capacitors
5. Ambient Temperature
Worst Case Analysis:
• DC Output voltage variation (1,2,3)
• AC Output ripple, noise (2,3,4)
• Critical device power dissipation, Junction Temp (2,3,5)
• Startup Output voltage vs Input voltage vs Time (2,3,4)
• Safety Considerations