 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
OP497FS Datasheet(PDF) 9 Page - Analog Devices |
|
|
|||||||||||||||||||||||||||||
OP497FS Datasheet(HTML) 9 Page - Analog Devices |
|
|
9 / 12 page  REV. D OP497 –9– 2 3 1 7 8 5 6 4 –5V +5V REF43 6 2 4 +5V R R R 2.5 V R + R RF VOUT VREF VOUT = VREF ( ) R R + R RF R 1/4 OP497 1/4 OP497 Figure 9. A Simple Bridge Conditioning Amplifier Using the OP497 NONLINEAR CIRCUITS Due to its low input bias currents, the OP497 is an ideal log amplifier in nonlinear circuits such as the square and square root circuits shown in Figures 10 and 11. Using the squaring circuit of Figure 10 as an example, the analysis begins by writing a voltage-loop equation across transistors Q1, Q2, Q3, and Q4. VIn I I VIn I I VIn I I I VIn I I T IN S T IN S T O S T REF S 1 1 2 2 3 3 4 4 + = + All the transistors of the MAT04 are precisely matched and at the same temperature, so the IS and VT terms cancel, giving: 2InI InI InI In I I IN O REF O REF =+ = × () Exponentiating both sides of thick equation leads to: I I I O IN 2 REF = () Op amp A2 forms a current-to-voltage converter which gives VOUT = R2 × IO. Substituting (VIN/R1) for IIN and the above equation for IO, yields: V R2 I V R1 OUT REF IN 2 = 1 2 3 6 7 5 C1 100pF V+ 2 3 8 1 4 V– VIN IIN C2 100pF 6 5 7 VOUT I O 9 8 10 Q1 Q3 Q2 14 12 Q4 13 –15V IREF MAT-04E R1 133k R2 33k R3 50k R4 50k 1/4 OP497 1/4 OP497 Figure 10. Squaring Amplifier A similar analysis made for the square-root circuit of Figure 11 leads to its transfer function: VR2 VI R1 OUT IN REF = ()( ) In these circuits, IREF is a function of the negative power sup- ply. To maintain accuracy, the negative supply should be well regulated. For applications where very high accuracy is required, a voltage reference may be used to set IREF. An important con- sideration for the squaring circuit is that a sufficiently large input voltage can force the output beyond the operating range of the output op amp. Resistor R4 can be changed to scale IREF, or Rl and R2 can be varied to keep the output voltage within the usable range. 1 2 3 6 7 5 C1 100pF V+ 2 3 8 1 4 V– 6 5 7 VOUT IO 9 8 10 Q1 Q3 Q2 14 12 Q4 13 –15V IREF MAT-04E IIN VIN R1 33k R2 33k R5 2k R3 50k R4 50k C2 100pF 1/4 OP497 1/4 OP497 Figure 11. Square-Root Amplifier Unadjusted accuracy of the square-root circuit is better than 0.1% over an input voltage range of 100 mV to 10 V. For a similar input voltage range, the accuracy of the squaring circuit is better than 0.5%. |
|
|
Link URL |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link to Datasheet | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
