Electronic Components Datasheet Search |
|
ADL5902 Datasheet(PDF) 3 Page - Analog Devices |
|
ADL5902 Datasheet(HTML) 3 Page - Analog Devices |
3 / 5 page Circuit Note CN-0178 Rev. A| Page 3 of 5 The calibration is performed by applying four known signal levels to the ADL5902 and measuring the corresponding output codes from the ADC. The calibration points chosen should be within the linear operating range of the device. In this example, calibration points at 0 dBm, −20 dBm, −45 dBm, and −58 dBm were used. The SLOPE and INTERCEPT calibration coefficients are calculated using the equations SLOPE1 = ( CODE _1 – CODE_2)/(PIN_1 − PIN_2) INTERCEPT1= CODE_1/(SLOPE_ADC × PIN_1) This calculation is then repeated using CODE_2/CODE_3 and CODE_3/CODE_4 to calculate SLOPE2/INTERCEPT2 and SLOPE3/INTERCEPT3, respectively. The six calibration coefficients should then be stored in NVM along with CODE_1, CODE_2, CODE_3, and CODE_4. When the circuit is in operation in the field, these calibration coefficients are used to calculate an unknown input power level, PIN, using the equation PIN = (CODE/SLOPE) + INTERCEPT In order to retrieve the appropriate SLOPE and INTERCEPT calibration coefficients during circuit operation, the observed CODE from the ADC must be compared to CODE_1, CODE_2, CODE_3, and CODE_4. For example if the CODE from the ADC is between CODE_1 and CODE_2, then the SLOPE1 and INTERCEPT1 should be used. This step can also be used to provide an underrange or overrange warning. For example, if the CODE from the ADC is greater than CODE_1 or less than CODE_4, it indicates that the measured power is outside of the calibration range Figure 3 also shows the transfer function variation of the circuit vs. the above straight line equations. This error function is caused by bending at the edges of the transfer function, small ripple in the linear operating range, and drift over temperature. The error is expressed in dB using the equation Error (dB) = Calculated RF Power − True Input Power = (CODE/SLOPE) + INTERCEPT – PIN_TRUE Figure 3 also includes plots of error vs. temperature. In this case the measured ADC codes at +85°C and −40°C are compared to the straight line equations at ambient. This is consistent with a real world system where system calibration is generally only practical at ambient temperature. Figure 4 and Figure 5 show the performance of the circuit at 1 GHz and 2.2 GHz, respectively. 4096 3755 3413 3072 2731 2389 2048 1707 1365 1024 683 341 0 6 5 4 3 2 1 0 –1 –2 –3 –4 –5 –6 –70 –60 –50 –40 –30 –20 –10 0 10 PIN (dBm) +85°C CODE –40°C CODE +25°C CODE +25°C ERROR 4-POINT CAL @ 0dBm, –20dBm, –45dBm, AND, –58dBm +85°C ERROR 4-POINT CAL –40°C ERROR 4-POINT CAL Figure 4. ADC Output Code and Error vs. RF Input Power @ 1 GHz 4096 3755 3413 3072 2731 2389 2048 1707 1365 1024 683 341 0 6 5 4 3 2 1 0 –1 –2 –3 –4 –5 –6 –70 –60 –50 –40 –30 –20 –10 0 10 PIN (dBm) +85°C CODE –40°C CODE +25°C CODE +25°C ERROR 4-POINT CAL @ 0dBm, –20dBm, –45dBm, AND, –58dBm +85°C ERROR 4-POINT CAL –40°C ERROR 4-POINT CAL Figure 5. ADC Output Code and Error vs. RF Input Power @ 2.2 GHz The performance of this or any high speed circuit is highly dependent on proper PCB layout. This includes, but is not limited to, power supply bypassing, controlled impedance lines (where required), component placement, signal routing, and power and ground planes. (See MT-031 Tutorial, MT-101 Tutorial, and article, A Practical Guide to High-Speed Printed-Circuit- Board Layout, for more detailed information regarding PCB layout.) A complete design support package for this circuit note can be found at www.analog.com/CN0178-DesignSupport. |
Similar Part No. - ADL5902 |
|
Similar Description - ADL5902 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | 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 |