anushaas
Member level 5
Hi,
I am using an AD8302 IC for gain and phase measurement of two signal inputs within a frequency range of 1Hz to 1MHz.
It is mentioned in the Application Note AN-691 that the IC need to be used in the following configuration to enable its use in low frequency applications.
![1.png 1.png](https://www.edaboard.com/data/attachments/56/56276-e852e19dc1626da8766a042563eb6dd8.jpg)
I used a +5V supply,CC= 10uF and CFLT = 1uF.Also R1=R2 =51.9 Ohm.
The signal inputs were VINA =VF1 and VINB = VF2 as shown in the following circuit:
![2.png 2.png](https://www.edaboard.com/data/attachments/56/56277-e68fd08ce0ea9239575da659bca2dd4d.jpg)
The voltage outputs of AD8302 corresponds to Gain and Phase measurements as per the following equations given in datasheet:
![3.png 3.png](https://www.edaboard.com/data/attachments/56/56278-792368c6d4da9cb88fe0712ffc5fcb16.jpg)
where VCP =900mV,RFISLP = 600mV/decade and RFIQ = 10mV/degree as per datasheet at low frequencies.
I acquired a bode plot for the same circuit using the Bode Analyser of NI Elvis II+ and also obtained the Gain in dB and Phase in degree using the above equations from the AD8302 output voltages.
The graphs obtained were as follows:
![4.png 4.png](https://www.edaboard.com/data/attachments/56/56279-8cf9b5fafa1eb7905c227ec518047f58.jpg)
![5.png 5.png](https://www.edaboard.com/data/attachments/56/56280-87568aa09cce825bfb03720f2b4e8336.jpg)
Can anyone please suggest ways to reduce the error in the gain and phase measurements?
I am using an AD8302 IC for gain and phase measurement of two signal inputs within a frequency range of 1Hz to 1MHz.
It is mentioned in the Application Note AN-691 that the IC need to be used in the following configuration to enable its use in low frequency applications.
![1.png 1.png](https://www.edaboard.com/data/attachments/56/56276-e852e19dc1626da8766a042563eb6dd8.jpg)
I used a +5V supply,CC= 10uF and CFLT = 1uF.Also R1=R2 =51.9 Ohm.
The signal inputs were VINA =VF1 and VINB = VF2 as shown in the following circuit:
![2.png 2.png](https://www.edaboard.com/data/attachments/56/56277-e68fd08ce0ea9239575da659bca2dd4d.jpg)
The voltage outputs of AD8302 corresponds to Gain and Phase measurements as per the following equations given in datasheet:
![3.png 3.png](https://www.edaboard.com/data/attachments/56/56278-792368c6d4da9cb88fe0712ffc5fcb16.jpg)
where VCP =900mV,RFISLP = 600mV/decade and RFIQ = 10mV/degree as per datasheet at low frequencies.
I acquired a bode plot for the same circuit using the Bode Analyser of NI Elvis II+ and also obtained the Gain in dB and Phase in degree using the above equations from the AD8302 output voltages.
The graphs obtained were as follows:
![4.png 4.png](https://www.edaboard.com/data/attachments/56/56279-8cf9b5fafa1eb7905c227ec518047f58.jpg)
![5.png 5.png](https://www.edaboard.com/data/attachments/56/56280-87568aa09cce825bfb03720f2b4e8336.jpg)
Can anyone please suggest ways to reduce the error in the gain and phase measurements?