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Part Number: JFE150EVM Other Parts Discussed in Thread: OPA202 , , JFE150 Hi, I note in the JFE150EVM there's an LC on the supply input, with a corner around 1 kHz or so. I'm wondering with 60 dB of gain how sensitive the Figure 4-1 circuit in the JFE150…
Hi Yang,
The capacitor around the OPA202 isn't currently doing anything because the corner frequency is in the 1/beta curve and comes after the OPA202 aol corner created by the miller cap. I put it in the app note and the EVM for the circuit as a placeholder…
Hey Itmar,
It is hard to say why they would not have aligned however that is surprising. It is possible the antenna model is not accurate. My other suspicions would be the biasing of the JFETs, common mode input voltage was exceeded or output signal was…
Hey Camille,
You may consider adding an LC filter similar to what I did on my JFE150EVM. There is a much more detailed explanation in the video link below on power supply filtering.
https://www.ti.com/video/3872230260001
The inductor value I used for…
Hi Santosh,
One thing I noticed in your calculations is that VCC is 3V. Is that correct? Do you know what the minimum drain to source bias voltage is for the JFET internal to the microphone? As an example, you can see below that there are two modes of…
Hi Jeremie,
I am the engineer who wrote the app note. I will be out of office for the next week and will be returning on July 22nd at which point I can address some of these questions. Most of the questions are addressed in the Grey and Meyer text for…
Hi Craig,
Cool project! You are considering some important tradeoffs on the devices. Unfortunately I can't seem to find a plot showing the Vos vs Vcm data for the OPA1652 but I have experience with the device. The OPA1688 does have the Vos vs Vcm curve…
Hey Andrew,
The OPA1642 has much lower current noise and better 1/f noise than the OPA1656. For high source impedance sensors such as a phono cartridge lower current noise is better. The current noise paired with high source impedance translates into additional…
