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    How is the wire routed on this evaluation board

    ?? I am not worried about N/C pin. All I concerned is the SI pin. I want to know how is the trace coming out of SI pin routed.
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    How is the wire routed on this evaluation board

    I am now working on designing an evaluation board for a capacitve read out chip since the board is no longer fabricated by the manufacture. The board is used to measure extremely small capacitance difference between external capacitors. The picture of the board is shown below. I am not sure...
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    Interesting wiring in designing an evaluation board for a capacitive readout sensor

    Thanks for your reply. Pin 1(op amp output) and pin 2(inverting input) are connected together which have the same voltage. Typically I think we can consider pin 2(inverting input) and pin 3(non-inverting input) have the same voltage for an op amp. That's why I said the three pins have same...
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    Interesting wiring in designing an evaluation board for a capacitive readout sensor

    I think you are right, SI is an input. But the point I marked is SI, I am pretty sure about that. I am sorry I should mention that the pinout connection you see in the manual is for PGA64 package, while the evaluation board circuit diagram is for LQFP48 package which is also the package type of...
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    Interesting wiring in designing an evaluation board for a capacitive readout sensor

    Thanks for your reply. The manual is in Janpanese, I am not sure if it will help. The manual can be found at http://www.actlsi.co.jp/pdf/at1006_manual.pdf, it's too large to be attached. SI is the common point of two capacitors, it actually is connected to another op amp's non-inverting input...
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    Interesting wiring in designing an evaluation board for a capacitive readout sensor

    Hi, Please allow me to describe my situation first.I recently bought a capacitve readout sensor from a small Japanese company. Although this product is no longer manufactured several years ago, the company still has some inventory, so I could get some chip, but no evaluation board and no...
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    Need help on the evaluation board of a capacitive readout chip

    This circuit is to measure the tiny capacitance difference between two capacitor with very high accuracy,and typically on the fF scale. As you said, in order to reduce noise, I should always put a jumper to connect the ground with Frame ground?
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    Need help on the evaluation board of a capacitive readout chip

    Actually this evaluation board is no more fabricated several years ago. What I have now is just a picture and diagram. I am trying to build an evaluation board by myself.
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    Need help on the evaluation board of a capacitive readout chip

    Hi, I recently bought a capacitive sensor readout from a Japanese company. They sent me an evaluation board diagram like following, I magnified the part in the red box. The corresponding evaluation board picture is as follows. The lower right corner corresponds to the part in the red box...
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    LQFP48 footprint

    Hi, I recently bought some chips packaged with LQFP48. The manufacture doesn't provide the footprint information. I wonder if the footprint dimension is same for all the LQFP48 packaged chip？ Thanks.
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    Question about layout of a PCB

    The lighter area is like what you said where there is no copper fill.And it works as ground plane. But that makes me confused. Ground plane is used to reduce noise and prevent crosstalk, for measuring very small capacitance, I think ground plane is vital. But why in the evaluation board, the...
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    Question about layout of a PCB

    Hi all, I have a chip used to measure small capacitance(aF to pF). Below is its evaluation board. The area inside the red box is where I have question with. It is basically a connect lead used to connect to the capacitors being measured. A magnified version I have two questions: 1. Why...
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    How to purchase a electronic component oversea

    Hi I would like to buy an IC called AT-1006 manufactured by a Japanese company(ACT-LSI) which has no distributor in U.S. or Europe. I wonder is that possible that I entrust a electronic distributor in U.S. to purchase that for me? Has anyone done something similar before? Thanks.
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    Switch capacitor = low pass filter ?

    Thanks for your reply. I brought up this question because a manual I am reading said"The circuit is a one pole, 32KHz, switched-capacitor LPF that functions as a sample/hold circuit." But it didn't show the circuit diagram in the manual. Now I think the switched capacitor LPF should be as you...
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    Switch capacitor = low pass filter ?

    I understand that a switched-capacitor can be analog to a resistor with value R = 1/C*f, but I really don't see how can a switched-capacitor work as a low pass filter, could anyone give some explanation?
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    Which one has the lower noise level？Wheatstone bridge or direct measurement?

    Hi, In the Whetstone bridge circuit: If the circuit is balanced (and all resistances known), and we measure Vg as a function of time, then the fluctuations correspond to 4KbTR the well-known thermal fluctuations. My question:1.what should be used for R here? 2.And if...
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    Oscilloscope sampling rate

    Hi, I am using the Tektronix TDS 2024B oscilloscope, which has the maximum sample rate of 2GS/s. The manual also says it has a 2500 point record length for each channel. I know the sample rate is related to sec/div setting. I am interested in the actual sample rate with different sec/div...
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    interesting thing about oscilloscope at different SEC/DIV

    I did the thing as you said and did observe different waveform for 500ms. For 800Hz, For 15kHz, I also test other frequency, but I didn't show it here. However, for sec/div is 50s, I could always get the right amplitude but wrong frequency. For 800Hz, For 15kHz, I think you are right, it...
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    interesting thing about oscilloscope at different SEC/DIV

    Hi, I use oscilloscope to measure a 1000Hz 6Vpp AC signal. I observed different traces shown on the oscilloscope screen which is interesting. When sec/div is 1ms, When sec/div is 5ms, When sec/div is 100ms, When sec/div is 250ms. When the sec/div is 50s, Observation: 1.As you can see...
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    question about ohm's law

    Hi, About Ohm's law, wikipedia has the following statement “Materials and components that obey Ohm's law are described as "ohmic" which means they produce the same value for resistance (R = V/I) regardless of the value of V or I which is applied and whether the applied voltage or current is DC...
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