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Hot-carrier diode substitute

Discussion in 'Electronic Design' started by garyr, Jun 8, 2013.

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  1. garyr

    garyr Guest

    I want to make a simple rectifier for an RF signal, frequency less than 10
    MHz. The schematic below (view with fixed font) is from an article
    describing a circuit useable with much higher frequencies and used a
    hot-carrier diode (1N5711). For relative low frequencies would a general
    purpose diode such as a 1N4148 be adequate?

    If a hot-carrier would be necessary I have a problem because I don't have
    any but I do have a few high speed transistors: BSV52, BSF17, J310. Would
    the base-emitter or base-collector junction of one of these transistors be a
    suitable substitute for a hot-carrier diode?

    |
    \
    /R2 (20 uA bias current)
    \
    C1 | R2 R3
    -||-+-/\/\-+-/\/\-
    | |
    v D1 = C2
    - |
    | Gnd
    Gnd
     
  2. garyr

    garyr Guest

    I don't understand your diff-pair detector. Could you elaborate a bit?
     
  3. garyr

    garyr Guest

    I didn't realize that a hot-carrier was a type of schottky diode. I
    actually have a few SD101BW-TP schottky diodes which, according to the spec,
    have 2.1 pF capacitance at zero volts and a maximum forward voltage drop at
    1 ma of 0.4 volts. They should be OK.

    My circuit will have about 30 dB gain ahead of the detector (two MMICs) and
    an opamp to buffer the output and provide some gain.

    Thanks for the info.
     
  4. LM

    LM Guest

    I have used a 1N4148 at VHF frequencies. I am sure something like
    1N5711 is better or atleast better with low level signals but you get
    DC out with 1N4148 too.
     
  5. miso

    miso Guest

    The first circuit is known as the junk buffer.

    I'm amazed that got past the patent office. It is basically the well
    known sat catcher circuit. You find them in LDOs. Then again, they are
    still patenting sat catchers, even with all the prior art. But nobody is
    going to court over them.
     
  6. garyr

    garyr Guest

    Thanks for the information and the offer. My application is not critical so
    almost any diode would probably be OK.
     
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