MICRONIX

Microwave AM detector MMD850

  • Photo:Microwave AM detector MMD850
    • Detection of AM signal up to 2 to 8 GHz with a dynamic range of 30 dB.
    • Evaluattion of W-CDMA, CDMA, GSM, PDC, PHS, wireless LAN, Bluetooth and wireless communication equipment including evaluation of ETC signals.

Features

  1. Faults of coaxial type AM detector
  2. Coaxial type AM detector has two disadvantages in the application indicated below :

    Coaxial type AM detector in/out characteristics
    Coaxial type AM detector in/out characteristics

    The first is that the dynamic range is narrow. The curve is non-linear when the input is more than +5dBm or less than -10dBm as shown below. Therefore, the workable range is only +15dBm. It is provided, however, that when the peak level of input is less than +5dB, -6dBm for instance, the dynamic range is even narrower and drops to 4dB. Narrow dynamic range means that the waveform is collapsed.

    Coaxial type AM detector equivalent circuit
    Coaxial type AM detector equivalent circuit

    The second is video output frequency band. The equivalent circuit of coaxial type AM detector (Rv = 1.5kohm, Co = 30pF) of a certain manufacturer is shown below. The case where observation is performed with this AM detector connected to an oscilloscope (RL = 1Mohm, CL2 = 25pF) using 1 meter coaxial cable (CL1 = 100pF) is taken into account.

    Tr = 0.35 / fb = 2.2RvRL (Co + CL1 + CL2) / (Rv + RL)

    Therefore, rising time Tr = 511 [ns] and frequency band fb = 685 [kHz]. It is learnt that the band is lower than what was imagined.

  3. Explanation of MMD850
  4. MMD850 block diagram
    MMD850 block diagram

    The block diagram of microwave AM detector MMD850 is shown below. When a microwave amplifier and linearizer are added to it, 30dB dynamic range is secured against signals of peak level more than -6dBm and up, and in addition, 10MHz bandwidth is secured without being affected by the load.

    Against signals of peak level more than -6dBm, it is possible to observe signals without spoiling the dynamic range when fixed attenuator is located to the input. If three attenuators of 3dB, 6dB and 12dB are prepared, for example, it is possible to perform observation in at least 27dB dynamic range, against signals of peak level -6dBm to +15dBm. Furthermore, due to the fact that the output impedance of the linearizer is 50ohm, it is possible to perform observation without being affected by the load, when the output is terminated with 50ohm.

    Input signals and detected output waveforms are indicated below. Example 1 is the case where continuous wave or FM wave of -6dBm is input. +1V DC voltage is produced as the detected output. Example 2 is the case where ASK signals of peak level -6dBm and bottom level -36dBm (modulation factor 94%) is input. A waveform of peak level +1V and bottom level +31.6mV is output.

    Input signal and detected output waveform
    Input signal and detected output waveform

Specification

Input characteristics
Input frequency range 2 to 8GHz
*Available for 1 to 15GHz range as special order
Optimum input level -6dBm @ peak level
Dynamic range 30dB @ -6dBm input
VSWR less than 1.4
Input damage level +13dBm
Output characteristics
Output frequency range DC to 10MHz @ -3dB
Output voltage +1.0V @ 50ohm load and -6dBm input
Polarity positive polarity
output Impedance 50Ω
General
Power source 90 to 132VAC, 50/60Hz
(Option : 180 to 250VAC)
Dimensions 320(W) x 56(H) x 350(D)mm
*excluding projections
Standard accessories Operation manual(1pc), Fuse(1pc), Power sourceCable(1pc)
Option
180 to 250VAC Power source
Coaxial Cable MC201
Coaxial Cable MC202
Coaxial Cable MC203
Fixed microwave attenuators
(1 to 10, 12, 13, 15, 20dB)
50Ω termination

Library

*MICRONIX Corporation reserves the right to make changes in design, specification and other information without prior notice.

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