AD831 Mixer

By | 15th August 2017

I bought a pair of AD831 pre-assembled modules from China,  $10 each – not bad considering the price of the individual AD831 chip, the board comes ready to use “plug and play” with all ports terminated in to 50 ohms with SMA connectors – neat.

Testing the mixer saw excellent results and the added bonus of some gain, around 10dB for a 9V supply – I tried them at 12V but got too warm for my liking, even at 9V they still got relatively hot to the touch.

One thing I will have to remember is local oscillator drive – these active mixers will perform with as little as -10dB drive!

Here is the spec taken from the supplier on aliexpress.com

AD831 is a low distortion, wide dynamic range, single-chip mixers, such as the frequency for lower HF and VHF receiver RF-IF, DMR base station in a second mixer, DC – baseband conversion, quadrature modulation and demodulation, and ultrasound imaging of the Doppler shift detection applications.

Product Features

AD831 provides +24 dBm third-order intercept point, -10 dBm LO power consumption can be achieved without high power LO drive, there was no corresponding mask and isolate problems, as compared with the passive mixer can be improved system performance and reduce system cost.

The mixer designed for single power supply, RF, IF, and LO port has a DC blocking capacitors, easy to use. RF and LO input operating frequency up to 500MHz. IF output is single-ended voltage output. With a 250 MHz output bandwidth. A single resistor connected between OUT and FB pin is used to set the gain. The amplifier has a low dc offset feature, which can be used in DC – baseband conversion and quadrature amplitude demodulation DC-coupled applications.

When the mixer output amplifier and optimum source impedance, the mixer’s SSB noise figure at 70 MHz when 10.3 dB. Passive mixer different, AD831 insertion loss not exist without an external diplexer does not need to be a passive termination.

 

Technical Specifications

  •     RF input: 0.1-500MHz
  •     RF input: + 10dBm (1dB compression point)
  •     LO input: 0.1-500MHz
  •     LO input: -10dBm
  •     IF output: 0.1-200MHz (It is actually DC-200MHz)
  •     Supply voltage: 9–11V Single Ended

AD831 Active Mixer

2 thoughts on “AD831 Mixer

  1. M.Salzwedel

    Hi AD831 users.
    I bought and want to use the AD831 to mix very low frequencies ( next to DC, mHz ) with a sound frequency like 1000 Hz. The offered AD831 has a blocking C. So it cannot work from DC to some Mhz. Can the blocking C be shorted to make it work from DC>> ? What input voltages for the RFin and LOin should be used to get good results?
    Thanks for any answer and help,
    OH/DK4ZC

    Reply
    1. qrp73

      According to the datasheet, AD831 has the following impedance:
      – RF input = 1.3 [kOhm]
      – LO input = 500 [Ohm]
      – IF output = 100 [Ohm]
      So, you’re need to add impedance match circuit, in order to replace capacitors.

      Reply

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