AD831AP Analog Devices Inc, AD831AP Datasheet - Page 8

• Manufacturer Part Number: AD831AP
• Description: LOW DISTORTION 500 MHZ MIXER IC
• Manufacturer: Analog Devices Inc
• Series: AD831r

Specifications of AD831AP

• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• Rohs Status: RoHS non-compliant
• Rf Type: HF, VHF
• Frequency: 500MHz
• Number Of Mixers: 1
• Gain: 0dB
• Noise Figure: 14dB
• Secondary Attributes: Down Converter
• Current - Supply: 125mA
• Voltage - Supply: 4.5 V ~ 5.5 V
• Package / Case: 20-LCC (J-Lead)
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

The mixer has two open-collector outputs (differential currents) at
pins IFN and IFP.These currents may be used to provide nominal
unity RF to IF gain by connecting a center-tapped transformer
(1:1 turns ratio) to pins IFN and IFP as shown in Figure 2.
Programming the Bias Current
Because the AD831’s RF port is a Class-A circuit, the maximum
RF input is proportional to the bias current. This bias current
may be reduced by connecting a resistor from the BIAS pin to the
positive supply (Figure 3). For normal operation, the BIAS pin is
left unconnected. For lowest power consumption, the BIAS pin is
connected directly to the positive supply. The range of adjustment
is 100 mA for normal operation to 45 mA total current at minimum
power consumption.
AD831
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Figure 2. Connections forTransformer Coupling to
the IF Output
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Figure 3. Programming the Quiescent Current
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Low-Pass Filtering
A simple low-pass filter may be added between the mixer and
the output amplifier by shunting the internal resistive loads
(an equivalent resistance of about 14  with a tolerance of 20%)
with external capacitors; these attenuate the sum component in
a downconversion application (Figure 4). The corner frequency
of this one-pole low-pass filter (f = (2  RC
about an octave above the difference frequency IF. Thus, for a
70 MHz IF, a –3 dB frequency of 140 MHz might be chosen,
using C
standard value.
Using the Output Amplifier
The AD831’s output amplifier converts the mixer core’s differential
current output into a single-ended voltage and provides an output
as high as ±1 V peak into a 50 V load (+10 dBm). For unity gain
operation (Figure 5), the inputs AN and AP connect to the open-
collector outputs of the mixer’s core and OUT connects to VFB.
Figure 4. Low-Pass Filtering Using External Capacitors
Figure 5. Output Amplifier Connected for Unity
Gain Operation
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REV. C