AD831APZ-REEL7 Analog Devices Inc, AD831APZ-REEL7 Datasheet - Page 7

• Manufacturer Part Number: AD831APZ-REEL7
• Description: MIXER IC
• Manufacturer: Analog Devices Inc
• Series: AD831r

Specifications of AD831APZ-REEL7

• 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: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

THEORY OF OPERATION
The AD831 consists of a mixer core, a limiting amplifier, a low
noise output amplifier, and a bias circuit (Figure 1).
The mixer’s RF input is converted into differential currents by
a highly linear, Class A voltage-to-current converter, formed by
transistors Q1, Q2 and resistors R1, R2. The resulting currents
drive the differential pairs Q3, Q4 and Q5, Q6. The LO input is
through a high gain, low noise limiting amplifier that converts the
–10 dBm LO input into a square wave. This square wave drives
the differential pairs Q3, Q4 and Q5, Q6 and produces a high
level output at IFP and IFN—consisting of the sum and differ-
ence frequencies of the RF and LO inputs—and a series of lower
level outputs caused by odd harmonics of the LO frequency mix-
ing with the RF input.
An on-chip network supplies the bias current to the RF and LO
inputs when these are ac-coupled; this network is disabled when
the AD831 is dc-coupled.
REV. C
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When the integral output amplifier is used, pins IFN and IFP
are connected directly to pins AFN and AFP; the on-chip load
resistors convert the output current into a voltage that drives
the output amplifier. The ratio of these load resistors to resistors
R1, R2 provides nominal unity gain (0 dB) from RF-to-IF. The
expression for the gain, in decibels, is
where:
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is the amplitude of the fundamental component of a
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is the conversion loss.
is the small signal dc gain of the AD831 when the LO input
is driven fully positive or negative.
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AD831
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