AD831AP Analog Devices Inc, AD831AP Datasheet - Page 9

• 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

For gains other than unity, the amplifier’s output at OUT is
connected via an attenuator network to VFB; this determines
the overall gain. Using resistors R1 and R2 (Figure 6), the gain
setting expression is
Driving Filters
The output amplifier can be used for driving reverse-terminated
loads. When driving an IF band-pass filter (BPF), for example,
proper attention must be paid to providing the optimal source
and load terminations so as to achieve the specified filter response.
The AD831’s wideband highly linear output amplifier affords an
opportunity to increase the RF to IF gain to compensate for a
filter’s insertion and termination losses.
Figure 7 indicates how the output amplifier’s low impedance
(voltage source) output can drive a doubly terminated band-pass
filter. The typical 10 dB of loss (4 dB of insertion loss and 6 dB
due to the reverse-termination) be made up by the inclusion of a
feedback network that increases the gain of the amplifier by
10 dB (3.162). When constructing a feedback circuit, the signal
path between OUT and VFB should be as short as possible.
REV. C
G
Figure 6. Output Amplifier Feedback Connections
for Increasing Gain
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(2)
–9–
Higher gains can be achieved, using different resistor ratios, but
with concomitant reduction in the bandwidth of this amplifier
(Figure 8). Note also that the Johnson noise of these gain setting
resistors, as well as that of the BPF terminating resistors, is ulti-
mately reflected back to the mixer’s input; thus they should be as
small as possible, consistent with the permissible loading on the
amplifier’s output.
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Figure 7. Connections for Driving a DoublyTerminated
Band-Pass Filter
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Figure 8. Output Amplifier 1 dB Compression
Point for Gains of 1, 2, and 4 (Gains of 0 dB, 6 dB,
and 12 dB, Respectively)
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FREQUENCY (MHz)
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