Tuesday, April 9, 2013

Browse » home» » » » » » Single Chip VHF RF Preamp

Single Chip VHF RF Preamp

Here is a high
performance RF amplifier for the entire VHF broadcast and PMR band
(100-175 MHz) which can be successfully built without any special test
equipment. The grounded-gate configuration is inherently stable without
any neutralization if appropriate PCB layout techniques are employed.
The performance of the amplifier is quite good. The noise figure is
below 2 dB and the gain is over 13 dB. The low noise figure and good
gain will help car radios or home stereo receivers pick up the
lower-power local or campus radio stations, or distant amateur VHF
stations in the 2-metres band. Due to the so-called threshold effect, FM
receivers loose signals abruptly so if your favourite station fades in
and out as you drive, this amplifier can cause a dramatic improvement.
The MAX2633 is a low-voltage, low-noise amplifier for use from VHF to
SHF frequencies.

Single-Chip VHF RF Preamp circuit schematic

from a single +2.7V to +5.5V supply, it has a virtually flat gain
response to 900 MHz. Its low noise figure and low supply current makes
it ideal for RF receive, buffer and transmit applications. The MAX2633
is biased internally and has a user-selectable supply current, which
can be adjusted by adding a single external resistor (here, R1). This
circuit draws only 3 mA current. Besides a single bias resistor, the
only external components needed for the MAX2630 family of RF amplifiers
are input and output blocking capacitors, C1 and C3, and a VCC bypass
capacitor, C2. The coupling capacitors must be large enough to
contribute negligible reactance in a 50-? system at the lowest
operating frequency. Use the following equation to calculate their
minimum value: Cc = 53000/ flow [pF]. Further information:

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.