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Single-Chip VHF RF Preamp(MAX2633)

2017-08-06 00:19  
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This article briefly describes the Single-Chip VHF RF Preamp (MAX2633). This principle is easy to understand, but also very practical. Depth understanding of circuit elements, can be more effective to grasp this principle. Do you know the circuit, for example, can understand and buy these components: MAX2633 .

Here is a high performance RF amplifier for the entireVHFbroadcast andPMRband (100-175 MHz) which can be successfully built without any special test equipment. The grounded-gate configuration is inherently stable without any neutralization if appropriatePCBlayout 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 amateurVHFstations 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 fromVHFtoSHFfrequencies.

Circuit diagram:

Figure:1 Single-Chip VHF RF Preamp Circuit Diagram

Figure 1 Single-ChipVHFRF Preamp Circuit Diagram

Operating from a single 2.7 V 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 aVCCbypass 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: http://www.maxim-ic.com.



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