lmx5080mx National Semiconductor Corporation, lmx5080mx Datasheet - Page 4
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lmx5080mx
Manufacturer Part Number
lmx5080mx
Description
Pllatinum? 2.7 Ghz Low Power Dual Modulus Prescaler For Rf Personal Communications
Manufacturer
National Semiconductor Corporation
Datasheet
1.LMX5080MX.pdf
(7 pages)
www.national.com
Functional Description
The basic phase-lock-loop (PLL) configuration using an ex-
ternal prescaler consists of a high-stability crystal reference
oscillator, a prescaler such as the National Semiconductor
LMX5080, a low frequency synthesizer, a voltage controlled
oscillator (VCO), and a loop filter. The frequency synthesizer
typically includes programmable reference [R] and feedback
[N] frequency dividers, a phase detector, as well as a charge
pump. The MC signal is fed back to the prescaler from either
Block Diagram
4
the low frequency synthesizer, or a controller to set the pres-
caler divide ratio to N or N+2. The prescaler output fre-
quency is established by dividing the VCO signal down via
the prescaler modulus. The RF inputs to the prescalar con-
sist of the Fin and /Fin input pins which are complementary
inputs to a differential pair amplifier. This configuration can
operate to 2 GHz with an input sensitivity of −15 dBm.
DS100940-3