TI adds phase detector and PLL to precision
The LMX2581 is an ultra low noise wideband frequency synthesizer which integrates a delta-sigma fractional N PLL, a VCO with fully integrated tank circuit, and an optional frequency divider.
The LMX2581 integrates several low-noise, high precision LDOs to provide superior supply noise immunity and more consistent performance. When combined with a high quality reference oscillator, the LMX2581 generates a very stable, ultra low noise signal. The internal VCO can be bypassed so that an external VCO can be used.
- 50 – 3760 MHz Operating Frequency
- Low Voltage Logic Compatibility
- Digital Lock Detect
- 32 Pin QFN Package
High Performance PLL
- –229 dBc/Hz Normalized PLL Phase Noise
- –120.8 dBc/Hz Normalized PLL 1/f Noise
- 200 MHz Maximum Phase Detector Frequency
- Programmable Charge Pump Current
Broadband Multi-Core VCO
- Tuning Range: 1880 – 3760 MHz
- –137 dBc/Hz Phase Noise @ 1 MHz for a 2.5 GHz Carrier
- Programmable Output Power
- Programmable Option to Use an External VCO
Low Noise VCO Divider
- Programmable to divide by 1 (bypass), 2, 4, 6, 8, … , 38
- –155 dBc/Hz Noise Floor
Texas Instruments has introduced a wideband frequency synthesiser with integrated low phase-noise voltage-controlled oscillator.
The device combines a low noise phase-locked loop (PLL) and a phase detector in a frequency synthesiser that outputs 50 to 3760 MHz.
Designated the LMX2581, the chip’s phase detector frequency of 200MHz and PLL normalised phase noise of -229dBc/Hz provides a precision local oscillator for RF front ends.
The integrated VCOs allow the device to output frequencies from 50MHz to 3760MHz, eliminating the multiple VCO/PLL combinations typically required to support a broad range of applications.
There is also the option to bypass its internal multi-core VCO in favour of an external VCO.
The frequency synthesiser integrates a delta-sigma fractional-N PLL; a multi-core VCO with tank circuit; optional frequency divider; two differential RF output buffers that can deliver 10 dBm single-ended on each side; and several low-noise, high precision low dropout regulators (LDOs).
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