Ultralow Noise Synthesizers LTC6946 REF OSC VCO Output Divider PLL Low Noise and Spurious Levels, 350MHz to 6.39GHz Frequency Synthesizers Our new ultralow noise, integer-N frequency synthesizers provide best-in-class phase noise and spurious performance. The LTC®6946 is a complete frequency synthesizer that includes a high performance, low noise, 6.39GHz phase-locked loop (PLL) with a fully integrated, low phase noise VCO. The LTC6945 separates the low 1/f corner PLL core for use with an external VCO up to 6GHz. The free, easy-to-use PLLWizard™ CAD tool quickly and accurately simulates synthesizer performance to ensure an optimal design. LTC6946-3 PLL Phase Noise Features nn nn nn nn nn nn nn nn Integrated VCO, Up to 6.39GHz (LTC6946) 350MHz to 6GHz VCO Input Range (LTC6945) Low –226dBc/Hz Normalized In-Band Phase Noise Floor –157dBc/Hz Wideband Output Phase Noise Floor Industry’s Lowest –274dBc/Hz Normalized In-Band 1/f Noise Spurious Levels < –100dBc High Current 11mA Output Charge Pump Minimizes Loop Compensation Thermal Noise Programmable Output Divider for Wide Operating Frequency Range 28-Pin (4mm × 5mm) QFN Packages –80 –90 PHASE NOISE (dBc/Hz) nn –100 –110 –120 –130 RMS NOISE = 0.61° –140 RMS JITTER = 296fs fRF = 5.7GHz –150 fPFD = 10MHz BW = 85kHz –160 1M 100 1k 10k 100k OFFSET FREQUENCY (Hz) Frequency Coverage Options LTC6946-1 LTC6946-2 LTC6946-3 LTC6946-4 VCO Frequency (GHz) 2.240 to 3.740 3.080 to 4.910 3.840 to 5.790 4.200 to 6.390 OUT DIV = 1 2.240 to 3.740 3.080 to 4.910 3.840 to 5.790 4.200 to 6.390 OUT DIV = 2 1.120 to 1.870 1.540 to 2.455 1.920 to 2.895 2.100 to 3.195 OUT DIV = 3 0.747 to 1.247 1.027 to 1.637 1.280 to 1.930 1.400 to 2.130 OUT DIV = 4 0.560 to 0.935 0.770 to 1.228 0.960 to 1.448 1.050 to 1.598 OUT DIV = 5 0.448 to 0.748 0.616 to 0.982 0.768 to 1.158 0.840 to 1.278 OUT DIV = 6 0.373 to 0.623 0.513 to 0.818 0.640 to 0.965 0.700 to 1.065 L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and PLLWizard is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. 10M 40M LTC6946-X Frequency Synthesizer Block Diagram V+ (3.3V) REF INPUT (10MHz to 250MHz) • Single-Ended or Differential • Sine Wave or Logic REF IN Proprietery noise-limiting input section delivers optimal phase noise performance with sine wave input signals. VCP+ (5V) ÷1 to 1023 ≤ 100MHz R_DIV PFD Low noise charge pump with programmable output current up to 11mA CP CH PUMP LOCK IND REF OUT N_DIV Buffered REF OUT (10MHz to 250MHz) VCO TUNE ÷32 to 65535 SDO SPI Serial Port Configurable Status Output On-chip temperaturecompensated VCO (external on LTC6945). Never needs recalibration. SCLK SDI Normalized in-band phase noise floor = –226dBc/Hz Serial Port ÷1 to 6 CS STAT Programmable output divider settable to any integer from 1 to 6. RF OUT OUT_DIV GND Mutable output amplifier controlled via dedicated pin or serial port MUTE Programmable output divider gives each part broad frequency coverage. Output is always 50% duty cycle. PLLWizard Tool Provides Design Support Design Features nn nn nn nn nn Find Part Parameters Based on Your Frequency Plan Design Noise-Optimized Loop Filters Simulate Loop Frequency Response and Stability Simulate VCO and Reference Source Noise Simulate Output Noise Characteristics and Statistics Evaluation Features nn nn nn nn Read and Write All Device Registers Configure Using a Block Diagram Programming Interface Troubleshoot Common Set-Up Problems Receive Alerts Due to Programming Errors www.linear.com/pllwizard www.linear.com/6946 n 1-800-4-LINEAR 0315B