Electronic Components Datasheet Search |
|
SA7016DH Datasheet(PDF) 9 Page - NXP Semiconductors |
|
SA7016DH Datasheet(HTML) 9 Page - NXP Semiconductors |
9 / 18 page Philips Semiconductors Product specification SA7016 1.3GHz low voltage fractional-N synthesizer 1999 Nov 04 9 Main Output Charge Pumps and Fractional Compensation Currents (see Figure 6) The main charge pumps on pins PHP and PHI are driven by the main phase detector and the charge pump current values are determined by the current at pin RSET in conjunction with bits CP0, CP1 in the B-word (see table of charge pump ratios). The fractional compensation is derived from the current at RSET, the contents of the fractional accumulator FRD and by the program value of the FDAC. The timing for the fractional compensation is derived from the main divider. The main charge pumps will enter speed up mode after the A-word is set and strobe goes High. When strobe goes Low, charge pump will exit speed up mode. Principle of Fractional Compensation The fractional compensation is designed into the circuit as a means of reducing or eliminating fractional spurs that are caused by the fractional phase ripple of the main divider. If ICOMP is the compensation current and IPUMP is the pump current, then for each charge pump: IPUMP_TOTAL = IPUMP + ICOMP. The compensation is done by sourcing a small current, ICOMP, see Figure 7, that is proportional to the fractional error phase. For proper fractional compensation, the area of the fractional compensation current pulse must be equal to the area of the fractional charge pump ripple. The width of the fractional compensation pulse is fixed to 128 VCO cycles, the amplitude is proportional to the fractional accumulator value and is adjusted by FDAC values (bits FC7–0 in the B-word). The fractional compensation current is derived from the main charge pump in that it follows all the current scaling through external resistor setting, RSET, programming or speed-up operation. For a given charge pump, ICOMP = ( IPUMP / 128 ) * ( FDAC / 5*128) * FRD FRD is the fractional accumulator value. The target values for FDAC are: 128 for FMOD = 1 (modulo 5) and 80 for FMOD = 0 (modulo 8). SR01416 REFERENCE R MAIN M DIVIDE RATIO DETECTOR OUTPUT ACCUMULATOR FRACTIONAL COMPENSATION CURRENT OUTPUT ON PUMP N N N+1 N N+1 24 1 3 0 PULSE WIDTH MODULATION PULSE LEVEL MODULATION mA µA NOTE: For a proper fractional compensation, the area of the fractional compensation current pulse must be equal to the area of the charge pump ripple output. Figure 6. Waveforms for NF = 2 Modulo 5 → fraction = 2/5 SR01682 fRF 1930.140 MHz MAIN DIVIDER N = 8042 FRACTIONAL ACCUMULATOR fREF 240 kHz 240.016 kHz ICOMP IPUMP LOOP FILTER & VCO FMOD NF Figure 7. Current Injection Concept |
Similar Part No. - SA7016DH |
|
Similar Description - SA7016DH |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |