Datasheet

AD9559 Data Sheet
Rev. C | Page 100 of 120
DIGITAL LOOP FILTER COEFFICIENTS (REGISTER 0x0800 TO REGISTER 0x0817)
Table 143. Base Digital Loop Filter with Normal Phase Margin (PM = 70°, BW = 0.1 Hz, Third Pole Frequency = 1 Hz, N1 = 1)
1
Address Bits Bit Name Description
0x0800
[7:0]
NPM Alpha-0 linear
Alpha-0 coefficient linear, Bits[7:0]; default: 0x24
0x0801 [7:0] Alpha-0 coefficient linear, Bits[15:8]; default: 0x8C
0x0802 7 Reserved Default: 0b
[6:0] NPM Alpha-1 exponent Alpha-1 coefficient exponent, Bits[6:0]; default: 0x49
0x0803 [7:0] NPM Beta-0 linear Beta-0 coefficient linear, Bits[7:0]; default: 0x55
0x0804 [7:0] Beta-0 coefficient linear, Bits[15:8]; default: 0xC9
0x0805 7 Reserved Default: 0b
[6:0] NPM Beta-1 exponent Beta-1 coefficient exponent, Bits[6:0]; default: 0x7B
0x0806 [7:0] NPM Gamma-0 linear Gamma-0 coefficient linear, Bits[7:0]; default: 0x9C
0x0807 [7:0] Gamma-0 coefficient linear, Bits[15:8]; default: 0xFA
0x0808 7 Reserved Default: 0b
[6:0] NPM Gamma -1 exponent Gamma-1 coefficient exponent, Bits[6:0]; default: 0x55
0x0809 [7:0] NPM Delta-0 linear Delta-0 coefficient linear, Bits[7:0]; default: 0xEA
0x080A [7:0] Delta-0 coefficient linear, Bits[15:8]; default: 0xE2
0x080B 7 Reserved Default: 0b
[6:0] NPM Delta-1 exponent Delta-1 coefficient exponent, Bits[6:0]; default: 0x57
1
Note that the digital loop filter base coefficients (α, β, γ, and δ) have the general form: x(2
y
), where x is the linear component and y is the exponential component of the
coefficient. The value of the linear component (x) constitutes a fraction, where 0 ≤ x ≤ 1. The exponential component (y) is a signed integer. These are live registers;
therefore, an IO_UPDATE is not needed. However, the updated coefficients do not take effect while the loop is locked.
Table 144. Base Digital Loop Filter with High Phase Margin (PM = 88.5°, BW = 0.1 Hz, Third Pole Frequency = 20 Hz, N1 = 1)
1
Address Bits Bit Name Description
0x080C [7:0] HPM Alpha-0 linear Alpha-0 coefficient linear, Bits[7:0]; default = 0x8C
0x080D [7:0] Alpha-0 coefficient linear, Bits[15:8]; default: 0xAD
0x080E 7 Reserved Default: 0b
[6:0] HPM Alpha-1 exponent Alpha-1 coefficient exponent, Bits[6:0]; default: 0x4C
0x080F
[7:0]
HPM Beta-0 linear
Beta-0 coefficient linear, Bits[7:0]; default: 0xF5
0x0810 [7:0] Beta-0 coefficient linear, Bits[15:8]; default: 0xCB
0x0811 7 Reserved Default: 0b
[6:0] HPM Beta-1 exponent Beta-1 coefficient exponent, Bits[6:0]; default: 0x73
0x0812 [7:0] HPM Gamma-0 linear Gamma-0 coefficient linear, Bits[7:0]; default: 0x24
0x0813 [7:0] Gamma-0 coefficient linear, Bits[15:8]; default: 0xD8
0x0814
7
Reserved
Default: 0b
[6:0] HPM Gamma-1 exponent Gamma-1 coefficient exponent, Bits[6:0]; default: 0x59
0x0815 [7:0] HPM Delta-0 linear Delta-0 coefficient linear, Bits[7:0]; default: 0xD2
0x0816
[7:0]
Delta-0 coefficient linear, Bits[15:8]; default: 0x8D
0x0817 7 Reserved Default: 0b
[6:0] HPM Delta-1 exponent Delta-1 coefficient exponent, Bits[6:0]; default: 0x5A
1
Note that the base digital loop filter coefficients (α, β, γ, and δ) have the general form: x(2y), where x is the linear component and y is the exponential component of
the coefficient. The value of the linear component (x) constitutes a fraction, where 0 ≤ x ≤ 1. The exponential component (y) is a signed integer. These are live registers;
therefore, an IO_UPDATE is not needed. However, the updated coefficients do not take effect while the loop is locked.