BU2373FV_11 Datasheet, PDF (15/19 Pages) Rohm – High Performance VCOs for Image Sampling

BU2373FV,BU2374FV
Technical Note
・By the expression aforementioned, the Gain and the Phase are given as shown in graphs below.
Gain(dB)
20log{R1/(R1+R2)}
<Gain>
-6dB/oct
<Phase>
φ
f_C3
f
π/4
f
f_C3
Fig.66 (Fig.63) Frequency  Gain Characteristics
π/2
Fig.67 (Fig.63) Frequency  Phase Characteristics
1
R1+R2
fC3 = _2π × _{C1・R1・R2}
By combining (1) and (2), finding the Gain and the Phase of the lag-lead filter,
VOUT
1+S・C2・R1
F(s) =
VIN
=
｛1+S・C2・(R1+R2)｝ × ｛1+ S・C1・
R1・R2
R1+R2
｝
The gain and the Phase are given as shown below, respectively.
(S=jω)
Gain=20・log｛
G2
G1×G3
｝
, ^{Phase=θ2-θ1-θ3}
G1= 1+C2²ãƒ»(R1+R2)²ãƒ»(2πf)²
, θ1= -tan^-1｛2_πf・C2・（R1+R2)｝
G2= 1+C2²ãƒ»R1²ãƒ»(2πf)²
, θ2= tan^-1（2πf・C2・R1）
G3=
1+C1²ãƒ»R1²ãƒ»
1
(R1+R2)²
・(2πf)²
,
θ3= -tan^-1｛2πf・C1・
R1・R2
（R1+R2)
｝
Gain(dB)
<Gain>
<Phase>
φ
-6dB/oct
f_C1
f_C2
f_C3
f
π/4
20log{R1/(R1+R2)}
π/2
f
f_C1
f_C2
f_C3
Fig.68 (Fig.61) Frequency  Gain Characteristics
Fig.69 (Fig.61) Frequency  Phase Characteristics
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15/18
2011.08 - Rev.B