Digitally controlled spur management technique for integrated DC-DC converters
View Patent ↗An integrated circuit for digital controlling switching noise spurs in a receiver by shifting a switching frequency (f s ) to a clock frequency (f s +Δf) to move a K th harmonic of the switching frequency (f s ) is provided. The integrated circuit includes a spur controlled clock that operates the clock frequency (f s +Δf), and a DC-DC converter circuitry that includes a first power switch, and a second power switch. The first power switch and the second power switch are driven by the clock frequency (f s +Δf). Δf ranges from ( f RF - Kf s ) + BW K to ( f RF - ( K - 1 ) f s ) - BW K - 1 , and f RF is center frequency of a received channel. None of the harmonics of the clock frequency (f s +Δf) is present in a channel of interest. The switching frequency is larger than the channel bandwidth 2BW.
1. An integrated circuit for digital controlling switching noise spurs in a receiver by shifting a switching frequency (f s ) to a clock frequency (f s +Δf) to move a K th harmonic of said switching frequency (f s ), said integrated circuit comprising:
a spur controlled clock that operates said clock frequency (f s +Δf), wherein none of the harmonics of said clock frequency (f s +Δf) is present in a channel of interest, wherein said switching frequency is larger than a bandwidth 2BW of the channel of interest; and
a DC-DC converter circuitry comprising:
a first power switch, and
a second power switch, wherein said first power switch and said second power switch are driven by said clock frequency (f s +Δf),
wherein ·Δf ranges from
(
f
RF
-
Kf
s
)
+
BW
K
to
(
f
RF
-
(
K
-
1
)
f
s
)
-
BW
K
-
1
,
and
wherein f RF is a center frequency of the channel of interest.
2. The integrated circuit of claim 1 , wherein said K th harmonic of said switching frequency is shifted to a higher frequency at Kf s +KΔf, when Δf is a frequency shift.
3. The integrated circuit of claim 1 , wherein said channel of interest at f RF is placed between two consecutive harmonics at (K−1)(f s +Δf) and K(f s +Δf).
4. The integrated circuit of claim 3 , wherein Δf is calculated in accordance with
Δ
f
=
2
f
RF
2
K
-
1
-
f
s
.
5. The integrated circuit of claim 1 , wherein a value of K is chosen to minimize the switching frequency shift Δf for the channel of interest at f RF .
6. A combined integrated circuit for digital controlling switching noise spurs in a receiver by shifting a switching frequency (f s ) to a clock frequency (f s +Δf) to move a K th harmonic of said switching frequency (f s ), said combined integrated circuit comprising:
a spur controlled clock that operates said clock frequency (f s +Δf), wherein none of the harmonics of said clock frequency (f s +Δf) is present in a channel of interest, wherein said switching frequency is larger than a bandwidth 2BW of the channel of interest; and
a DC-DC converter circuitry operatively coupled to analog circuitry, wherein said DC-DC converter comprises:
a first power switch, and
a second power switch, wherein said first power switch and said second power switch are driven by said clock frequency (f s +Δf),
wherein Δf is calculated in accordance with an equation:
Δ
f
=
2
f
RF
2
K
-
1
-
f
s
,
and
wherein f RF is a center frequency of the channel of interest.
7. The combined integrated circuit of claim 6 , wherein said K th harmonic of said switching frequency is shifted by Δf when said switching frequency is greater than the channel bandwidth 2BW.
8. The combined integrated circuit of claim 6 , wherein an absolute value of Δf is determined based on a value of K and f RF .
9. The combined integrated circuit of claim 6 , wherein the value of K is chosen to minimize the switching frequency shift Δf for the channel of interest at f RF .
10. The combined integrated circuit of claim 6 , wherein Δf is a minimum frequency shift of −37.267 KHz when the value of K is 81, f RF is 481 MHz, and f s is 8 MHz.
11. The combined integrated circuit of claim 6 , wherein Δf ranges from
(
f
RF
-
Kf
s
)
+
BW
K
to
(
f
RF
-
(
K
-
1
)
f
s
)
-
BW
K
-
1
.
12. A method for digital controlling switching noise spurs in a DC-DC converter, said method comprising:
calculating a location of a K th harmonic of a switching frequency in said DC-DC converter; and
shifting said K th harmonic of said switching frequency (f s ) to a clock frequency (f s +Δf) based on said location such that none of the harmonics of said clock frequency (f s +Δf) is present in a channel of interest,
wherein Δf ranges from
(
f
RF
-
Kf
s
)
+
BW
K
to
(
f
RF
-
(
K
-
1
)
f
s
)
-
BW
K
-
1
,
and wherein f RF is a center frequency of the channel of interest and BW is a bandwidth of the channel of interest.
13. The method of claim 12 , further comprising shifting said K th harmonic of said switching frequency to a higher frequency at Kf s +KΔf, when Δf is a frequency shift.
14. The method of claim 12 , wherein said channel of interest at f RF is placed between two consecutive harmonics at (K−1)(f s +Δf) and K(f s +Δf).
15. The method of claim 12 , wherein Δf is calculated such that the channel of interest is located between two consecutive harmonics of said switching frequency (f s ).
16. The method of claim 12 , wherein said switching frequency is larger than 2BW.
17. The method of claim 12 , wherein said K th harmonic of said switching frequency (f s ) is shifted by Δf when said switching frequency (f s ) is greater than 2BW.
18. The method of claim 12 , wherein Δf is calculated in accordance with
Δ
f
=
2
f
RF
2
K
-
1
-
f
s
.
19. The method of claim 12 , wherein said shifting said K th harmonic of said switching frequency (f s ) is performed and controlled by a clock phase lock loop (PLL).