Clocking Concept; Audio Concept - Nokia RM-761 Service Manual

RM-761; RM-799; RM-800
System Module

Clocking concept

Figure 53 XG213 clock generation and distribution
The above figure provides an overview of the clock generation and distribution inside XGold213. The 26MHz
DCXO is located in the RF macro and supplies the XGold213 with the main clock input. This clock is optionally
available also on the FSYS1 and FSYS2 outputs as sine wave outputs. In Quantum only FSYS1 is used for the
BTFM module. The 26MHz signal from the DCXO is buffered and made available for the digital part of the
XGold213 through the CGU (Clock Generation Unit). Here a PLL and phase shifters generate higher frequency
clock signals which are then fed to the various on-chip HW blocks through a set of multiplexers and dividers,
allowing for a very flexible clocking scheme. The clocks are also available a digital clock outputs on the CLKOUT
[0:2] balls. Currently in Quantum CLKOUT0 is assigned for the 32 kHz SLEEEPCLK, and CLKOUT2 is assigned for
the camera clock, and CLKOUT1 is not used.
The low power 32 kHz oscillator is enabled under SW control and is available during system sleep for all HW
blocks to allow operation is sleep mode with very low power consumption.

Audio concept

The VMIC supply is intended for the biasing of the internal microphone and the VUMIC for the biasing of the
headset microphone. There are 4 voltage settings for VMIC and VUMIC ranging between 1.8V and 2.2V. The
default setting for both supplies in XMM2130 reference design is 2.2V. VUMIC has an ultra-low-power mode
which is used only when a headset is connected and the mobile station is in sleep mode. To be able to detect
a key press on the hook key, the bias supply needs to be enabled. VUMIC is switched to the standard mode
during audio operation for optimal noise performance.
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