SAMSUNG Proprietary-Contents may change without notice
11-4
STH-N271
Circuit Description
1-3. IF INTERFACE CHIP (IFC :U101)
The IFC provides the radio IF and audio interfaces (Figure2-2). Differential Rx I/Q and Tx I/Q signal pairs
interface directly with the RF interface chip (RFIC : U304) device. MOD, AFC, AGC, RSSI, and PA_CNT signals
also directly control the radio circuitry. Three audio paths are implemented. The primary path utilizes the
microphone and speaker, located on board. Both microphone and speaker utilize the main differential circuits
in the IFC to minimize noise pickup. The speaker output is amplified internally to enable direct connection to
the speaker. The second audio path connects to the headset jack. The headset microphone and speaker are
passed to the IFC’s auxiliary input and output, respectively. The headset jack terminals indicate via the
HEADSET_SENSE line when the headset is present as well as when the headset button is pushed via the
SEND_END line. The third audio path to the HFK shares the auxiliary output with the headset for its speaker
and uses the second auxiliary input for its microphone. Since the auxiliary output is not internally amplified,
an external audio amplifier is applied before connection to the two headset and HFK.
Figure 2-2.IFC interface and block diagram