CXD3018Q/R
§5-9. MIRR and DFCT Signal Generation
The RF signal obtained from the RFDC pin is sampled at approximately 1.4MHz (when MCK = 128Fs) and
loaded. The MIRR and DFCT signals are generated from this RF signal.
MIRR Signal Generation
The loaded RF signal is applied to peak hold and bottom hold circuits.
An envelope is generated from the waveforms generated in these circuits, and the MIRR comparator level is
generated from the average of this envelope waveform.
The MIRR signal is generated by comparing the waveform generated by subtracting the bottom hold value
from the peak hold value with this MIRR comparator level. (See Fig. 5-11.)
The bottom hold speed and mirror sensitivity can be selected from four values using D7 and D6, and D5 and
D4, respectively, of $3C.
RF
Peak Hold
Bottom Hold
Peak Hold
MIRR Comp
– Bottom Hold
(Mirror comparator level)
H
L
MIRR
Fig. 5-11
DFCT Signal Generation
The loaded RF signal is input to two peak hold circuits with different time constants, and the DFCT signal is
generated by comparing the difference between these two peak hold waveforms with the DFCT comparator
level. (See Fig. 5-12.)
The DFCT comparator level can be selected from four values using D13 and D12 of $3B.
RF
Peak Hold1
Peak Hold2
Peak Hold
SDF
– Bottom Hold
(Defect comparator level)
H
L
DFCT
Fig. 5-12
– 95 –
ETC [ ETC ]
